거의 한달에 한번씩 Silicon Valley에 오는거 같다. 오늘은 Oceans International의 고객사인 Clunix 사가 실리콘 밸리에서 BlueRun Ventures라는 venture capital회사와 미팅이 있어서 왔다. Supercomputing 관련 솔루션을 제공하는 8년된 베테랑 벤처 기업인 Clunix의 권대석 사장님과 김소헌 실장님이 Lake Tahoe에서 열린 SC2007 행사를 성공적으로 마친 후 한국 들어가기전에 잠시 들리셨다.
나는 실리콘 밸리를 사랑한다. 내가 99년 미국에 와서 처음으로 정착한 곳이 이 동네라서 그런지 모르겠지만, 하여튼 이 동네에 오면 마음이 편해진다. “필라델피아에서도 몇 개월 있다보면 정이 들겠지” 라는 생각을 하지만, 실리콘 밸리와 같은 느낌은 나지 않을거 같다..자, 그러면 실리콘 밸리가 뭐가 그렇게 특별날까? 많은 지역과 나라들이 실리콘 밸리의 dynamics (자본, 기술, 우수한 인력 등..)에 대해서 연구한 후에 각자의 지역에 replicate하려는 노력들을 많이 하였지만 아직까지 실리콘 밸리를 100% 복사하는데는 실패하였다. 뉴욕의 Silicon Alley, Texas의 Silicorn Valley, 한국의 대덕 연구 단지/테헤란 밸리…흉내는 내지만, 뭔가 많이 부족하다…What is it so special about Silicon Valley and how do we become one?
Y Combinator의 창업자인 Paul Graham의 블로그에서 이 질문에 대한 답을 찾았다. 바로 How to be Silicon Valley라는 글인데, 모두들 자세히 읽어보시라고 권장하고 싶다. 이 글을 읽으면 실리콘 밸리가 왜 실리콘 밸리이며, 전세계 IT 창업자들과 엔지니어들이 뼈를 묻고 싶어하는 곳인지 5% 정도는 이해할 수 있을것이다. 나도 꼭 졸업 후 이 동네에서 살고 싶다…Man, I love this place!
Could you reproduce Silicon Valley elsewhere, or is there something unique about it?It wouldn’t be surprising if it were hard to reproduce in other countries, because you couldn’t reproduce it in most of the US either. What does it take to make a silicon valley even here?What it takes is the right people. If you could get the right ten thousand people to move from Silicon Valley to Buffalo, Buffalo would become Silicon Valley. That’s a striking departure from the past. Up till a couple decades ago, geography was destiny for cities. All great cities were located on waterways, because cities made money by trade, and water was the only economical way to ship.Now you could make a great city anywhere, if you could get the right people to move there. So the question of how to make a silicon valley becomes: who are the right people, and how do you get them to move?
Two Types
I think you only need two kinds of people to create a technology hub: rich people and nerds. They’re the limiting reagents in the reaction that produces startups, because they’re the only ones present when startups get started. Everyone else will move.Observation bears this out: within the US, towns have become startup hubs if and only if they have both rich people and nerds. Few startups happen in Miami, for example, because although it’s full of rich people, it has few nerds. It’s not the kind of place nerds like.Whereas Pittsburgh has the opposite problem: plenty of nerds, but no rich people. The top US Computer Science departments are said to be MIT, Stanford, Berkeley, and Carnegie-Mellon. MIT yielded Route 128. Stanford and Berkeley yielded Silicon Valley. But Carnegie-Mellon? The record skips at that point. Lower down the list, the University of Washington yielded a high-tech community in Seattle, and the University of Texas at Austin yielded one in Austin. But what happened in Pittsburgh? And in Ithaca, home of Cornell, which is also high on the list?I grew up in Pittsburgh and went to college at Cornell, so I can answer for both. The weather is terrible, particularly in winter, and there’s no interesting old city to make up for it, as there is in Boston. Rich people don’t want to live in Pittsburgh or Ithaca. So while there are plenty of hackers who could start startups, there’s no one to invest in them.
Not Bureaucrats
Do you really need the rich people? Wouldn’t it work to have the government invest in the nerds? No, it would not. Startup investors are a distinct type of rich people. They tend to have a lot of experience themselves in the technology business. This (a) helps them pick the right startups, and (b) means they can supply advice and connections as well as money. And the fact that they have a personal stake in the outcome makes them really pay attention.Bureaucrats by their nature are the exact opposite sort of people from startup investors. The idea of them making startup investments is comic. It would be like mathematicians running Vogue– or perhaps more accurately, Vogue editors running a math journal. Though indeed, most things bureaucrats do, they do badly. We just don’t notice usually, because they only have to compete against other bureaucrats. But as startup investors they’d have to compete against pros with a great deal more experience and motivation.Even corporations that have in-house VC groups generally forbid them to make their own investment decisions. Most are only allowed to invest in deals where some reputable private VC firm is willing to act as lead investor.
Not Buildings
If you go to see Silicon Valley, what you’ll see are buildings. But it’s the people that make it Silicon Valley, not the buildings. I read occasionally about attempts to set up “technology parks” in other places, as if the active ingredient of Silicon Valley were the office space. An article about Sophia Antipolis bragged that companies there included Cisco, Compaq, IBM, NCR, and Nortel. Don’t the French realize these aren’t startups?Building office buildings for technology companies won’t get you a silicon valley, because the key stage in the life of a startup happens before they want that kind of space. The key stage is when they’re three guys operating out of an apartment. Wherever the startup is when it gets funded, it will stay. The defining quality of Silicon Valley is not that Intel or Apple or Google have offices there, but that they were started there.So if you want to reproduce Silicon Valley, what you need to reproduce is those two or three founders sitting around a kitchen table deciding to start a company. And to reproduce that you need those people.
Universities
The exciting thing is, all you need are the people. If you could attract a critical mass of nerds and investors to live somewhere, you could reproduce Silicon Valley. And both groups are highly mobile. They’ll go where life is good. So what makes a place good to them?What nerds like is other nerds. Smart people will go wherever other smart people are. And in particular, to great universities. In theory there could be other ways to attract them, but so far universities seem to be indispensable. Within the US, there are no technology hubs without first-rate universities– or at least, first-rate computer science departments.So if you want to make a silicon valley, you not only need a university, but one of the top handful in the world. It has to be good enough to act as a magnet, drawing the best people from thousands of miles away. And that means it has to stand up to existing magnets like MIT and Stanford.This sounds hard. Actually it might be easy. My professor friends, when they’re deciding where they’d like to work, consider one thing above all: the quality of the other faculty. What attracts professors is good colleagues. So if you managed to recruit, en masse, a significant number of the best young researchers, you could create a first-rate university from nothing overnight. And you could do that for surprisingly little. If you paid 200 people hiring bonuses of $3 million apiece, you could put together a faculty that would bear comparison with any in the world. And from that point the chain reaction would be self-sustaining. So whatever it costs to establish a mediocre university, for an additional half billion or so you could have a great one.
Personality
However, merely creating a new university would not be enough to start a silicon valley. The university is just the seed. It has to be planted in the right soil, or it won’t germinate. Plant it in the wrong place, and you just create Carnegie-Mellon.To spawn startups, your university has to be in a town that has attractions other than the university. It has to be a place where investors want to live, and students want to stay after they graduate.The two like much the same things, because most startup investors are nerds themselves. So what do nerds look for in a town? Their tastes aren’t completely different from other people’s, because a lot of the towns they like most in the US are also big tourist destinations: San Francisco, Boston, Seattle. But their tastes can’t be quite mainstream either, because they dislike other big tourist destinations, like New York, Los Angeles, and Las Vegas.There has been a lot written lately about the “creative class.” The thesis seems to be that as wealth derives increasingly from ideas, cities will prosper only if they attract those who have them. That is certainly true; in fact it was the basis of Amsterdam’s prosperity 400 years ago.A lot of nerd tastes they share with the creative class in general. For example, they like well-preserved old neighborhoods instead of cookie-cutter suburbs, and locally-owned shops and restaurants instead of national chains. Like the rest of the creative class, they want to live somewhere with personality.What exactly is personality? I think it’s the feeling that each building is the work of a distinct group of people. A town with personality is one that doesn’t feel mass-produced. So if you want to make a startup hub– or any town to attract the “creative class”– you probably have to ban large development projects. When a large tract has been developed by a single organization, you can always tell. Most towns with personality are old, but they don’t have to be. Old towns have two advantages: they’re denser, because they were laid out before cars, and they’re more varied, because they were built one building at a time. You could have both now. Just have building codes that ensure density, and ban large scale developments.A corollary is that you have to keep out the biggest developer of all: the government. A government that asks “How can we build a silicon valley?” has probably ensured failure by the way they framed the question. You don’t build a silicon valley; you let one grow.
Nerds
If you want to attract nerds, you need more than a town with personality. You need a town with the right personality. Nerds are a distinct subset of the creative class, with different tastes from the rest. You can see this most clearly in New York, which attracts a lot of creative people, but few nerds. What nerds like is the kind of town where people walk around smiling. This excludes LA, where no one walks at all, and also New York, where people walk, but not smiling. When I was in grad school in Boston, a friend came to visit from New York. On the subway back from the airport she asked “Why is everyone smiling?” I looked and they weren’t smiling. They just looked like they were compared to the facial expressions she was used to.If you’ve lived in New York, you know where these facial expressions come from. It’s the kind of place where your mind may be excited, but your body knows it’s having a bad time. People don’t so much enjoy living there as endure it for the sake of the excitement. And if you like certain kinds of excitement, New York is incomparable. It’s a hub of glamour, a magnet for all the shorter half-life isotopes of style and fame.Nerds don’t care about glamour, so to them the appeal of New York is a mystery. People who like New York will pay a fortune for a small, dark, noisy apartment in order to live in a town where the cool people are really cool. A nerd looks at that deal and sees only: pay a fortune for a small, dark, noisy apartment.Nerds will pay a premium to live in a town where the smart people are really smart, but you don’t have to pay as much for that. It’s supply and demand: glamour is popular, so you have to pay a lot for it.Most nerds like quieter pleasures. They like cafes instead of clubs; used bookshops instead of fashionable clothing shops; hiking instead of dancing; sunlight instead of tall buildings. A nerd’s idea of paradise is Berkeley or Boulder.
Youth
It’s the young nerds who start startups, so it’s those specifically the city has to appeal to. The startup hubs in the US are all young-feeling towns. This doesn’t mean they have to be new. Cambridge has the oldest town plan in America, but it feels young because it’s full of students.What you can’t have, if you want to create a silicon valley, is a large, existing population of stodgy people. It would be a waste of time to try to reverse the fortunes of a declining industrial town like Detroit or Philadelphia by trying to encourage startups. Those places have too much momentum in the wrong direction. You’re better off starting with a blank slate in the form of a small town. Or better still, if there’s a town young people already flock to, that one.The Bay Area was a magnet for the young and optimistic for decades before it was associated with technology. It was a place people went in search of something new. And so it became synonymous with California nuttiness. There’s still a lot of that there. If you wanted to start a new fad– a new way to focus one’s “energy,” for example, or a new category of things not to eat– the Bay Area would be the place to do it. But a place that tolerates oddness in the search for the new is exactly what you want in a startup hub, because economically that’s what startups are. Most good startup ideas seem a little crazy; if they were obviously good ideas, someone would have done them already.(How many people are going to want computers in their houses? What, another search engine?)That’s the connection between technology and liberalism. Without exception the high-tech cities in the US are also the most liberal. But it’s not because liberals are smarter that this is so. It’s because liberal cities tolerate odd ideas, and smart people by definition have odd ideas.Conversely, a town that gets praised for being “solid” or representing “traditional values” may be a fine place to live, but it’s never going to succeed as a startup hub. The 2004 presidential election, though a disaster in other respects, conveniently supplied us with a county-by-county map of such places. To attract the young, a town must have an intact center. In most American cities the center has been abandoned, and the growth, if any, is in the suburbs. Most American cities have been turned inside out. But none of the startup hubs has: not San Francisco, or Boston, or Seattle. They all have intact centers. My guess is that no city with a dead center could be turned into a startup hub. Young people don’t want to live in the suburbs.Within the US, the two cities I think could most easily be turned into new silicon valleys are Boulder and Portland. Both have the kind of effervescent feel that attracts the young. They’re each only a great university short of becoming a silicon valley, if they wanted to.
Time
A great university near an attractive town. Is that all it takes? That was all it took to make the original Silicon Valley. Silicon Valley traces its origins to William Shockley, one of the inventors of the transistor. He did the research that won him the Nobel Prize at Bell Labs, but when he started his own company in 1956 he moved to Palo Alto to do it. At the time that was an odd thing to do. Why did he? Because he had grown up there and remembered how nice it was. Now Palo Alto is suburbia, but then it was a charming college town– a charming college town with perfect weather and San Francisco only an hour away.The companies that rule Silicon Valley now are all descended in various ways from Shockley Semiconductor. Shockley was a difficult man, and in 1957 his top people– “the traitorous eight”– left to start a new company, Fairchild Semiconductor. Among them were Gordon Moore and Robert Noyce, who went on to found Intel, and Eugene Kleiner, who founded the VC firm Kleiner Perkins. Forty-two years later, Kleiner Perkins funded Google, and the partner responsible for the deal was John Doerr, who came to Silicon Valley in 1974 to work for Intel.So although a lot of the newest companies in Silicon Valley don’t make anything out of silicon, there always seem to be multiple links back to Shockley. There’s a lesson here: startups beget startups. People who work for startups start their own. People who get rich from startups fund new ones. I suspect this kind of organic growth is the only way to produce a startup hub, because it’s the only way to grow the expertise you need.That has two important implications. The first is that you need time to grow a silicon valley. The university you could create in a couple years, but the startup community around it has to grow organically. The cycle time is limited by the time it takes a company to succeed, which probably averages about five years.The other implication of the organic growth hypothesis is that you can’t be somewhat of a startup hub. You either have a self-sustaining chain reaction, or not. Observation confirms this too: cities either have a startup scene, or they don’t. There is no middle ground. Chicago has the third largest metropolitan area in America. As source of startups it’s negligible compared to Seattle, number 15.The good news is that the initial seed can be quite small. Shockley Semiconductor, though itself not very successful, was big enough. It brought a critical mass of experts in an important new technology together in a place they liked enough to stay.
Competing
Of course, a would-be silicon valley faces an obstacle the original one didn’t: it has to compete with Silicon Valley. Can that be done? Probably.One of Silicon Valley’s biggest advantages is its venture capital firms. This was not a factor in Shockley’s day, because VC funds didn’t exist. In fact, Shockley Semiconductor and Fairchild Semiconductor were not startups at all in our sense. They were subsidiaries– of Beckman Instruments and Fairchild Camera and Instrument respectively. Those companies were apparently willing to establish subsidiaries wherever the experts wanted to live.Venture investors, however, prefer to fund startups within an hour’s drive. For one, they’re more likely to notice startups nearby. But when they do notice startups in other towns they prefer them to move. They don’t want to have to travel to attend board meetings, and in any case the odds of succeeding are higher in a startup hub.The centralizing effect of venture firms is a double one: they cause startups to form around them, and those draw in more startups through acquisitions. And although the first may be weakening because it’s now so cheap to start some startups, the second seems as strong as ever. Three of the most admired “Web 2.0” companies were started outside the usual startup hubs, but two of them have already been reeled in through acquisitions.Such centralizing forces make it harder for new silicon valleys to get started. But by no means impossible. Ultimately power rests with the founders. A startup with the best people will beat one with funding from famous VCs, and a startup that was sufficiently successful would never have to move. So a town that could exert enough pull over the right people could resist and perhaps even surpass Silicon Valley.For all its power, Silicon Valley has a great weakness: the paradise Shockley found in 1956 is now one giant parking lot. San Francisco and Berkeley are great, but they’re forty miles away. Silicon Valley proper is soul-crushing suburban sprawl. It has fabulous weather, which makes it significantly better than the soul-crushing sprawl of most other American cities. But a competitor that managed to avoid sprawl would have real leverage. All a city needs is to be the kind of place the next traitorous eight look at and say “I want to stay here,” and that would be enough to get the chain reaction started.
vc
MGMT804 – Venture Capital and Entrepreneurial Management
나의 favorite 과목이다. 일주일에 한번, 3시간 동안 진행하는 수업인데, 와튼 교수가 아니라 현재 필라델피아에 위치한 Novitas Venture Capital에서 활동하는 두 파트너 Scott Nissenbaum과 Dean Miller가 번갈아 가면서 강의를 한다. 항상 느끼는 점이지만, 교수보다는 현업에 종사하고 계시는 분들이 역시 가장 최신의 industry knowledge를 가지고 있는거 같다. 이 수업을 듣는 학생들은 두부류가 있는거 같다. 나와 같이 졸업 후 venture capitalist가 되고 싶어하는 학생들과, 졸업 후 창업을 생각하고 있는 entrepreneur 들이다. Entrepreneur들도 VC들의 성향과 사고방식을 이해하고 있어야지만, 향 후 투자를 받을 때 더 좋은 조건에 돈을 받을 수 있다는 생각에 많은 예비 창업가 들이 이 수업을 듣는다. 수업 진행 방식은 다른 수업과 크게 다르지 않다. 일단 수업 참여도가 매우 중요하다. 원형 강의실 앞에 조교가 앉아서 어떤 학생들이 손을 들고, 어떤 질문이나 어떤 comment를 하며, 그 comment가 수업 내용과 적절한지를 즉시 평가 한다. 이 점수들이 학기말에 모여서 성적에 매우 큰 영향을 미치는 관계로, 너도 나도 한마디라도 더 하려고 아예 3시간 내내 손을 들고 있는 학생들도 있다 (나도 그런적이 있는데 발표를 너무 많이 하면 잘 안시키는 문제점도 있다. 교수가 일부러 시선을 피하고 다른 곳을 보고 그러더라) 사업계획서를 보는 방법, 매출이 전혀 없는 인터넷 기업을 평가 (valuation)하는 다양한 방법, term sheet 작성, 벤처 기업 평가와 관련된 legal issue 등과 같이 실제로 일을 할 때 바로 써먹을 수 있는 살아있는 지식을 가르치는 이 수업을 나는 상당히 좋아한다. 어느정도 이론이 바탕이 되지만, 현업에 종사하고 있는 이 두 명의 노련한 VC들의 입에서 나오는 말 하나하나가 주옥 같은 지식이기 때문에 MGMT804 수업 시간에는 맨 앞 줄에 앉아서 집중을 많이 하는 편이다. Venture Capitalist나 창업을 고려하고 있다면 반드시 들어보라고 추천하는 수업 중 하나이다.
이 수업도 reading 만만치 않다. 매 수업 시간마다 약 50장의 reading을 해야하는데 왠만하면 다 읽어 보려고 항상 노력은 한다 (그런데 결국은 다 못 읽는다 ㅎㅎㅎ). 그리고 수업 시작하기 전에 매 시간마다 제출 해야하는 숙제가 있는데 주어진 미니 케이스 (caselette)를 읽고 5-6개의 문제에 대해서 간단하게 2장의 보고서를 작성하는 것이다. 혼자서는 못하고 팀을 만들어서 같이 일을 해야 한다. 불행하게도 이 수업을 듣는 1학년이 거의 없다. 대부분 다른 core 과목 (나는 몇 개는 waive를 했다)과 수업 시간이 겹치기 때문에 2학년 학생들이 주류를 이루고 있어서 내가 아는 사람이 별로 없다. 첫 수업 시간에 내 옆에 앉은 중국 여자 Ming Fu와 같은 팀을 만들었는데 Ming은 와튼 학생이 아니라 프랑스의 INSEAD에서 온 교환 학생이다. 와튼의 장점 중 하나가 유럽과 아시아의 다양한 business school과 partnership을 맺어서 원한다면 일년에 3-4개월 정도는 다른 대륙에 있는 학교에서 공부를 할 수 있는 좋은 프로그램들이 많다는 점이다. 물론 학점 interchange가 된다.
MGMT801 – Entrepreneurship
이 수업 또한 매우 재미있는 수업이다. “Entrepreneurship (창업가 정신) 이란 과연 무엇인가?” 첫 수업시간에 Gary Dushnitsky 교수가 학생들한테 던진 질문이다. 우리는 앞으로 한 학기 동안 이 질문에 대한 답을 찾기 위하여 다양한 case를 분석하고, 색다른 경험을 가지고 있는 classmate들과의 토론을 통하여 많은 고민을 하고, 많은 연구를 하고 그리고 이러한 이론을 바탕으로 실제 벤처기업이 직면한 문제점을 분석한 후, 구체적인 해결책을 제시할 수 있는 프로젝트를 진행할 계획이다. 이 수업 또한 3-4명의 프로젝트 팀을 구성하여야 한다. 우리 learning team의 Brian Gornick, 클래식 피아니스트이자 전 investment banker였던 명석한 두뇌의 소유자 Kevin Lenaghan 그리고 구 소련과 카자흐스탄에서 정부로비스트 일을 하던 tough guy David Larson이 우리 팀이다. 4명 다 전통적인 career path를 밟는거 보다는 창업에 관심이 많은 멤더들이라서 이 그룹이 훨씬 더 dynamic하고 재미있는거 같다. 그리고 프로젝트로는 TechCrunch40 행사를 빛냈던 뮤직쉐이크의 미국 진출 전략에 대한 조금 더 구체적인 해답을 제공하기로 하였다.
MGMT801 수업은 다음과 같이 진행된다. 일주일에 두 번, 한 시간 반씩 수업을 하며 매 수업마다 주어진 reading이 있다. 대부분의 reading은 Harvard Business School에서 작성한 case이며, 독자는 각 case에 대해서 구체적인 결론을 내려야 한다. 가령, “HP가 ink cartridge refill 사업에 진출해야하는가?” “Nantucket Nectar는 상장을 해야하는가 아니면 인수합병을 하여야 하는가?”라는 질문에 대해서 Yes or No 입장을 결정한 후, 왜 이런 결론을 내렸는가에 대하여 구체적인 data와 사례를 통해서 본인의 입장을 backup 할 수 있어야 한다. 나는 개인적으로 이런 발표/토론식 수업을 참 좋아한다. 내가 발표하는걸 좋아해서이기도 하지만, 동료들의 thinking process와 개개인의 다른 background가 와튼의 diversity에 기여하는 현장을 목격하면 참으로 대단하다는 생각을 한다. Collective wisdom이라고나 할까…작은 강의실에서 high performance brain power들이 생성하는 에너지는 정말 대단하다
More on TechCrunch20
몇 일전에 MusicShake와 TechCrunch20이라는 행사에 대해서 내가 잠깐 설명을 하였다. 최종 100위안에는 들었고, TechCrunch20 본부의 소식을 기다리고 있었는데 드디어 최종 40위 안에 들었다는 통보를 받았다. 정말 너무 감격적인 순간이었다…회계 수업 중에 Blackberry를 통해서 이메일 확인을 하였는데 우리가 40위 안에 들었으니 데모 준비를 다시 하라는 내용이었다. 그것도 이번에는 TechCrunch의 창업자인 Michael Arrington을 대상으로 하는 데모이다…Michael 역시 실리콘 밸리에서는 전설적인 존재이자 father figure이다. Michael이 좋은 회사라는 review를 TechCrunch blog에 올리면 그 회사는 잘될 확률이 60% 정도의 승산이 생길만큼 이 동네에서는 입지적인 존재이다.
몇일전에 하였던 데모를 조금 더 손을 본 후 동부 시간 8시부터 약 30분 가량 Webex 및 conference call을 통해서 Musicshake의 장점을 열심히 pitch 하였다. 내가 생각해도 매우 성공적인 presentation이었던거 같은데 아니다 다를까 Michael은 Musicshake의 제품 및 서비스에 매우 감명을 받은거 같았다. “Kihong, 나는 최종 20개 기업 중 하나로 Musicshake를 추천하고 싶다. 이건 정말 재미있는 서비스인거 같다..TechCrunch20은 바로 이런 혁신적인 기업이 데뷔를 하는 행사이다. 하지만, 다른 팀원들과 의견일치를 봐야하니 다음 주 월요일에 정확한 결과를 알려주겠다.”
전화를 끊자마자 가슴이 쿵쾅쿵쾅 뛰는걸 느낄 수 있었다. 꿈만같은 현실이 눈앞에 다가온것이다…9월17일/18일 샌프란시스코에서 세계 최고의 technologist들/venture capitalist 그리고 언론사를 대상으로 내가 직접 미래를 바꿀 수 있는 기업에 대한 소개를 하게되다니…물론 최종 20위에 들면 그렇다는 거지만 내 느낌으로는 거의 된거 같다…
바로 지현이한테 이 기쁜 소식을 알렸고 Oceans International 파트너 John한테 연락을 했다. 그리고 물론 한국에서 이 소식을 기다리고 있는 Musicshake에도 기쁜 소식을 알렸다…
이제 8월20일까지는 fingers crossed하고 기다리는 수 밖에 없다…