• 한국IT서비스학회지
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• 제7권2호
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• pp.59-75
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• 2008

Despite our extensive understanding on the Internet business and widely understood first-mover advantage. it is not clearly answered yet whether an internet firm can enjoy the first-mover advantage in the new environment of the Internet. This is mainly because the Internet marketplace itself has a complex combination of various business models, ranging from a simple channel-extension to a whole new business model. Based on new theoretical development on the first-mover advantage, we empirically test whether being an early mover in the Internet environment materially affects firm performance, using clickstream data from Korea where broadband Internet installation is ranked as top among OECD countries. Our results show the effectiveness of first-mover advantage on the web does not exist, regardless of its business model and competitive environment. This result expands our understandings on the e-business, not to mention of the real feature of first-mover advantage.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.285-288
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• 2001

In the speech analysis, to estimate formant center frequencies exactly is very important. If we know formant frequencies, we can expect which pronunciation is uttered. Generally, the magnitude of first formant frequency in voiced speech is 10dB more than other formant frequency. So, the shape of voice signal in time domain is affected by mainly first formant. Therefore we can get first formant frequency roughly by using ZCR(Zero Cross Rate). In this paper, we proposed the improvement method to get first formant frequency by using ZCR. We did autocorrelation before getting ZCR. This procedure makes voice signal smooth so, first formant in voice signal is emphasized. As a result of this method, we got more exact ZCR and first formant frequency. Conventional method of formant estimate is done in frequency domain but proposed method is done in time domain. So, this is very simple.

• 산업경영시스템학회지
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• 제38권1호
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• pp.74-82
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• 2015

Two key challenges in statistical relational learning are uncertainty and complexity. Standard frameworks for handling uncertainty are probability and first-order logic respectively. A Markov logic network (MLN) is a first-order knowledge base with weights attached to each formula and is suitable for classification of dataset which have variables correlated with each other. But we need domain knowledge to construct first-order logics and a computational complexity problem arises when calculating weights of first-order logics. To overcome these problems we suggest a method to generate first-order logics and learn weights using association analysis in this study.

• International Journal of Advanced Culture Technology
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• 제8권2호
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• pp.277-282
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• 2020

The first zoea of Microcassiope orientalis is described and illustrated from laboratory hatched materials. Comparisons with previous studies of the first zoeal stages in the Xanthidae from Korean waters, revealed that some former studies were incorrected. The first zoea of M. orientalis described by Ko was identical to the first zoea of Macromedaeus distinguendus described by Terada. In addition, zoeal stages of Nanocassiope granullipes described by Ko & Clark was revealed the zoeal stages of M. cassiopes. So, the first zoea of M. orientalis is redescribed and illustrated in detailed with color photo herein, and compare its morphological characteristics with previous described zoea of N. granulipes by Ko & Clark.

• BMB Reports
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• 제54권5호
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• pp.284-284
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• 2021

• Clinical and Experimental Pediatrics
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• 제49권5호
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• pp.482-488
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• 2006

목 적 : 신생아의 첫 태변 및 초뇨 배출 시간은 건강 상태의 양호한 정도를 나타내는 표지이다. 첫 태변 배출 시간과 초뇨 배출 시간에 영향을 미칠 수 있는 여러 인자들에 대해 조사하고 이를 비교 평가 분석함으로써 그 임상적 의의를 비교 관찰하였다. 방 법 : 2004년 11월부터 2005년 4월까지 본원에서 분만된 재태 연령 34주 이상의 신생아 1,221명을 대상으로 하였다. 모체의 인구학적 변수(모체 연령, 분만력, 분만 방법, 양수의 태변 착색 여부, 그리고 모체 당뇨 여부)와 영아의 변수(성별, Apgar 점수, 재태 연령, 출생 체중, 첫 24시간 동안의 수유 유형, 첫 수유 시 연령, 출생 후 12시간까지 수유 횟수, 퇴원 시 연령, 첫 번째 배뇨 시 연령, 첫 번째 태변 배출 시 연령)에 따른 태변 배출 및 초뇨 배출 시간을 비교 분석하였다. 결 과 : 본 연구에서, 58.8%가 12시간 이전에, 95.3%가 24시간 이전에, 99.8%가 36시간 이전에 초뇨가 배출되었다. 그리고 68.3%가 12시간 이전에, 95.8%가 24시간 이전에, 98.3%가 36시간 이전에 태변이 배출되었다. 미숙아와 만삭아를 비교하였을 때 초뇨 배출시 연령은 각각 $6.5{\pm}5.8$시간, $12.1{\pm}6.6$시간이었고(P=0.000), 첫 태변 배출시 연령은 각각 $20.7{\pm}13.5$시간, $10.0{\pm}6.3$시간(P=0.000)으로 미숙아의 경우에 초뇨가 더 빨리 배출되고 태변이 더 늦게 배출되는 경향을 나타냈다. 수유를 빨리 시작한 경우에 초뇨나 첫 태변 배출 시간이 통계학적으로 유의하게 더 빨랐다. 출생 후 첫 12시간 동안의 수유 횟수는 초뇨 배출 시간과는 큰 상관이 없었다(P=0.778). 수유 횟수가 많을수록 24시간 이내에 첫 태변을 배출한 영아가 더 많았으며 이는 통계학적으로 유의하였다(P=0.000). 분만 방법(질식 분만, 수술 분만), Apgar 점수, 출산력, 성별, 수유 유형, 모체 당뇨 여부 등은 초뇨 배출 및 첫 태변 배출시 연령과는 통계학적으로 유의성은 없었다. 결 론 : 재태 연령, 출생 체중, 초기 수유 시작 시간이 초뇨 및 첫 태변 배출 시간과 연관성이 있는 것으로 보여지며, 초뇨 및 태변 배출의 지연을 보일 경우 동반되는 이상 증상의 유무에 대한 면밀한 관찰 외에도 상기 요소들에 대한 사항을 고려하여 성급하고 불필요한 임상 검사 및 치료는 피해야 할 것으로 사료된다.

• 대한수학회보
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• 제41권4호
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• pp.665-676
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• 2004

In this paper we characterize asymptotic stability via Lyapunov function in general dynamical systems on c-first countable space. We give a family of examples which have first countable but not c-first countable, also c-first countable and locally compact space but not metric space. We obtain several necessary and sufficient conditions for a compact subset M of the phase space X to be asymptotic stability.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제12권2호
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• pp.109-118
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• 2008

We present a new version of the first return time test for pseudorandomness. Let $R_n$ be the first return time of initial n-block with overlapping. An algorithm to calculate the probability distribution of the first return time $R_n$ for each starting block is presented and used to test pseudorandom number generators. The standard Z-test for log $R_n$ is applied to test the pseudorandom number generators.

• Kyungpook Mathematical Journal
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• 제58권2호
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• pp.221-229
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• 2018

The first Zagreb eccentricity index $E_1(G)$ of a graph G is defined as the sum of squares of the eccentricities of the vertices. In this paper some bounds for the first Zagreb eccentricity index and first Zagreb degree eccentricity index are computed.

• 천문학회보
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• 제37권2호
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• pp.76.2-76.2
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• 2012

We present the first simulations of cosmic reionization that include the first stars and their radiative feedback that limited their formation, in a volume large enough to capture the spatial variations that affected the process and its observability. We show hat these first stars made reionization begin much earlier than without, and was reatly extended, which boosts the intergalactic electron-scattering optical depth and the large-angle polarization fluctuations of the cosmic microwave background (CMB) significantly. Although within current WMAP uncertainties, this will enable Planck see he signature of the first stars at high redshift, currently undetectable by other probes.