• 한국방재안전학회논문집
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• 제6권2호
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• pp.1-8
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• 2013

우리나라 전체 재해 60%이상인 태풍과 같은 바람재난으로부터 구조물이나 외장재가 안전과 사용성 측면에서 설계되려면 내풍설계과정에서 기본풍속, 설계속도압, 풍하중 등 많은 파라미터들이 요구된다. 본 논문에서는 최근 2003년부터 2012년까지의 10년 동안 년최대풍속이 발생한 날의 풍속으로부터 확률과정과 확률분포, 통계적 성질 등을 알아보기 위하여 8개의 대표지점을 여수, 인천, 서울, 청주, 원주, 대구, 속초, 울릉도로 선정했다. 선정된 각 지점에 대한 최근 10년 동안의 풍속자료는 기상청으로부터 획득했다. 각 지점의 획득한 풍속자료는 우리나라를 직접 통과하면서 영향을 미친 태풍과 통과는 안했지만 간접 영향을 미친 태풍, 년최대순간풍속과 년최대평균퐁속이 같은 날 등을 고려 90개의 앙상블 중 선별된 33개의 모집단에 대한 풍속자료의 확률과정 및 확률분포의 특성을 비교 검토하였다.

• 천문학회보
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• 제41권2호
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• pp.30.2-30.2
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• 2016

M104 (NGC 4594, the Sombrero) is an intriguing disk galaxy classified as an elliptical galaxy nowadays. It hosts a luminous bulge and a massive disk, but it is still mysterious how M104 acquired such peculiar structures. Globular clusters are an useful tracer to investigate the formation history of early-type galaxies. In this study we present a wide field imaging study of the globular clusters in M104. Using wide ($1^{\circ}{\times}1^{\circ}$) and deep ugi images of M104 obtained with the CFHT/MegaCam observations, we detect a large number of globular clusters. The color distribution of these globular clusters shows that there are two subpopulations: a metal-poor system and a metal-rich system. The radial number density of the metal-poor globular clusters shows a long tail reaching R ~ 30' (~ 80 kpc), indicating clearly the existence of a giant metal-poor halo in M104. This result is consistent with the previous studies on the dual halos of massive early-type galaxies. We will discuss implications of these results in relation with the formation history of M104.

• 한국안전학회지
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• 제30권6호
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• pp.63-69
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• 2015

In this study, a 2D hydrodynamic model equipped with critical dry depth scheme was developed to reproduce the flow over staircase. The channel geometry of hydraulic experiment conducted by Ishigaki et al. was generated in the computational space, and the developed model was validated against flow properties such as discharge, velocity and momentum. In addition, the water surface profile and the velocity distribution evolved in flow over two layers staircases were analyzed. When the initial water depth at the upper floor was 0.3 m, the maximum velocity at lower floor was 4.2 m/s, and the maximum momentum was $1.2m^3/s^2$, and its conversion to force per unit width was 1.2 kN/m. This value was equivalent to the hydrostatic force with 50 cm water depth, and evacuation became difficult, as proposed by Ishigaki et al. For the flow over staircases connecting two layers, the maximum run-up height in flat part connecting two layers was approximately two times higher than the initial water depth in upper floor, and the rapid shock wave with sharp front and long tail was propagated.

• 한국수산과학회지
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• 제56권5호
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• pp.676-683
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• 2023

The development of the egg, larvae, and juveniles of Acheilognathus macropterus from the Wicheon stream of Nakdonggang River was investigated for early life history characteristics. The fish used in the study were collected from Wicheon stream located in Bian-myeon, Uiseong-gun, Gyeongsangbuk-do. The fertilized egg was 1.88±0.09 mm (n=30) in long diameter and 1.34±0.06 mm (n=30) in short diameter. After fertilization at a water temperature of 20℃, the egg took 31 h and 40 min to hatch. Newly hatched larvae had an average total length of 3.92±0.13 mm (n=30) and possessed a yolk sac the mouth and anus were not developed. Twenty days after hatching, the postflexion larvae had an average total length of 8.08±0.29 mm (n=30), with the tail tip fully bent at 45° and began feeding. Thirty-three days after hatching, the number of fin stems reached an integer with an average total length of 15.0±1.08 mm (n=30). In this study, differences in the egg size, hatching time, melanophore development period, and distribution location were confirmed between A. macropterus and allied species.

• Asian-Australasian Journal of Animal Sciences
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• 제23권9호
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• pp.1159-1165
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• 2010

Glucose is the main energy source for mammalian cells and its absorption is co-mediated by two different families of glucose transporters, sodium/glucose co-transporters (SGLTs) and facilitative glucose transporters (GLUTs). Here, we report the cloning and tissue distribution of porcine GLUT2. The GLUT2 was cloned by RACE and its cDNA was 2,051 bp long (GenBank accession no. EF140874). An AAATAA consensus sequence at nucleotide positions 1936-1941 was located upstream of the poly $(A)^+$ tail. Open reading frame analysis suggested that porcine GLUT2 contained 524 amino acids, with molecular weight of 57 kDa. The amino acid sequence of porcine GLUT2 was 87% and 79.4% identical with human and mouse GLUT2, respectively. GLUT2 mRNA was detected at highest level in porcine liver, at moderate levels in the small intestine and kidney, and at low levels in the brain, lung, muscle and heart. In the small intestine, the highest level was in the jejunum. In conclusion, the mRNA expression of GLUT2 was not only differentially regulated by age, but also differentially distributed along the small intestine of piglets, which may be related to availability of different intestinal luminal substrate concentrations resulting from different food sources and digestibility.

• 지능정보연구
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• 제20권3호
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• pp.19-43
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• 2014

전체 결과의 80%가 전체 원인의 20%에 의해 일어난다는 파레토 법칙(Pareto principle)은 상위 20%의 핵심 고객에 대한 우선적인 마케팅을 비롯하여 기업 경영의 많은 부분에서 적용되어 왔다. 파레토 법칙과는 대조적으로, 80%의 사소한 다수가 20%의 핵심적인 소수보다 우월한 가치를 창출한다는 롱테일 법칙(Long Tail theory)은 ICT(Information and Communication Technology)의 발전과 함께 새로운 경영 패러다임으로 주목 받아오고 있다. 본 연구의 목적은 경영 현장에서 양대 흐름을 형성해온 이러한 법칙들이 변화무쌍한 글로벌 가상화 환경에서 기업의 핵심적인 성공 요인이라고 할 수 있는 가상 지식 협업에는 어떻게 관련되는지를 규명하는 것이다. 이를 위해, 대표적인 가상 지식 협업 커뮤니티인 위키피디아에서 품질 최상위 등급인 피쳐드 아티클(Featured Article) 레벨로 승급된 2,978개의 아티클에 대한 협업 행위를 분석하였다. 즉, 각 아티클 그룹에서 편집 횟수 기준 상위 20%에 속하는 참여자들의 총 편집 횟수가 전체 편집 횟수에서 차지하는 비율인 파레토 비율(Pareto ratio)이 지식 협업 효율성과 어떤 관계를 가지고 있는지를 도출하였다. 그리고, 이러한 연구를 편집 참여를 통한 지식 공유에 대한 전체적인 불평등 정도를 나타내는 지니 계수(Gini coefficient)의 영향 및 그룹의 작업 특성을 반영하도록 확장하였다. 결과적으로, 지식 공유의 파레토 비율과 지니 계수가 증가하면 지식 협업 효율성도 높아지지만, 이러한 변수들이 일정 수준 이상으로 증가하면 오히려 지식 협업 효율성이 낮아지는 역 U자(inverted U-shaped) 관계가 있음을 확인하였다. 그리고, 이러한 관계는 인지적 노력을 상대적으로 더 많이 요구하는 학문적인 특성의 작업에서 더 민감하게 작용하는 것으로 보인다.

• 유통과학연구
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• 제13권5호
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• pp.53-60
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• 2015

Purpose - The purpose of this paper is to shed light on the importance of the slope and curvature of the volatility curve implied in option prices in the KOSPI 200 options index. A number of studies examine the implied volatility curve, however, these usually focus on cross-sectional characteristics such as the volatility smile. Contrary to previous studies, we focus on time-series characteristics; we investigate correlation dynamics among slope, curvature, and level of the implied volatility curve to capture market information embodied therein. Our study may provide useful implications for investors to utilize current market expectations in managing portfolios dynamically and efficiently. Research design, data, and methodology - For our empirical purpose, we gathered daily KOSPI200 index option prices executed at 2:50 pm in the Korean Exchange distribution market during the period of January 2, 2004 and January 31, 2012. In order to measure slope and curvature of the volatility curve, we use approximated delta distance; the slope is defined as the difference of implied volatilities between 15 delta call options and 15 delta put options; the curvature is defined as the difference between out-of-the-money (OTM) options and at-the-money (ATM) options. We use generalized method of moments (GMM) and the seemingly unrelated regression (SUR) method to verify correlations among level, slope, and curvature of the implied volatility curve with statistical support. Results - We find that slope as well as curvature is positively correlated with volatility level, implying that put option prices increase in a downward market. Further, we find that curvature and slope are positively correlated; however, the relation is weakened at deep moneyness. The results lead us to examine whether slope decreases monotonically as the delta increases, and it is verified with statistical significance that the deeper the moneyness, the lower the slope. It enables us to infer that when volatility surges above a certain level due to any tail risk, investors would rather take long positions in OTM call options, expecting market recovery in the near future. Conclusions - Our results are the evidence of the investor's increasing hedging demand for put options when downside market risks are expected. Adding to this, the slope and curvature of the volatility curve may provide important information regarding the timing of market recovery from a nosedive. For financial product distributors, using the dynamic relation among the three key indicators of the implied volatility curve might be helpful in enhancing profit and gaining trust and loyalty. However, it should be noted that our implications are limited since we do not provide rigorous evidence for the predictability power of volatility curves. Meaning, we need to verify whether the slope and curvature of the volatility curve have statistical significance in predicting the market trough. As one of the verifications, for instance, the performance of trading strategy based on information of slope and curvature could be tested. We reserve this for the future research.

• 수산경영론집
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• 제40권2호
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• pp.49-70
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• 2009

This study proviedes GARCH model(Bollerslev, 1986) to analyze the structural characteristics of price volatility in domestic aquacultural fish market of Korea. As a case study, flatfish and rock-fish are analyzed as major species with relatively high portion in an aspect of production volume among fish captured in Korea. For analyzing, this study uses daily market data (dating from Jan 1 2000 to June 30, 2008) published by the Noryangjin Fisheries Wholesale Market which is located in Seoul of Korea. This study performs normality test on trading volume and price volatility of flatfish and rock-fish as an advanced empirical approach. The normality test adopted is Jarque-Bera test statistic. As a result, first, a null hypothesis that "an empirical distribution follows normal distribution" was rejected in both fishes. The distribution of daily market data of them were not only biased toward positive(+) direction in terms of kurtosis and skewness, but also characterized by leptokurtic distribution with long right tail. Secondly, serial correlations were found in data on market trading volume and price volatility of two species during very long period. Thirdly, the results of unit root test and ARCH-LM test showed that all data of time series were very stationary and demonstrated effects of ARCH. These statistical characteristics can be explained as a reasonable ground for supporting the fitness of GARCH model in order to estimate conditional variances that reveal price volatility in empirical analysis. From empirical data analysis above, this study drew the following conclusions. First of all, from an empirical analysis on potential effects of seasonality and the day of week on price volatility of aquacultural fish, Monday effects were found in both species and Thursday and Friday effects were also found in flatfish. This indicates that Monday is effective in expanding price volatility of aquacultural fish market and also Monday has higher effects upon the price volatility of fish than other days of week have since it has more new information for weekend. Secondly, the empirical analysis led to a common conclusion that there was very high price volatility of flatfish and rock-fish. This points out that the persistency parameter($\lambda$), an index of possibility for current volatility to sustain similarly in the future, was higher than 0.8-equivalently nearly to 1-in both flatfish and rock-fish, which presents volatility clustering. Also, this study estimated and compared and model that hypothesized normal distributions in order to determine fitness of respective models. As a result, the fitness of GARCH(1, 1)-t model was better than model where the distribution of error term was hypothesized through-distribution due to characteristics of fat-tailed distribution, was also better than model, as described in the results of basic statistic analysis. In conclusion, this study has an important mean in that it was introduced firstly in Korea to investigate in price volatility of Korean aquacultural fishery products, although there was partially a limited of official statistic data. Therefore, it is expected that the results of this study will be useful as a reference material for making and assessing governmental policies. Also, it is looked forward that the results will be helpful to build a fishery business plan as and aspect of producer, and also to take timely measures to potential price fluctuations of fishery products in market. Hence, it is advisable that further studies related to such price volatility in fishery market will extend and evolve into a wider variety of articles and issues in near future.

• 천문학회보
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• 제40권2호
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• pp.53.2-53.2
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• 2015

We present preliminary results from a series of observations toward G108.8-00.8, which is one of Planck Cold Clumps and a promising candidate of massive prestellar cores. In the integrated intensity map of SCUBA 850 micron dust continuum emission, highly fragmented structures appear. These are distributed along one long filamentary structure seen in the CO 1-0 and 13CO 1-0 integrated intensity maps obtained with the PMO 13.7 m telescope. The northern part of the filament is divided into two parts, as seen in the CO 2-1, 13CO 2-1, and C18O 2-1 integrated intensity maps obtained with the CSO 10 m telescope. The observations of HCO+ 1-0, N2H+ 1-0, and HCN 1-0 with the IRAM 30 m telescope focus on the northern part of the CSO maps, which show a head-tail structure. NH3 (1,1) also shows similar distribution with IRAM maps. The depletion factors, derived by the comparison between the dust continuum and C18O 2-1 emission, varies from 1.5 to 6 over the region, suggesting different evolutionary status of each component. To study the chemical and physical environments of G108.8-00.8, more detailed analysis is in progress.

• 한국정보시스템학회지:정보시스템연구
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• 제26권4호
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• pp.419-442
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• 2017

Purpose The purpose of this study is to explore the pattern of user response and it's duration time through social media content response analysis. We also analyze the characteristics of content quality factors which are associate with the user response pattern. The analysis results will provide some implications to develop strategies and schematic plans for the operator of regional marketing on the SNS. Design/methodology/approach This study used mixed methods to verify the effects and responses of social media contents on the users who have concerns about regional events such as local festival, cultural events, and city tours etc. Big data analysis was conducted with the quantitative data from regional government SNSs. The data was collected through web crawling in order to analyze the social media contents. We especially analyzed the contents duration time and peak level time. This study also analyzed the characteristics of contents quality factors using expert evaluation data on the social media contents. Finally, we verify the relationship between the contents quality factors and user response types by cross correlation analysis. Findings According to the big data analysis, we could find some content life cycle which can be explained through empirical distribution with peak time pattern and left skewed long tail. The user response patterns are dependent on time and contents quality. In addition, this study confirms that the level of quality of social media content is closely relate to user interaction and response pattern. As a result of the contents response pattern analysis, it is necessary to develop high quality contents design strategy and content posting and propagation tactics. The SNS operators need to develop high quality contents using rich-media technology and active response contents that induce opinion leader on the SNS.