• 한국산학경영학회:학술대회논문집
• /
• 2004.11a
• /
• pp.4-22
• /
• 2004

The Internet provides a new distribution channel of digital contents for conventional media firms such as newspaper, magazine and encyclopedia publishers and broadcasting companies with very low marginal production and distribution cost. In comparison to traditional offline channel, there have been various revenue models in online content markets such as advertising model, subscription model, affiliation fee model, etc. In the earlier of the Internet era, most of online content firms provided their services free in order to boost offline revenue or they depend on advertising revenue sources in lieu of attaining revenue from their contents. However, as many online content firms are confronted with many difficulties in attaining revenues from online advertising model, they began to charge their contents. This paper shows why they charge their contents and explores entry conditions when conventional firms enter online content markets. And also this paper discusses managerial implications related to pricing strategies in online content markets.

• Journal of Astronomy and Space Sciences
• /
• v.19 no.1
• /
• pp.1-6
• /
• 2002

Recently, one interesting possibility is proposed that a magnetar can be a progenitor of short and hard gamma-ray bursts (GRBs). If this is true, one may expect that the short and hard GRBs, at least some of GRBs in this class, are distributed in the Euclidean space and that the angular position of these GRBs is correlated with galaxy clusters. Even though it is reported that the correlation is statistically marginal, the observed value of < $V/V_{max}$ > deviates from the Euclidean value. The latter fact is often used as evidence against a local extragalactic origin for short GRB class. We demonstrate that GRB sample of which the value of < $V/V_{max}$ > deviates from the Euclidean value can be spatially confined within the low value of z. We select very short bursts (TgO < 0.3 sec) from the BATSE 4B catalog. The value of < $V/V_{max}$ > of the short bursts is 0.4459. Considering a conic-beam and a cylindrical beam for the luminosity function, we deduce the corresponding spatial distribution of the GRB sources. We also calculate the fraction of bursts whose redshifts are larger than a certain redshift z', i.e. f>z'. We find that GRBs may be distributed near to us, despite the non-Euclidean value of < $V/V_{max}$ >. A broad and uniform beam pattern seems compatible with the magnetar model in that the magnetar model requires a small $z_{max}$.

• Proceedings of the KIEE Conference
• /
• 1999.07b
• /
• pp.991-993
• /
• 1999

This study proposed a new algorithm to assess autonomic function activity using Time-Frequency Representation(TFR). TFR is a way of describing the time-valiant energy of a signal. A discrete Wigner representation that is capable of filtering out any cross terms occuring in the Wigner-Ville Distribution(WVD) is used for time-variant energy distribution of heart rate variability(HRV) signals. And the marginal condition are evaluated to estimate power spectrum of HRV signals. The proposed algorithm showed that estimated power spectrum of HRV signals well describe the autonomic nerve system function and also showed the dynamics of autonomic nervous system response.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.87.1-87.1
• /
• 2012

We use three-dimensional magnetohydrodynamic simulations to investigate how the dynamic state of emerging magnetic field is related to the twist of field lines. Emergence of magnetic field is considered as one of the key physical process producing solar activity such as flares, jets, and coronal mass ejections. To understand these activities we have to know dynamic nature and electric current structure provided by emerging magnetic field. To demonstrate dynamic nature of field lines, we focus on the factors such as curvature of magnetic field line and scale height of magnetic field strength. These factors show that strong twist case forms two-part structure in which the central part is close to a force-free state while the outer marginal part is in a fairly dynamic state. For weak twist case, it still shows two-part structure but the tendency becomes weaker than strong twist case. We discuss how the curvature distribution affects the dynamic nature of emerging magnetic field. We also investigate electric current distribution provided by emerging field lines to show a possible relation between electric current structure and sigmoid observed in a preflare phase.

• The Korean Journal of Applied Statistics
• /
• v.30 no.2
• /
• pp.203-213
• /
• 2017

We study estimation and inference of joint conditional distributions of bivariate longitudinal outcomes using regression models and copulas. We consider a class of time-varying transformation models and combine the two marginal models using Gaussian copulas to estimate the joint models. Our models and estimation method can be applied in many situations where the conditional mean-based models are inadequate. Gaussian copulas combined with time-varying transformation models may allow convenient and easy-to-interpret modeling for the joint conditional distributions for bivariate longitudinal data. We apply our method to an epidemiological study of repeatedly measured bivariate cholesterol data.

• Journal of the Korean Solar Energy Society
• /
• v.31 no.6
• /
• pp.23-31
• /
• 2011

The wind energy is one of the most prospective resources in renewable energy. However, the WTGS shouldn't be installed indiscriminately because the power system can be negatively influenced by a variable and uncertain nature of the wind energy. It is the reason why it has to be limited to install the WTGS thoughtlessly mentioned above that support the importance of the maximum penetration limit of wind power. It may required that power system operators suggests a new way of power system operation as percentage of the WTGS increase in the existing power system. The wind power is fixed in a limited area, so using rate of the wind power will be increased by installing additional WTGS. In this paper, we have studied on economic evaluation of the wind capacity increased by restricting the output of the WTGS as the way to increase the wind capacity.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.414-414
• /
• 2015

최근 지구온난화로 인한 기상변동성 증가로 인해 극한기후현상의 발생빈도가 점차 증가하고 있으며 유역단위의 수자원을 효율적으로 운영하는데 문제점을 해소하고자 다양한 측면에서 체계적인 수자원 운영을 위한 연구가 이루어지고 있다. 수공구조물을 설계하는데 있어서 가장 일반적인 가정 사항은 수문모형에 사용되는 강우의 빈도와 유출의 빈도가 동일하다는 가정에 근거한다. 즉, 유역의 초기함수조건, 강우강도, 강우의 시간적 분포와 관계없이 동일한 빈도로 고려되는 문제점이 있다. 이러한 점에서 비교적 장기간의 자료를 확보하고 있는 계측유역에 대해서 다변량 확률밀도함수를 적용하여 비선형관계를 고려한 수문빈도해석기법을 개발하고자 한다. 본 연구에서는 이변량 분석기법(bivariate analysis) 중 전통적인 이변량 분포에 비해 주변분포형(marginal distribution)을 자유롭게 선택할 수 있는 장점이 있는 추계학적 Copula 모형을 활용하여 댐 및 저수지 상류유역의 강우량과 유입량을 대상으로 이변량 분석을 수행하고자 한다. 최종적으로 비선형 관계에 있는 강수량과 유출량 사이에 이변량 빈도해석 모형을 개발하고 기존 해석방법과의 종합적인 비교를 실시하였다.

• 한국해양학회지
• /
• v.29 no.3
• /
• pp.287-295
• /
• 1994

The relationship between temperature profile and backscattering strength(S/SUB y/) computed by the ADCP data is studied in warm eddy of the southwestern parts of the East Sea of Korea in April, 1993. The result shows that S/SUB y/ with depth in N-S direction shows a symmetric shape that is almost the same as the warm eddy. But the profile of S/SUB y/ with depth in N-S direction shows a symmetric shape that is almost the same as the warm eddy. But the profile of S/SUB y/ in E-W direction shows asymmetric shape where the S/SUB y/ of the eastern parts is smaller than that of western parts. The asymmetric distribution may be due to the migration of a large number of scatterer(mainly zooplankton) carried by EKWC(East Korea Warm Current). Profile of the S/SUB y/ is similar to the temperature with depth in the ADCP data of CREAMS 93(Circulation Research of the East Asian Marginal Seas).

• Food Science of Animal Resources
• /
• v.37 no.3
• /
• pp.469-476
• /
• 2017

This study analyzed consumers' preferences and price sensitivity to native chickens. A survey was conducted from Jan 6 to 17, 2014, and data were collected from consumers (n=500) living in Korea. Statistical analyses evaluated the consumption patterns of native chickens, preference marketing for native chicken breeds which will be newly developed, and price sensitivity measurement (PSM). Of the subjects who preferred broilers, 24.3% do not purchase native chickens because of the dryness and tough texture, while those who preferred native chickens liked their chewy texture (38.2%). Of the total subjects, 38.2% preferred fried native chickens (38.2%) for processed food, 38.4% preferred direct sales for native chicken distribution, 51.0% preferred native chickens to be slaughtered in specialty stores, and 32.4% wanted easy access to native chickens. Additionally, the price stress range (PSR) was 50 won and the point of marginal cheapness (PMC) and point of marginal expensiveness (PME) were 6,980 won and 12,300 won, respectively. Evaluation of the segmentation market revealed that consumers who prefer broiler to native chicken breeds were more sensitive to the chicken price. To accelerate the consumption of newly developed native chicken meat, it is necessary to develop a texture that each consumer needs, to increase the accessibility of native chickens, and to have diverse menus and recipes as well as reasonable pricing for native chickens.

• Geophysics and Geophysical Exploration
• /
• v.5 no.4
• /
• pp.262-271
• /
• 2002

This study presents a practical procedure for the Bayesian inversion of geophysical data. We have applied geostatistical techniques for the acquisition of prior model information, then the Markov Chain Monte Carlo (MCMC) method was adopted to infer the characteristics of the marginal distributions of model parameters. For the Bayesian inversion of dipole-dipole array resistivity data, we have used the indicator kriging and simulation techniques to generate cumulative density functions from Schlumberger array resistivity data and well logging data, and obtained prior information by cokriging and simulations from covariogram models. The indicator approach makes it possible to incorporate non-parametric information into the probabilistic density function. We have also adopted the MCMC approach, based on Gibbs sampling, to examine the characteristics of a posteriori probability density function and the marginal distribution of each parameter.