Yoonbai Kim

Classical geometry of de Sitter spacetime is reviewed in arbitrary dimensions. Topics include coordinate systems, geodesic motions, and Penrose diagrams with detailed calculations.

본 연구는 중소기업의 기술혁신을 유도하기 위한 정부의 정책 수단인 연구개발지원과 규제장벽이 실제 중소기업의 기술혁신에 미치는 영향에 대한 고찰을 목적으로 한다. 대부분의 기존 연구들은 연구개발지원에 대한 내생성을 고려하지 않았으며, 규제의 경우 연구자마다 상이한 결론을 도출하였기 때문에 이를 극복하기 위하여 실증적 연구를 추진하였다. 중소기업 1,223개를 대상으로 연구를 추진하여, 로직분석, 음이항분석, 2SLS분석을 수행하였다. 분석결과는 첫째, 정부 연구개발지원의 내생성을 고려하여도 실제 기술혁신효과가 존재하는 것으로 나타났고, 둘째, 규제가 기술혁신에 긍정적인 영향을 미치는 것으로 나타나 Porter의 이론을 지지하였다. 이와 같은 결과는 다음과 같은 시사점을 갖는다. 중소기업이 가지는 기술개발 환경의 취약성 때문에 정부의 연구개발지원은 기술혁신 유도에 있어 중요한 역할을 한다는 것이다. 그리고 정부는 무조건적인 규제 철폐보다는 중소기업에 대한 지원과 더불어 적절한 규제를 추

An empirical analysis study applied to evaluate the effect of critical factors for technology transfer. The research aims to suggest ways of political support in order to facilitate technological transfer and commercialization of public research institute’technology. Based on previous researches, it is determined that five critical factors which effect on technology commercialization. These critical factors are used to derive the order of priority, attribute of the success, and failure factors.

A bstract We study supersymmetric inhomogeneous field theories in 1+1 dimensions which have explicit coordinate dependence. Although translation symmetry is broken, part of supersymmetries can be maintained. In this paper, we consider the simplest inhomogeneous theories with one real scalar field, which possess an unbroken supersymmetry. The energy is bounded from below by the topological charge which is not necessarily nonnegative definite. The bound is saturated if the first-order Bogomolny eq

We study the axially symmetric static solitons of the O(3) nonlinear $\ensuremath{\sigma}$ model coupled to (2+1)-dimensional anti--de Sitter gravity. The obtained solutions are not self-dual under a static metric. The usual regular topological lump solution cannot form a black hole even though the scale of symmetry breaking is increased. There exist nontopological solitons of half integral winding in a given model, and the corresponding spacetimes involve charged $\mathrm{Ba}\mathrm{n}\ifmmode

As global competition is increasing and enterprise environment is rapidly changing in the aftermath of the development of information and communications, many companies have recognized the necessity to sustain innovation. To enable such innovation activities, many companies are trying to utilize startups' entrepreneurial culture in order to quickly adjust to the changes and enter new markets. 'Entrepreneurial orientation' is recognized as a decision making strategy of entrepreneurship in existin

국내 이동통신 서비스 시장은 급속하게 발전해왔다. 이러한 성장에 맞춰 WCDMA 서비스가 중요한 성장 동력으로 기대했으나 해외에 비해 국내 보급률은 더딘 실정이다. 하지만 HSDPA의 상용화가 이루어지면서 정체된 WCDMA 단말기의 수요를 이끌 것으로 예상된다. 따라서 신규 WCDMA 서비스의 수요를 예측하고 그에 맞는 새로운 이동통신 사업전략을 세우는 것이 필요할 것이다. 본 논문은 이동통신 단말기의 가격과 성능에 따른 소비자의 구매 효과를 반영하고, 변형된 Lotka-Volterra 예측 모형을 개발하여 향후 WCDMA 서비스 가입자를 예측하였다.

High level of accuracy in forecasting heat demand of each district is required for operating and managing the district heating efficiently. Heat demand has a close connection with the demands of the previous days and the temperature, general demand forecasting methods may be used forecast. However, there are some exceptional situations to apply general methods such as the exceptional low demand in weekends or vacation period. We introduce a new method to forecast the heat demand to overcome thes

Korea gas corporation (KOGAS) is responsible for the whole sale of natural gas in the domestic market. It is important to forecast the daily demand of city gas for supply and demand control, and delivery management. Since there is the autoregressive characteristic in the daily gas demand, we introduce a modified autoregressive model as the first step. The daily gas demand also has a close connection with the outdoor temperature. Accordingly, our second proposed model is a temperature-based model

Major ports in Northeastern Asia engage in fierce competition to attract transshipment traffic volume. Existing time series analyses for analyzing port competition relationships examine the types of competition and relations through the signs of coefficients in cointegration equations using the transshipment traffic volume results. However, there are cases for which analyzing competing relationships is not possible based on the results of the transshipment traffic volume data differences and lim

We analyze homogeneous anisotropic cosmology driven by the dilaton and the self-interacting ``massive'' antisymmetric tensor field which are indispensable bosonic degrees with the graviton in the NS-NS sector of string theories with $D$-branes. We found the attractor solutions for this system, which show the overall features of general solutions, and confirmed it through numerical analysis. The dilaton possesses the potential due to the presence of the $D$-brane and the curvature of extra dimens

We discuss the cosmological implications of an antisymmetric tensor .eld when it experiences a kind of \Higgs mechanism," including nonlocal interaction terms, on D-branes. Even when a huge magnetic-condensation-inducing anisotropy is assumed in the early universe, the expansion of the universe leads to an isotropic B-matter-dominated universe.

We consider Hoˇrava-Lifshitz gravity coupled to the electrostatic field of a point charge, and show that the static solutions describe a space with a surplus (or deficit) solid angle. Unlike in general relativity, appearance of a surplus angle seems generic in Hoˇrava-Lifshitz gravity. We discuss possible astrophysical effects due to a surplus angle.

Managing a call center is a complex and diverse challenge. Call center becomes a very important contact point and a data ware house for successful CRM. Improving performance of call center is critical and valuable for providing better service. In this study we applied forecasting technique to estimate incoming calls and ProModel based simulation model to enhance performance of a mobile telecommunication company's call center. The simulation study shows reduction in managing cost and better custo