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Competitive Equilibrium with Non-Concavifiable Preferences
Dongchul Won 서울대학교 경제연구소 2001 Seoul journal of economics Vol.14 No.2
The no free lunch condition is neither necessary nor sufficient for the utility set to be closed and bounded in asset markets where the preferred sets do not have the same recession cone. This paper characterizes the utility set with non-concavifiable preferences and provides the existence of competitive equilibrium when the set of efficient allocations is not necessarily bounded.
Effect of Pelvic Compression Taping on Lumbo-Pelvic Muscle Activities during Prone Hip Extension
Dongchul Moon,Juhyeon Jung 국제물리치료연구학회 2021 Journal of International Academy of Physical Ther Vol.12 No.3
Background: Compression of the sacroiliac joint (SIJ) enables lumbo-pelvic muscles to increase pelvic stability and reduce pain. Many previous studies assessed the effects of pelvic compression belts on the stabilization of the lumbar and SIJs. However, there are a lack of studies to date on the effects of pelvic compression taping (PCT). Objectives: To investigate the effects of PCT on the muscle activity of lumbopelvic muscles during prone hip extension (PHE). Design: Pre-post test design. Methods: In total, 19 healthy male and female participants performed PHE with and without PCT. A surface electromyography system was used to record the muscle activity of multifidus, erector spinae, internal oblique abdominal, and gluteus maximus muscles, and the activities of these muscles before and after taping were compared. Results: During PHE, the activities of the multifidus and erector spinae muscles (P<.05) significantly increased after taping, while that of the internal oblique abdominal muscle significantly decreased after taping (P<.05). However, the activity of the gluteus maximums muscle did not significantly increase or decrease after taping (P>.05). Conclusion: PCT for the SIJ improves the stability of the lumbo-pelvic region, and the use of PCT with functional training would lead to positive clinical effects.
Dongchul Kim,Yongduk Choi,Dongseop Lee 한국인사조직학회 2019 한국인사ㆍ조직학회 발표논문집 Vol.2019 No.2
Does a good relationship with leaders always lead to more employee voice? Previous theory and research have suggested that good work-related relationships with leaders (i.e. Leader-member exchange, LMX) result in increased levels of voice behavior as employees often feel obligation to reciprocate by speaking up their ideas proactively. However, this paper challenges the assumption that LMX leads to more voice, and argue that the relationship between LMX and voice is more complex. Drawing on conservation of resource (COR) theory, this study suggests that those who have high-quality of LMX would avoid voice, which is risky behavior, to protect the favorable relationship with his or her leader. Specifically, it is examined that LMX can lead to decreased level of voice through creation of façades of conformity. Also, power distance orientation is considered as a boundary condition that unleashes either the effects of LMX on facades or negative indirect effects of LMX on voice through facades. Multisource data from 66 leaders and 252 of their direct members in Korean companies support the hypothesized model and indicate that LMX is negatively related to voice via facades of conformity. Moreover, as predicted, the moderation and moderated mediation effects of power distance was supported. These findings highlight the importance of considering more complicated relationship between LMX and employee voice, how and when dose it influence employee voice negatively. Theoretical and practical implications are discussed.
Dongchul Sung,Noejung Park 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
We perform {\it ab initio} electronic structure calculations for the metal-carbon nanotube (CNT) interfaces with encapsulated fullerenes (C$_{82}$) or metallofullerenes (La@C$_{82}$). Gold and aluminum layers are chosen as typical examples of metals with a large work function and a small work function, respectively. It is found that the encapsulation of the fullerene species can affect the Schottky barrier height at the metal-CNT interface. We show that the fullerene-derived localized state could weakly pin the metal Fermi level in the gap of the nanotube. We suggest that the transport properties of the metallofullerene-encapsulated CNT should be explained in terms of the Schottky barrier adjustment rather than the band gap reduction model whose validity has been debated in recent publications.
Dongchul Kim,어영선 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.8
Thin-film transmission lines are experimentally characterized in the frequency range from 10 MHzto 110 GHz. Scattering (S-) parameters for several test lines are measured. Then, two importanttransmission line parameters (i.e., the propagation constant and characteristic impedance) are determinedin the measured frequency range. The resonances, which are inevitable in a practicalexperimental environment, are carefully eliminated by de-embedding parasitic effects and by determiningthe frequency-variant dielectric permittivity based on the Debye model. Based on theexperimental work, we showed that the conventional skin-effect model may not be accurate for highfrequencies. Further, the 3-dimensional (3D) numerical field solver does not reflect the radiationloss at high-frequency. Finally, in the millimeter (mm)-wave region, all the three loss mechanismsdue to the skin-effect, dielectric polarization, and electromagnetic radiation have to be taken intoaccount.
The Fundamental Theorem of Asset Pricing with Convex Transaction Costs
Dongchul Won(원동철) 한국계량경제학회 2006 계량경제학보 Vol.17 No.2
본 논문의 목적은 볼록거래비용하에서 자산가격결정의 기본정리를 정립하는 것이다. 아비트라지 가격결정함수는 거래비용의 한계적 영향을 받지 않으며 대형 거래의 평균비용에 의해서 결정된다. 이러한 사실은 가격결정원리가 거래비용의 성질에 관한 최소한의 정보에 의해 파악될 수 있음을 의미한다. 또한 볼록거래비용함수가 아무리 복잡할지라도 가격결정원리는 비례적 거래비용의 경우처럼 단순하고 구체적 형태로 도출된다. 이러한 결과는 거래비용의 한계적 영향, 즉 거래비용함수의 국지적 형태에 좌우되는 균형가격결정이론과 큰 대조를 이룬다. 더구나 아비트라지 부재조건은 자산가격의 존속성과 일치한다. The paper establishes the fundamental theorem of asset pricing (FTAP) with convex transaction costs. The arbitrage pricing rules are independent of the marginal effect of transaction costs and determined by average costs for large transactions. This implies that the pricing rules are characterized by minimal information on the nature of transaction costs. Remarkably, no matter how complex the convex transaction cost functions are, the pricing rules are as simple and concrete as in the case with proportional transaction costs. This result is in sharp contrast to equilibrium pricing theory based upon the knowledge of the marginal effect of transaction costs and therefore, of transaction cost functions. Moreover, the no arbitrage condition is equivalent to viability of asset prices.
Dongchul Kim,Jaehyun Han,Minchae Lee,Myoungho Sunwoo 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Environmental perception such as obstacle detection and tracking is an inevitable requirement for autonomous vehicles. Especially, in order to avoid collisions, autonomous vehicles require a detection and tracking of moving objects (DATMO) such as vehicles and pedestrians. The multiple hypothesis approach (MHA) is most frequently used for DATMO, whereby the MHA generates all possible hypotheses for moving objects. However, the MHA also generates hypotheses for immobile objects such as parked vehicles, bushes, and trees, among others, the result of which is a computational overhead for DATMO as a result of tracking irrelevant hypotheses. The ability to distinguish moving objects from static objects using a laser scanner with an occupancy grid map has been developed previously. In the present study, we utilized this method in order to apply MHA to only moving objects. Using this approach, moving objects were efficiently detected and tracked on a grid map. Furthermore, DATMO on the grid map was effectively implemented in real-time.