• International Area Studies Review
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• v.14 no.1
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• pp.55-76
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• 2010

This paper analyses interaction between yen/dollar exchange rates and NIKKEI index using bivariate GJR-GARCH(1,1) model. The data employed for the study is daily data series for the period of Jan. 4, 1995 through Aug. 30, 2009. One of main findings is that market inefficiency appears in the periods of financial crisis. Second, the volatility of exchange rates and stock returns has more increased in the wake of the volatility shock of the previous period during financial crisis than during non-financial crisis. Third, interestingly, the asymmetric volatility shock by bad news in those markets is bigger in financial crisis period than in non financial crisis. Fourth, in the period of current global financial crisis triggered by subprime mortgage crisis in U.S, volatility shock at the previous period is bigger than that of Asian financial crisis that happened in 1997. Lastly, the correlation between both returns of exchange rates and stock prices turns up positive according to the empirical estimation. This result may come from the fact that Japanese stock market does not have much attraction for international financial investment compared to stock markets of neighbouring countries like China, Korea and so on, while real sector's contribution to the economy is considered more importantly.

• Review of Culture and Economy
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• v.20 no.2
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• pp.149-171
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• 2017

This paper presents empirical findings about the market inefficiency field in the korean horse track. We first use the place betting data instead of the win betting data inevitably depended on by past studies, and discuss the degree of the long shot anomaly and the bettor's risk attitude sequentially in the place betting market. The empirical result of betting simulations using the place winning function in this study reveals persistently higher returns than the expected payoff in korean racetrack betting market. The clear departures from perfect efficiency in horse-racing betting imply that much of the market information is insufficient and less accurate. This market asymmetry aggravates popular speculations exquisitely since people are attracted by the higher odds figures in the racetrack display although those are much uncertain in future. The findings suggest the more objective and credible information of winning possibilities such as the place winning function including the smart information of marginal odds needs to be available to the betting decision of the public, which contributes to reducing the speculative spirit in korean racetrack.

• Journal of Biomedical Engineering Research
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• v.24 no.1
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• pp.37-44
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• 2003

This experimental study is aimed at evaluating the hydrodynamic performance of newly designed self-expandable graft stents under steady flow condition. Two graft stents with different coating materials and a bare TiNi metallic stent for comparison test were used in the experiment. Pressure variation and velocity distribution at the upstream and downstream of the stents were measured at flow rates of 5, 10, and 15 l/min, respectively. Pressure loss due to insertion of the stent increased with increasing flow rate exponentially as expected. At a flow rate of 15 l/min, pressure loss of Polyure-thane(PU)-coated graft stent was 6 times higher than that of TiNi metallic stent, while the pressure loss of a porous Polytetrafluoroethylene(PTFE)-coated graft stent was comparable to a bare TiNi metallic stent. Velocity profiles of the porous PTFE-coated graft stent were similar to those of a bare TiNi metallic stent regardless of flow rate. Furthermore, the velocity profile of PU-coated graft stent revealed an asymmetrical and relatively low central velocity at a higher flow rate than 10 1/min, expecially, where the effects resulted in increases of wall shear stress and normal stress. The worse hydrodynamic behavior of PU-coated graft stent than the other two stents might be attributed to formation of folds due to poor flexibility of coated material when inserting the graft stent into the pipe with a more smaller size, which later gave rise non-symmetry of flow area, increase of surface roughness and jet flow via the crevice between the stent and cylinder wall.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.413-422
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• 2003

We have calculated the power extraction efficiency and the lasing wavelength distribution of index-coupled DFB lasers at threshold for various kL and facet reflectivity combinations, and compared with those above-threshold. The power extraction efficiency increases as the asymmetry of the facet reflectivities increases. The power extraction efficiency above-threshold is slightly larger than that at threshold. Since the relative photon density around the center region increases as kL increases, the power extraction efficiency decreases. The uniformity of the distribution of lasing wavelength over the stop band increases due to the relief of mode degeneracy as the asymmetry of the facet reflectivities increases. In the case of AR-HR combination, the lasing wavelength distributions at threshold are similar to those above-threshold. However, in the case of AR-AR combination, the lasing wavelength at threshold is concentrated on both edges of the stop band, while it is concentrated only on the longer wavelength edge above-threshold. As kL increases, the range of the lasing wavelength distribution increases due to the increase of the stop band. The effect of AR reflectivity on the power extraction and the lasing wavelength distribution is very weak.

• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.52-57
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• 2000

Purpose : The purpose of this study was to investigate the pattern of cerebral response to motor tasks in patients with schizophrenia compared with normal subjects using functional MRI. Materials and methods ; Nine right handed-schizophrenic patients and six right-handed normal subjects were included. We used right hand movement as task. Series of 120 consecutive echo-planar images per section were acquired during three cycles of task and rest activations. Lateralization index of cortical response was measured and compared between patients and normal subjects. Results ; Right hand motor task was associated with greater activation in left sensorimotor cortex than the right in normal subjects. Schizophrenia patients showed relatively decreased activation in left cortex and increased activation in right cortex compared with normal subjects. In one patient, reversed lateralization was noted. Conclusion : Normal hemispheric asymmetry of cortical response to motor task was found in different pattern in schizophrenia. Our result is consistent with functional disturbance of motor circuitry in this disorder. Functional MRI will play an important role in diagnosis and research of this disorder.

• The Korean Journal of Financial Management
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• v.12 no.2
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• pp.95-120
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• 1995

자본시장에서 자산가격결정이론의 대부분은 투자자산의 기대수익률과 변동성이 시간의 흐름에 따라 일정한 것으로 가정하여 왔다. 그러나 최근의 연구 성과에 의하면 주식수익률의 변동성이 동분산이라기 보다는 이분산일 가능성이 높다는 것이다. 1982년 Engle에 의하여 개발된 자기회귀 조건부 이분산모형(ARCH)이 제시된 이래 ARCH형태의 모형개발이 계속 이루어져 왔다. 본 논문은 ARCH형태의 이분산모형 가운데서 EGARCH모형을 이용하여 위험프레미엄과 조건부 이분산과의 관계와 더불어 기대하지 않은 수익률변화와 변동성과의 관계를 규명하고자 노력하였다. 1980년에서 1994년까지의 주가자료를 전체기간과 세부기간(4기간)으로 분류하여 기술 통계량 분석을 행하고, 종합주가지수초과수익률, 동일 가치 가중지수초과수익률, 대형주 주가지수초과수익률, 소형주 주가지수초과수익률에 대하여 EGARCH모형 을 적용하여 실증분석 하였다. 그 결과 위험프레미엄과 조건부 이분산은 시간이 지남에 따라 일정한 관계를 보여주지 못하고 있어 투자자의 위험회피도(危險回避度)가 변화함을 보여주었다. 기대하지 않은 수익률변화와 변동성 관계에서는 기대하지 않은 음(陰)(-)의 주식수익률이 기대하지 않은 양(陽)(+)의 주식수익률보다 상대적으로 더 큰 변동성을 가져오는 것으로 보여 우리나라 주식시장에서 주식수익률의 변동성 정보의 비대칭 반응효과가 존재하는 것으로 나타났다.

• Science of Emotion and Sensibility
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• v.8 no.1
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• pp.47-54
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• 2005

This study is aimed to inspect how the different sensitivities in Behavioral activation system(BAS) and behavioral inhibition system(BIS) modulate on the properties of physiological responses stimulated by positive or negative affective sound. We measured the electroencephalogram(EEG) and electrocardiogram (ECG) of 32 students, consisted of four groups depending on the BAS and BIS sensitivities, during listening to meditation music or noise. The EEG was recorded at Fpl and Fp2 sites and Power spectral density(PSD) of HRV was derived from the ECG, and the power of HRV was calculated for 3 major frequency ranges(low frequency[LF], medium frequency and high frequency[HF]). After listening to music or noise, subjects reported the affect induced by the sound. For EEG, the power in the alpha band at Fp2, especially in the alpha-2 band(9.0-11.0 Hz) increased during the subjects listening to music, while the power at Fpl increased during noise. During listening to meditation music, there is a tendency that the left-sided activation in prefrontal cortex(PFC) is positively correlated with the difference of BAS(Z)-BIS(Z). During listening to noise, there is a tendency that the right-sided activation in PFC is dominant in case any of the sensitivity of BAS or BIS is high. For HRV, we found that the index of MF/(LF+HF), during listening to music, was higher significantly in the individuals with a low BIS but high BAS than in the individuals with a low sensitivity both BIS and BAS individuals. With high BIS, regardless of the BAS sensitivity, the difference of this index values was not significant. From these results we suggest that the physiological responses of different individuals in BAS and BIS react differently under the same emotionally provocative challenge.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2017.11a
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• pp.779-797
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• 2017

완전자본시장에서는 기업의 투자활동이 자금조달 방법과 무관하지만, 현실경제에서는 정보비대칭성으로 인해 외부자금 조달이 제약되는 금융제약 현상이 발생할 수 있다. 금융제약 현상은 기업의 규모가 작거나, 업력이 짧을수록, 그리고 하이테크 산업의 기업일수록 심화된다는 것이 일반적인 시각이다. 우리나라 코스닥 시장은 상대적으로 금융제약에 노출되는 기업들이 주로 상장되는 시장으로, 본 연구는 코스닥 상장이 개별 기업의 금융제약을 완화하는데 효과가 있었는지에 대해서 분석하였다. 분석 결과 금융제약 완화효과가 확인되었으며, 이러한 효과가 통합 증권선물거래소(현(現) 한국거래소)가 출범 후 강화된 것으로 나타났다. 이는 투자자 보호 측면의 체질개선이 거래량 및 코스닥 지수 등에는 일부 부정적이었을 수 있으나, 시장 안정화를 통해 기업의 자금조달을 도왔다는 것을 시사한다.

• The Korean Journal of Financial Management
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• v.27 no.1
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• pp.157-180
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• 2010

We try to check empirically whether the Korean banks produce valuable information for the firms listed in KOSDAQ. The sample covers 164 KOSDAQ firms which disclosed long-term bank loans for the period of October 2004 and March 2006. The result shows no abnormal stock returns from bank loan disclosures while the bond issuance indicates a negative abnormal return. In addition, when we control the effect of different debt levels of sample firms, we could not find any statistically significant effect of all types of borrowings. Results suggest that bank borrowings do not convey any favorable information on stock return and, as a result, bank loan is just one of several financing tools rather than a special event conveying good news for the firm under asymmetric information situation.

• The KIPS Transactions:PartD
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• v.8D no.2
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• pp.132-144
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• 2001

The broadcast environment is asymmetric communication aspect that is typically much greater communication capacity available from server to clients than in the opposite direction. In addition, most of mobile computing systems only allow the generation of read-only transactions from mobile clients for retrieving different types of information such as stock data, traffic information and news updates. Since previous concurrency control protocols, however, do not consider such a particular characteristics, the performance degradation occurs when those schemes are applied to the broadcast environment having quite a high data contention. In this paper, we propose OCC/2VTS (Optimistic Concurrency Control based on 2-Version and TimeStamp) that is most appropriate for broadcast environment. OCC/2VTS lets each client process and commit query transactions for itself by using two version data in cache. If the values of appropriate data items are not changed twice by invalidation report after a query transaction starts, the query transaction is committed safely independent of commitment of update transactions. OCC/2VTS decreases the number of informing server for the purpose of commitment. Due to broadcasting the validation reports including updated recent values, it reduces the opportunity of requesting a recent data values of server as well. As a result, OCC/2VTS makes full use of the asymmetric bandwidth. It also improves transaction throughput by increasing the query transaction commit ratio as much as possible.