• Journal of Mechanical Science and Technology
• /
• 제15권6호
• /
• pp.764-775
• /
• 2001

Oscillartory thermocapillary flow of high Prandtl number fluids in the half-zone configuration is investigated. Based on experimental observations, one oscillation cycle consists of an active period where the surface flow is strong and the hot corner region is extended and a slow period where the opposite occurs. It is found that during oscillations the deformation of free surface plays an important role and a surface deformation parameter S correlates the experimental data well on the onset of oscillations. A scaling analysis is performed to analyze the basic steady flow in the parametric ranges of previous ground-based experiments and shows that the flow is viscous dominant and is mainly driven in the hot corner. The predicted scaling laws agree well with the numerical results. It is postulated that the oscillations are caused by a time lag between the surface and return flows. A deformation parameter S represents the response time of the return flow to the surface flow.

• 한국농공학회지
• /
• 제37권E호
• /
• pp.72-78
• /
• 1995

To support some knowledge in planning irrigation system, short or long-term irrigation scheduling or determining irrigation reservoir capacity, it is necessary to estimate peak irrigation requirements and seasonal distribution of water demands for various return periods. In this paper Dry Day Index and Probable Evapotranspiration were evaluated to decide seasonal consumptive use of paddy rice for a design year using several decades' daily rainfall data and 5 years'('82~'86) actual evapotranspiration data, respectively. To obtain Dry Day Index that is defined as the number of probable dry days for a given period, Slade unsymmetrical distribution function was adopted. Dry Day Index was analysed for 5 and 10-day intervals. Each of them was evaluated with return periods of 1, 3, 5, 10 and 20 year. Their singnificance was tested by X$^2$ method. Based on these values, the Probable Evaportanspiration, that is the average daily ET both in dry days and rainy days during a given period, was estimated. Crop coefficient was also determined by the modified Penman equation proposed by Doorenbos & Pruitt.

• 산업기술연구
• /
• 제22권B호
• /
• pp.231-240
• /
• 2002

The rational method of estimating peak flow is used largely for the simplicity. But the accuracy of rational method is not easy to estimate, because the rational method is analyzed by the deterministic point or view and the runoff coefficients of the rational method are proposed from other countries. In this study the rational method is analyzed by the probabilistic way to be a more reliable method. The runoff coefficient is regarded to parameter that changes the probabilistic rainfall to the peak flow. The runoff coeffient for each return period is analyzed to be a reliable index which is used to estimate the peak flow of ungauged natural catchments.

• Journal of the Korean Data and Information Science Society
• /
• 제14권4호
• /
• pp.805-815
• /
• 2003

This study examines two hypothesis regarding return generating process of corporate bonds: the trading day hypothesis and calendar day hypothesis. To differentiate two hypothesis ANOVA(analysis of variance) and regression analysis were used. If the statistical result can not reject calendar day hypothesis, it implies that there is weekend effect. The statistical result didn't support any particular hypothesis for the period of September 7th, 1999 through December 31, 2002. However, corporate bonds were supporting calendar day hypothesis for the period of October 9, 2000 through December 31, 2002. The result indicates that the Korean corporate bond market got through the impact of IMF.

• Coupled systems mechanics
• /
• 제2권1호
• /
• pp.111-126
• /
• 2013

The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. A nonlinear response analysis of a fixed offshore platform under structural and wave loading is presented, the structure is discretized using the finite element method, wave plus current kinematics (velocity and acceleration fields) are generated using 5th order Stokes wave theory, the wave force acting on the member is calculated using Morison's equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the 1-yr return period wave and must be able to survive the 100-yr return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore platform.

• 한국환경보건학회지
• /
• 제22권4호
• /
• pp.33-42
• /
• 1996

This research is to show the application of runoff model and runoff analysis of urban storm drainage network. the runoff models that were used for this research were RRL, ILLUDAS, and SWMM applicative object basin were Geucknak-chun and Sangmu drainage basin located in Seo-Gu, Kwangju. The runoff analysis employed the design storm that distributed the rainfall intensity according to the return period after the huff's method. The result from the comparative analysis of the three runoff models was as follows The difference of peak runoff by return period was 20-30% at Sangmu drainage area of $3.17 Km^2$, while less than 10% at Geucknak-chun drainage area of $12.7 Km^2$. The peak runoff were similar to all models. At the runoff hydrograph the times between rising and descending points were in the sequence of RRL, ILLUDAS and SWMM, but the peak times were similar to all models. The conveyance coefficient to examine the conveyance of the existing drainage network was 0.94-1.37, which means insecure, in Geucknak-chun drainage basin and 0.69-1.16, which means secure, in sangmu drainage basin.

• 국제지역연구
• /
• 제20권3호
• /
• pp.123-144
• /
• 2016

This paper investigates the linkages between returns both in foreign exchange and stock markets, and uncertainties in two markets using daily data for the period of 16 July 2004 to 30 June 2014 in Nepalese economy. Four hypotheses are tested about how uncertainty influences the stock index and exchange rates. From the empirical results, a bivariate EGARCH-M model is the best to explain the volatility in the two markets. There is a negative relationship from the exchange rates return to stock price return. Empirical results do provide strong empirical confirmation that negative effect of stock index uncertainty and positive effect of exchange rates uncertainty on average stock index. GARCH-in-mean variables in AR modeling are significant and shows that there is positive effect of exchange rates uncertainty and negative effect of stock index uncertainty on average exchange rates. Stock index shocks have longer lived effects on uncertainty in the stock market than exchange rates shock have on uncertainly in the foreign exchange market. The effect of the last period's shock, volatility is more sensitive to its own lagged values.

• 한국수자원학회논문집
• /
• 제44권11호
• /
• pp.889-902
• /
• 2011

본 연구에서는 한반도에서 발생했던 과거 가뭄사상의 정량적 평가를 위한 가뭄심도-지속기간-생기빈도(Severity-Duration-Frequency, SDF) 곡선을 유도하기 위해서 가뭄지수를 이용한 빈도해석을 실시하였다. 분석지점으로는 4대강 유역을 중심으로 하는 기상청 산하의 서울, 대전, 대구, 광주, 부산관측소를 선정하였으며 강수자료는 1974~2010년(37년)의 강수 자료를 이용하였다. 가뭄빈도해석에는 기상학적 가뭄지수인 SPI (Standardized Precipitation Index)를 선정하였으며 확률분포형에 대한 적합도 검정에서는 일반극치분포(GEV, Generalized Extreme Value)가 최적의 확률분포형으로 선정되었다. 가뭄지수의 빈도해석 통하여 유도된 주요 관측소별 SDF (Severity-Duration-Frequency) 곡선을 이용하여 과거의 주요 가뭄사상에 대한 재현기간을 제시하였으며 1994~1995년 가뭄의 경우 남부지방을 중심으로 하는 극심한 가뭄으로서 광주관측소에서는 50~100년, 부산관측소에서는 100~200년의 높은 재현기간을 나타내었다. 그밖에 1988~1989년 가뭄의 경우 서울관측소에서는 300년의 재현기간을 나타내었다.

• 한국산학기술학회논문지
• /
• 제15권12호
• /
• pp.7093-7100
• /
• 2014

본 연구의 목적은 산업재해 근로자의 노동시장이행과 관련한 요인들을 분석하는 것이다. 이를 위하여 근로복지공단이 주관하는 제 1차 산재보험패널조사 데이터를 활용하였다. 주요 연구 결과로 첫째, 요양기간 종료 후 비경제활동인구와 실직 중인 대상자가 각각 7.2%, 22.3%에 이르렀다. 둘째, 새로운 일자리로 복귀한 이들 중 기존에 담당하고 있던 직종과 다른 직종에 근무하는 비중이 31.5%였다. 산업재해로 인하여 직장과 직종이 동시에 바뀌는 산재근로자의 노동시장이행 성격을 보여준다. 셋째, 산재 근로자의 노동시장 이행 중 일자리 복귀여부와 관련한 요인을 살펴보면 남성, 낮은 연령대, 교육연수가 높을수록, 요양기간이 짧을수록, 업무수행능력에 대한 주관적 평가가 좋을수록 유의미한 관련성을 보여주었다. 산재 전직장의 규모와 종사상 지위도 관련성을 보여주었다. 직업훈련 경험자 중 일자리로 복귀하지 못한 사람들의 비중이 상대적으로 높았고 장해등급 정도는 관련성을 보여주지 않았다. 마지막으로 분석결과를 토대로 산재근로자의 노동시장이행 각 단계를 고려하여 이행노동시장 관점에서 만들어진 정책의 필요성을 제시하였다.

• 재무관리연구
• /
• 제22권2호
• /
• pp.135-164
• /
• 2005

개인투자자 10,000명의 1998년부터 2003년까지 6년간의 거래자료와 잔고자료를 분석한 결과, 개인투자자들은 총수익률(gross return) 기준으로 연간 12.3%의 수익률을 실현한 것으로 나타났다. 동기간에 거래소 시장의 가치가중평균수익률은 13.6%였으며 코스닥 시장을 포함하는 종합시장수익률은 9.7%를 기록하였다. 그러나 거래비용을 고려한 순수익률(net return)은 연간 8.3%로 하락하여 시장수익률보다 크게 낮은 것으로 나타났는데, 연간 270%가 넘는 거래 회전율이 투자성과에 부정적인 영향을 미친 탓이라 할 수 있다. 특히 잔고규모별 초과수익률 분석에서는 투자금액이 상위 20%에 속하는 투자자들은 시장수익률과 비슷한 수준의 수익률을 얻은 반면, 나머지 80%의 투자자들은 시장수익률과 커다란 차이를 보였는데, 왜 많은 개인 투자자들이 시장을 떠나는지를 확인시켜 주는 결과이다. 특기할 사항은 과잉확신으로 인해 거래량이 증가하고 기대효용은 낮아진다는 과잉확신 모형을 지지한다는 점이다. 분석대상인 개인투자자들은 고 베타 주식과 소형주와 가치주를 선호하는 것으로 나타났다.