• 대한토목학회논문집
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• 제29권6B호
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• pp.513-526
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• 2009

홍수피해를 줄이기 위해 적정한 설계빈도에 맞는 치수대책을 수립한다. 일반적으로 설계빈도는 지역의 현황, 중요도뿐만 아니라 확률강우량 등을 반영한다. 따라서 본 연구에서는 최근 10년간 주요 호우사상에 의해 홍수피해가 발생한 지역을 대상으로 지속시간별로 최대강우량의 빈도를 산정하였다. 그리고 빈도별 확률강우량을 초과하는 강우사상의 시간적 특성을 분석하기 위해 초과강우량과 초과횟수 및 단위초과강우량을 산정하여 변동성과 경향성 분석을 수행하였다. 또한 강우관측소의 위치와 시간강우량 특성을 이용해 군집분석을 실시하고 강우관측소를 군집화 하였다. 군집된 지역을 대상으로 평균초과강우량과 평균초과횟수 및 평균단위초과강우량을 산정하였고, 군집지역별 초과강우량과 초과횟수에 대해 변동성 및 경향성을 분석을 실시하여 시간적 변화를 비교하였다.

• 노동경제논집
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• 제27권3호
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• pp.75-111
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• 2004

현 연구에서는 NLSY 데이터를 이용하여 개개인이 노동시장에 진입한 이래로 겪은 모든 실직 및 실업 경험을 추출하고, 이를 바탕으로 특정 시점에서의 임금이 그 이전에 겪었던 실직의 횟수와 누적실업기간에 어떻게 영향을 받는가를 분석하였다. 기존의 연구들과는 달리 현 연구에서는 1회의 실업기간이 아닌 누적실업기간의 효과를 분석하였으며 나아가 실직 횟수와 누적 실업기간 중 어느 변수가 임금에 보다 큰 부정적 영향을 주는가를 분석하였다. 실직 횟수와 누적실업기간을 동시에 설명변수로 포함시킬 경우 남성 표본에서는 누적실업기간만이 유의하게 임금을 낮추는 것으로 나타나는 것과 대조적으로 여성 표본에서는 실직 횟수만이 임금에 부정적인 영향을 주는 것으로 나타났다. 남성의 경우 누적실업기간이 한 달 더 길어지면 임금은 0.4% 낮아지는 것으로 나타났으며 이 추정치는 표본 제약을 다양하게 바꾸고 추정모형을 달리하여도 변함 없이(robust) 나타났다. 한편 여성의 경우 추가적인 1회의 실직 경험이 가져다 주는 임금의 하락은 2%를 상회하는 것으로 나타났다.

• International Journal of Industrial Entomology and Biomaterials
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• 제10권2호
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• pp.87-94
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• 2005

Mating is an essential behavioural social event in the life cycle of silkworm, Bombyx mori (L.) for the perpetuation of population. A number of intrinsic and extrinsic factors and events of significant importance are involved in successful mating and egg deposition by an adult silk moth which besides biochemical, physiological and environmental factors also includes attraction of reproductively competent male and female moth for mating, duration and frequency of mating, age of moth at the time of mating, reuse of male moth in the production of eggs etc. An attempt has been made in this review article to elucidate briefly the behaviour of male towards female moth after eclosion, impact of duration and frequency of mating on egg deposition and oviposition, reuse of mated male moth in the production of quality and quantity eggs etc. in the silk-worm, B. mori and its significance in silkworm seed production.

• 한국주거학회논문집
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• 제20권3호
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• pp.69-76
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• 2009

The Storm Water Management Model(SWMM) by EPA is a dynamic rainwater-runoff simulation model used for single event or long-term simulation of runoff quantity and quality from primarily urban areas. The SWMM simulation program is operated by the site area, the weather date, conduit plan etc. on reference region. The purpose of this study was to analyze flood area, the duration of flooded and surcharged on the reference region. Without rainwater stored tank, the area of flooded and surcharged on reference area is similar to the area of reference region. But, With rainwater stored tank, the area of flooded and surcharged on reference area is much reduced compared to without rainwater stored tank. According to SWMM simulation results, the rainwater stored tank is located closer to site is more effective for reduction of duration of flooded and surcharged and flow rate.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.47-55
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• 1998

A new ignition system concept was developed to improve ignition performance, accuracy of control and the reliability of the ignition system. The new ignition system has ho호 frequency discharge characteristics with 1.5-2.0 ms discharge duration, in place of the usual solitary longer duration event. We applied the system to a commercial engine to study its influence on the maximum combustion pressure attained during the cycle, when this peak pressure occurred, imep, variation rate of the engine speed and the flammability limit of a lean mixture. In this study, we clarified that the new ignition system had a beneficial effect of the lean mixture flammability limit. Also for a given mixture strength we found that the mew ignition system gave a higher peak cylinder pressure than in the case of the conventional ignition system.

• 한국건설관리학회논문집
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• 제6권1호
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• pp.73-79
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• 2005

This paper, introduces a Stochastic Project Scheduling Simulation system (SPSS III) developed by the author to predict a project completion probability in a certain time. The system integrates deterministic CPM, probabilistic PERT, and stochastic Discrete Event Simulation (DES) scheduling methods into one system. It implements automated statistical analysis methods for computing the minimum number of simulation runs, the significance of the difference between independent simulations, and the confidence interval for the mean project duration as well as sensitivity analysis method in What-if analyzer component. The SPSS 111 gives the several benefits to researchers in that it (1) complements PERT and Monte Carlo simulation by using stochastic activity durations via a web based JAVA simulation over the Internet, (2) provides a way to model a project network having different probability distribution functions, (3) implements statistical analyses method which enable to produce a reliable prediction of the probability of completing a project in a specified time, and (4) allows researchers to compare the outcome of CPM, PERT and DES under different variability or skewness in the activity duration data.

• 상하수도학회지
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• 제25권5호
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• pp.751-757
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• 2011

The monitoring technique based on electrical conductivity (EC) can provide researchers with some advantages in maintenance management and is cost-effective as compared with existing CSOs monitoring. In this study, the flow rate estimation using EC data was executed in two sites where storm overflow chamber had installed. In the result of A-site, R2 of second order multinomial between dilution ratio of EC and observed flow rate was showed the range of 0.68 ~ 0.77. And $R^{2}$ of B-site was 0.62 ~ 0.81. On the other hand, cumulative frequency of A-site was 43.4 ~ 52.2% in the relative error level of under 20%. And B-site was 10.1 ~ 46.5%. The flow rate estimation formula was improved through consideration of some parameters including antecedent dry days and rainfall duration. And difference between estimated flow rate and observed flow rate in total rainfall event was very small.

• 한국환경과학회지
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• 제16권7호
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• pp.805-811
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• 2007

The purpose of this study was to invesitigate relationship between rainfall water quality and precipitation characteristic during the accumulated rainfall and rainless period. As the results of the analysis, rainfall water quality was improved in the rainfall duration. Correlation coefficients between rainwater quality and accumulated rainfall were $0.88{\sim}0.99$ except $Cl^-$. and that between rainless period and initial rainfall water quality were $0.62{\sim}0.75$. During the Asian dust event, concentration of the turbidity, BOD and electric conductivity were high. Therefore, it shows that the rainfall water quality is effected by atmospheric conditions before the rainfall events.

• Environmental Engineering Research
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• 제10권2호
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• pp.62-70
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• 2005

Pollution loading of Combined Sewer Overflows (CSOs) is frequently over the capacity of a wastewater treatment plant (WWTP) receiving the water. The objectives of this study are to investigate water quality of CSOs in Anmyun-ueup, Tean province and to apply Storm Water Management Model to predict flow rate and water quality of the CSOs. The capacity of a local WWTP was also estimated according to rainfall duration and intensity. Eleven water quality parameters were analyzed to characterize overflows. SWMM model was applied to predict the flow rate and pollutant load of CSOs during rain event. Overall, profile of the flow and pollutant load predicted by the model well followed the observed data. Based on model prediction and observed data, CSOs frequently occurs in the study area, even with light precipitation or short rainfall duration. Model analysis also indicated that the local WWTP’s capacity was short to cover the CSOs.

• Annals of Clinical Neurophysiology
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• 제3권2호
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• pp.136-142
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• 2001

Background : Nervous system dysfunction is a major complication of end stage renal disease. Although severe neurologic symptoms are partially or completely reversed by adequate hemodialysis, even optimally dialyzed patients will usually not return to normal neurocognitive function. To investigate the influence of chronic renal failure and hemodialysis on higher cognitive function electrophysiologically, we studied auditory P300 event-related potentials in 14 hemodialysis patients and 14 age- and sex-matched normal healthy controls. Methods : The subjects consisted of 14 patients(M: 6, F: 8) with chronic renal failure(CRF) for 1 to 10 years and 14 age- and sex-matched healthy controls(M: 5, F: 9). For the reliability of study, patients with diabetes mellitus, abnormal brain CT findings, or low mini-mental state score(below 20) were excluded. Event related potentials(ERPs) for hemodialysis patients were performed at pre- and post-hemodialysis. To obtain ERPs, subjects underwent 2-tone auditory discrimination test(oddball paradigm). Results : Although the age(control: $48.79{\pm}10.31years$, CRF: $51.21{\pm}7.61years$) and mini-mental state score(control: $27.00{\pm}1.71points$, predialysis CRF: $25.07{\pm}3.58points$) were not different in normal control and CRF groups significantly(P>0.05), P300 latencies at Cz(control: $288.11{\pm}17.36msec$, predialysis CRF: $332.35{\pm}42.34msec$) were significantly delayed(P<0.05)and the duration of Trail making test A was significantly prolonged(control: $64.2{\pm}24.2sec$, CRF: $118.9{\pm}101sec$) in CRF group. P300 latencies between pre- and post-hemodialysis CRF patients(predialysis CRF: $332.35{\pm}42.34msec$, postdialysis CRF: $325.82{\pm}38.69msec$) were not significantly different. The P300 latency was not related with the duration of CRF(Spearman's correlation test, r=0.25, P>0.05) and the frequency of hemodialysis(Spearman's correlation test, r=0.28, P>0.05). Conclusions : From these results, we suggest that P300 latency is valuable in evaluating cognitive brain dysfunction in patients with CRF and hemodialysis does not have a significant effect on cognitive brain dysfunction in patients with CRF.