• 대기
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• 제24권3호
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• pp.391-402
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• 2014

This study investigated the performances of precipitable water vapor (PWV) retrieval from the sets of ground global positioning system (GPS) signals, each of which had different length of observing-session duration, for the purpose of obtaining as short session duration as possible that is required at the least for appropriate retrieval of the PWV for meteorological usage. The shorter duration is highly desirable to make the most use of the GPS instrument on board the mobile observation vehicle making measurements place by place. First, using Bernese 5.0 software the PWV retrieval was conducted with the data sets of GPS signals archived continuously in 30 seconds interval during 2-month period of January and February, 2012 at Bukgangneung site. Each of the PWVs produced independently using different session durations was compared to that of radio-sonde launched at the same GPS location, a Bukgangneung site. Second, the same procedure was done using the data sets obtained from the mobile observation vehicle that was operating at Boseong area in Jeonnam province during Changma observation campaign in 2013, and the results were compared to that at Bukgangneung site. The results showed that as the observing-session duration increased the retrieval errors decreased with the dramatic change happening between 3 and 4 hours of the duration. On average, the root mean square error (RMSE) of the retrieved PWV was around 1 mm for the durations of greater than 4 hours. The results at both the Bukgangneung (fixed site) and Boseong (mobile vehicle) seemed to be fairly comparable with each other. From this study it is believed that at least 4 hours of observing-session duration is needed for the retrieval of PWV from the ground GPS for meteorological usage using Bernese 5.0 software.

• 한국구조물진단유지관리공학회 논문집
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• 제5권1호
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• pp.176-187
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• 2001

Most bridges have expansion joints to accommodate thermal expansion and contraction without inducing large forces in the bridges. To evaluate the effects of earthquake-induced at expansion joints of concrete bridges, the first part of this paper deals with a collinear impact between concrete segments, which have the same cross section but different lengths. Especially, impact force, momentum, strain energy and kinetic energy are formulated in mathematically. These results are then used in the second part of this paper to simulate a realistic yet simple analysis of seismic pounding in concrete bridges. Analysis of seismic pounding in idealized concrete bridges is carried out by using a simple lumped-mass model and rationally determined values of the coefficient of restitution and the duration of impact.

• Structural Engineering and Mechanics
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• 제9권1호
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• pp.69-88
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• 2000

A relatively simple model of a buried structure response to a surface loading that can simulate a possible opening and closure of a gap between the soil and the structure is presented. Analysis of the response of small and medium scale buried roof slabs under surface impulsive loading shows that the model's predictions are in fairly good agreement with the experimental results. Application of the model to a study case shows the relative influence of system parameters such as, the depth of burial, the arching coefficient, and the roof thickness, on the interface pressure and on the roof displacement. This model demonstrates the effect of a gap between the structure and the soil. The relative importance of including a gap opening and closure in the analysis is examined by the application of the model to a study case. This study results show that the deeper the depth of burial, the longer the gap duration, and the shorter the duration of the initial interface impact, while the higher the soil's shear resistance, the higher the gap duration, and the shorter the initial interface impact duration.

• Communications for Statistical Applications and Methods
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• 제16권1호
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• pp.21-29
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• 2009

Engle과 Russell (1998)의 ACD 모형은 재무학에서 가격과 거래 시간의 밀접한 관계에 대한 관심을 불러 일으켰다. ACD 모형은 GARCH 모형과의 유사성을 바탕으로 Box-Cox 변환과 충격 함수 곡선(shocks impact curve)을 적용시켜 Log ACD, Power ACD, Box-Cox ACD 등과 같은 보다 유연한 모형으로 일반화될 수 있다. 본 연구에서는 이와 같이 일반화된 ACD 모형들을 국내 주식시장에서 거래되고 있는 주식의 price duration에 적용시켜 그 성능을 비교해보고자 한다.

• International Journal of Industrial Entomology and Biomaterials
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• 제16권1호
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• pp.1-5
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• 2008

The present study was carried out with the aim to evaluate the viability of layings (delivery of fertilized and unfertilized eggs) with egg laying duration of elite bivoltine races. The temporal aspect of mating in terms of egg layings duration may also have impact on the number of eggs laid, pattern of egg laying and their viability. After different interval of egg laying duration, moth of Bombyx mori are removed from oviposition site after they have completed egg laying. Present investigation confirmed that there are no significant difference in relation to the occurrence of viable (fertilized) and non viable (unfertilized) eggs and duration of oviposition. Percentage of unfertilized eggs varied from 2.41 to 3.42% in case of CSR-3, 2.59 to 3.62% in case of CSR-6, 2.82 to 3.66% in case of CSR-16 and 2.58 to 3.40% in case of CSR-17 in different treatments. The occurrence of unfertilized eggs are also not significant in the different treatments specially in those eggs which were laid 24 hours after oviposition and kept for 4 months hibernation schedule.

• Journal of Nutrition and Health
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• 제40권6호
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• pp.509-516
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• 2007

The purpose of this study was to investigate the impact DM duration on cardiovascular disease risk factors in Korean Type 2 diabetes mellitus patients. The subject were 250 (male: 134, female: 118) Korean Type 2 DM patients recruited from a general hospital's DM clinic. Anthropometric and hematological variables and dietary intake were assessed. The subject's mean age was 60.2 years and duration of diabetes was 9.5 years. As far as DM duration was concerned, male subjects with long duration (${\geq}$ 5 years and longer) showed significantly lower weight, fat free mass, skeletal muscle mass, BMI (p < 0.05) and higher 2hrs-postprandial plasma glucose (p < 0.05) and concentration of Hemoglobin A1c (p < 0.01) compared to those with less 5years of duration. In female subjects, same trend was found. Female subjects with long duration (${\geq}$ 5 years and longer) showed significantly higher fat free mass (p < 0.05) and skeletal muscle mass (p < 0.05), Hemoglobin A1c (p < 0.01), HDL-cholesterol (p < 0.01) and triglyceride (p < 0.05), dietary intakes of protein (p < 0.05) and fat (p < 0.05) compared to those with less 5years of duration. In conclusion, Type II DM patients of long duration had higher blood lipid concentrations and higher carbohydrates intakes. Subjects followed diet prescription strictly showed lower blood lipid concentration, suggesting the effectiveness of diet to manage Type 2 DM patients.

• 환경영향평가
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• 제20권1호
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• pp.71-78
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• 2011

This paper aims to assessing impact of reduction of non-point source pollution in the Bokha Stream watershed. The BASINS/HSPF model was calibrated and verified for water flow and water qualities using Total Maximum Daily Load 8days data from 2006 to 2007. Accuracy of the BASINS/HSPF models in simulating hydrology and water quality was compared and there were somewhat differences of statistical results, but water flow and water quality were simulated in good conditions over the study period. The applicability of models was tested to evaluate non-point source control scenarios to response hydrology and water quality in the Bokha stream using various measures which include BMPs approach and change of landuse. The evaluation of reduction of non-point source pollution was developed using load-duration curve. Despite strong reduction of non-point source, there are not satiated target quality at low flow season.

• 전산구조공학
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• 제9권3호
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• pp.187-197
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• 1996

Explicit 직접적분법 알고리듬을 사용하여 Euler기둥의 동적 좌굴거동을 해석할 수 있는 수치해석법을 제시하였다. 평면뼈대 유한요소를 기하학적 비선형 거동과 전체좌굴의 영향을 고려할 수 있도록 보의 대변위 이론으로부터 유도하였고, central difference method를 바탕으로 해석 알고리듬을 개발하였다. 다양한 형상, 크기, 재하시간을 갖는 충격하중에 대하여 Euler기둥의 동적좌굴거동과 고유치 문제를 해석하였다. 수치해석 예제를 통하여 본 연구의 결과를 검증하였다.

• 노동경제논집
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• 제40권2호
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• pp.69-87
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• 2017

본 연구는 "한국교육고용패널" 조사를 이용하여 학자금 대출이 대졸자 직업탐색 기간에 미치는 영향에 대해 추정하였다. 특히 학자금 대출이 그 유형에 따라 대출의 보유자에게 상이한 영향을 미칠 가능성을 고려하였다. 추정 결과에 따르면, 첫째, 학자금 보증 대출의 경우 비대출자에 비해 상대적으로 더 긴 직업탐색 기간을 갖는 것으로 나타났으며, 이는 원리금 상환을 고려하여 더 높은 임금을 제안받기 위한 선택일 개연성이 있다고 사료된다. 둘째, 취업 후 상환 학자금 대출의 경우 비대출자에 비해 상대적으로 더 짧은 직업탐색 기간을 소비할 뿐만 아니라 역시 더 낮은 임금을 받는 것으로 나타났다. 이와 같은 사실은 이 대출의 보유자가 취업 시까지 납부할 이자는 유예되지만, 축적되는 이자 부담과 여타 학자금 대출 제도에 비해 상환 계획이 짧다는 점 등에 부담을 느끼는 심리적 부담에 의한 역기능이 발생한다고 해석할 수 있다.

• 소음진동
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• 제1권2호
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• pp.115-120
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• 1991

The impact hammer is extensively used in experimental modal analysis as a means to provide force over a broad range of frequencies. The hammer mass and the impact head are often changed to achieve a desired impact time duration with its corresponding input frequency spectrum, these mass changes affect the performance and sensitivity of the force transducer employed to measure the impact force. Both a mathematical model describing the effects of impact head and hammer mass on the performance of the force transducer and experimental verification of this model are presented here.