• 한국농공학회논문집
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• 제58권5호
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• pp.81-90
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• 2016

Due to droughts and water shortages causing severe damage to crops and other vegetations, much attention has been given to efficient irrigation for upland farming. However, little information has been known to measure soil moisture levels in a field scale and apply their spatial variability for proper irrigation scheduling. This study aimed to characterize the spatial variability and temporal stability of soil water contents at depths of 10 cm, 20 cm and 30 cm on flat (loamy soil) and hill-slope fields (silt-loamy soil). Field monitoring of soil moisture contents was used for variogram analysis using GS+ software. Kriging produced from the structural parameters of variogram was applied for the means of spatial prediction. The overall results showed that the surface soil moisture presented a strong spatial dependence at the sampling time and space in the field scale. The coefficient variation (CV) of soil moisture was within 7.0~31.3 % in a flat field and 8.3~39.4 % in a hill-slope field, which was noticeable in the dry season rather than the rainy season. The drought assessment analysis showed that only one day (Dec. 21st) was determined as dry (20.4 % and 24.5 % for flat and hill-slope fields, respectively). In contrary to a hill-slope field where the full irrigation was necessary, the centralized irrigation scheme was appeared to be more effective for a flat field based on the spatial variability of soil moisture contents. The findings of this study clearly showed that the geostatistical analysis of soil moisture contents greatly contributes to proper irrigation scheduling for water-efficient irrigation with maximal crop productivity and environmental benefits.

• International Journal of Railway
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• 제6권2호
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• pp.33-44
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• 2013

In recent years, energy consumption in the transportation sector by expanding motorization continues to increase in almost every country in the world. Moreover, the growth rate of the transportation energy consumption is significantly higher than those of the civilian and industrial sectors. Therefore, every country strives to reduce its dependence on private transport, which is the main contributor to the transportation energy consumption. In many countries, concepts such as Transit Oriented Development (TOD) or New Urbanism, which controls road traffic by increasing the proportion of the public transportation significantly, have been implemented to encourage a modal shift to public transport. However, the level of change required for eliminating environmental problems is a challenging task. Minimizing transportation energy consumption by controlling the increase of the traffic demand and maintaining the level of urban mobility simultaneously is a pressing dilemma for each city. Grasping the impact of the diversity of the urban transport and infrastructure is very important to improve transportation energy efficiency. However, the potential for reducing urban transportation energy consumption has often been ineffectively demonstrated by the diversity of cities. Therefore, the accuracy of evaluating the current efficiency rate of the urban energy consumption is necessary. Nevertheless, quantitative analyses related to the efficiency of transportation energy consumption are scarce, and the research on the current condition of consumption efficiency based on international quantitative analysis is almost nonexistent. On the basis of this background problem definitions, this research first built a database of the transportation energy consumption of private modes in 119 cities, with an attempt to reflect individual travel behaviors calculated by Person Trip data. Subsequently, Data Envelopment Analysis (DEA) was used as an assessment method to evaluate the efficiency of transportation energy consumption by considering the diversity of the urban traffic features in the world cities. Finally, we clarified the current condition of consumption efficiency by attempting to propose a target values for improving transportation energy consumption.

• 한국안전학회지
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• 제29권4호
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• pp.116-122
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• 2014

This study proposes a system reliability analysis of rack storage facilities subjected to forklift colliding events. The proposed system reliability analysis consists of two steps: the first step is to identify dominant failure modes that most contribute to the failure of the whole rack facilities, and the second step is to evaluate the system failure probability. In the first step, dominant failure modes are identified by using a simulation-based selective searching technique where the contribution of a failure mode to the system failure is roughly estimated based on the distance from the origin in the space of the random variables. In the second step, the multi-scale system reliability method is used to compute the system reliability where the first-order reliability method (FORM) is initially used to evaluate the component failure probability (failure probability of one member), and then the probabilities of the identified failure modes and their statistical dependence are evaluated, which is called as the lower-scale reliability analysis. Since the system failure probability is comprised of the probabilities of the failure modes, a higher-scale reliability analysis is performed again based on the results of the lower-scale analyses, and the system failure probability is finally evaluated. The illustrative example demonstrates the results of the system reliability analysis of the rack storage facilities subjected to forklift impact loadings. The numerical efficiency and accuracy of the approach are compared with the Monte Carlo simulations. The results show that the proposed two-step approach is able to provide accurate reliability assessment as well as significant saving of computational time. The results of the identified failure modes additionally let us know the most-critical members and their failure sequence under the complicated configuration of the member connections.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.223.1-223.1
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• 2013

Since sapphire single crystal is one of the materials that have excellent mechanical and optical properties, the single crystal is widely used in various fields, and the demand for the use of substrate of LED devices is increasing rapidly. However, crystal defects such as dislocations and stacking faults worsen the properties of the single crystal intensely. When sapphire wafer of single crystal is used as LED substrate, especially, crystal defects have a strong influence on the characteristics of a film deposited on the wafer. In such a case quantitative assessment of the defects is essential, and the evaluation technique is now becoming one of the most important factors in commercialization of sapphire wafer. Wet etching is comparatively easy and accurate method to estimate dislocation density of single crystal because etching reaction primarily takes place where dislocations reached crystal surface which are chemically weak points, and produces etch pit. In the present study, the formation behavior of etch pits and etching time dependence were studied systematically. Etch pit density(EPD) analysis using optical microscope was also conducted and measurement uncertainty of EPD was studied to confirm the reliability of the results. EPDs and measurement uncertainties for 4 inch sapphire wafers were analyzed in terms of 5 and 21 points EPD readings. EPDs and measurement uncertainties in terms of 5 points readings for 4 inch wafers were compared by 2 organizations. We found that the average EPD value in terms of 5 points readings for a 4 inch sapphire wafer may represent the EPD value of the wafer.

• Laboraroty Animal Research
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• 제34권4호
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• pp.185-194
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• 2018

The different polymorphisms of the transcription factor 7-like 2 (TCF7L2) gene promote variances in diabetes susceptibility in humans. We investigated whether these genotypes also promote differences in diabetic susceptibility in commercial pigs. Growing pigs (Landrace, both sex, 50-60 kg) with the C/C (n=4) and T/T (n=5) TCF7L2 genotypes were identified and intravenously injected with streptozotocin (STZ, 40 mg/kg) twice in weekly intervals, then a high-energy diet was offered. Oral glucose tolerance tests, blood analyses and the homeostasis model assessment-insulin resistance (HOMA-IR) index calculations were performed. The animals were sacrificed at the end of 12 weeks of treatment to reveal the pancreas histomorphometry. The results showed that all of the treated pigs grew normally despite exhibiting hyperglycemia at two weeks after the induction. The glycemic level of the fasting or postprandial pigs gradually returned to normal. The fasting insulin concentration was significantly decreased for the T/T carriers but not for the C/C carriers, and the resulting HOMA-IR index was significantly increased for the C/C genotype, indicating that the models of insulin dependence and resistance were respectively developed by T/T and C/C carriers. The histopathological results illustrated a significant reduction in the pancreas mass and insulin active sites, which suggested increased damage. The results obtained here could not be compared with previous studies because the TCF7L2 background has not been reported. Growing pigs may be an excellent model for diabetic in children if the animals are genetically pre-selected.

• 한국콘텐츠학회논문지
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• 제22권6호
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• pp.596-605
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• 2022

본 연구는 강요된 빚 피해 및 개입방안에 관한 미국의 가정폭력 연구의 성과를 소개하였다. 강요된 빚의 이론과 개념, 피해 경험과 영향, 개입에 관한 미국의 선행연구를 검토한 결과는 다음과 같다. 첫째, 강요된 빚은 강압적 통제로서의 가정폭력과 통제 메커니즘으로서의 경제적 폭력을 이론적 기반으로 사기 거래와 강제거래를 포함하는 가해자의 폭력 전술로 정의되었다. 둘째, 가정폭력 피해자 중 강요된 빚 경험자는 절반 이상으로 나타났으며, 그 영향은 신용 훼손과 경제적 의존, 주택·고용·안전과 관련한 장벽이었다. 셋째, 강요된 빚 피해에 개입하기 위해 장시간의 회복 기간과 불확실성을 견디고, 집중적·개별적 옹호를 제공하며, 피해자 구제를 위한 정책과 단일한 절차가 부재하다는 문제를 극복해야 할 것이다. 또한, 강요된 빚에 대한 사정 및 서비스 연계를 위하여 서비스 제공자에 대한 교육과 훈련이 필요하며, 강요된 빚 피해자의 역량을 강화하고 안전을 최우선으로 고려하는 방향으로 서비스가 제공되어야 할 것이다.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1991-1999
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• 2021

The response changes of the specific growth rate of Lemna minor duckweed was modeled using the logarithms of frond numbers on tritium activity concentration and gamma radiation dose from cobalt 60. The concept of average specific growth rate depends on the general exponential growth pattern, where toxicity is estimated based on the effect on the growth rate. One of the main questions of the effect of the radiation dose on duckweed is how to correlate the effect of beta radiation with the effect of any other radiation for modeling radiation on Lemna minor. Experimental data were extrapolated by utilizing the OECD guidelines. A linear relationship of absorbed dose and activity concentration was obtained for the average dependency growth rate of Lemna minor as D = (0.1257)·A^0.585. The dose rate of gamma irradiation from ⁶⁰Co increases with tritium activity dependence, on the specific growth rate of the Lemna minor duckweed. An increase in the tritium activity causes a decrease in the specific growth rate of the Lemna minor duckweed. It indicates that as the quantity of the beta radiation dose increase in Lemna minor duckweed, a higher quantity of gamma radiation will be required to cause the same effect in the specific growth rate of Lemna minor duckweed. The relation between the inhibition of the Lemna minor seedling growth and gamma and beta radiation dosage agrees roughly with that between the decrease of survival rate or fertility and dosage.

• 한국전문물리치료학회지
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• 제30권1호
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• pp.32-40
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• 2023

Background: Equating is a statistical procedure used to create a common measurement scale across two instruments. Item-level information should be taken into consideration so that scores can communicate interchangeably across the instruments. Objects: To investigate a common measurement scale across two health-related quality of life questionnaires (HRQOL) applied to various cancer survivors who underwent palliative care in healthcare institutions. Methods: A total of 139 cancer survivors who underwent palliative care were recruited from two rehabilitation hospitals and an oriental medicine hospital. Participants consisted of various cancer survivors who presented to the sites for palliative care. They were asked to fill out Korean versions of the World Health Organization Quality of Life (WHOQOL-BREF) and EuroQOL-5 dimension (EQ-5D) questionnaires following the palliative care. For the item level comparison, the Rasch rating scale model was used to investigate how participants regarded individual test items of two instruments in relation to item difficulty calibrations. Results: All items except the three items fit the Rasch model. One item (anxiety/depression) of the EQ-5D and two items (dependence on medical aids and negative feelings) of the WHOQOL-BREF are misfit. The WHOQOL-BREF targets the survivors well, while the EQ-5D is able to target the survivors with lower HRQOL levels with some ceiling effects. By inspecting the item difficulty calibrations of the two instruments, five items of the WHOQOL-BREF are selected as common items in relation to the EQ-5D. These five items are considered compatible with each other. Differential item functioning (DIF) analysis reveals that the healthcare item of the WHOQOL-BREF vs the self-care item of the EQ-5D exhibits significant DIF. Conclusion: Findings suggest that one paired item should be taken into consideration when equating the WHOQOL-BREF and the EQ-5D applied to cancer survivors who underwent palliative care.

• 생물정신의학
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• 제14권4호
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• pp.249-255
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• 2007

목 적: 본 연구에서는 알코올 의존의 재발 예측 인자로 중요하다고 알려진 사회 인구학적 변인, 음주력, 음주갈망, 치료 동기, 병식과 같은 요인들 중에 어떤 요인들이 한국인 알코올 의존의 재발을 예측하는지를 전향적으로 조사하였다. 방 법: 알코올 의존 환자 48명을 대상으로 사회 인구학적 특성, 음주력, Timeline Follow-Back(TLFB), Obsessive-Compulsive Drinking Scale(OCDS), Alcohol Urge Questionnaire(AUQ), Pennsylvania Alcohol Craving Scale(PACS), University of Rhode Island Change Assessment(URICA), Hanil Alcohol Insight Scale(HAIS)등을 조사한 후, 24주간 총 11회에 걸쳐 외래를 방문하도록 하였다. 24주 동안 조사한 TLFB자료에 근거하여 대상자 중에서 과음(일일 5standard drinking 이상)일이 나타난 경우 혹은 더 이상 추적 방문이 되지 않은 경우 모두 재발한 것으로 하여 재발군으로 분류하였으며, 그렇지 않은 경우를 비재발군으로 분류하였다. 알코올 의존의 재발을 예측할 수 있는 요인을 찾는 방법으로 SPSS PC+11.5 프로그램의 로지스틱 회귀분석을 이용하였다. 결 과: 음주를 시작한 연령, 음주로 인한 문제가 발생된 연령, 최근 1년간 1일 음주량, 최근 1년간 월 음주일수, PACS, AUQ, OCDS, URICA, HAIS와 같은 요인들 중 최근 1년간 1일 음주량과 HAIS 점수가 알코올 의존의 재발에 영향을 주는 것으로 나타났다(p<.05). 결 론: 알코올 의존 환자의 치료에서 1일 음주량이 많은 경우와 병식이 낮은 경우가 재발 가능성이 높으므로 앞으로의 치료에서 이러한 요인을 고려해야 할 것이다.

• 한국전산구조공학회논문집
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• 제33권2호
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• pp.129-136
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• 2020

본 연구에서 기기 지진취약도 정보의 부분 종속 관계를 정확하게 고려할 수 있는 샘플링 기반 지진 확률론적 리스크 평가 정량화 기법을 개발하였다. 구체적으로 두 가지 대표적 방법론인 EPRI 지진취약도 입력기반 정량화 방법과 JAERI 지진취약도 입력기반 정량화 기법의 장점을 결합하여 리스크 정량화 방법를 제안하였다. 본 연구에서 제안하는 방법의 가장 중요한 특징은 EPRI 지진취약도 입력을 JAERI 지진취약도 입력 공간으로 치환하여 샘플링 방법으로 SPRA 수행하는 것에 있다. 제안된 샘플링기반 접근법을 간단한 예제부터 실제 원전의 지진 확률론적 리스크 평가 문제에 적용한 결과, 본 연구에서 제안하는 방법이 정해에 가까운 시스템 지진취약도 및 지진리스크 값을 산출함을 확인할 수 있었다. 그러므로 본 연구에서 제안하는 방법론은 기존의 SPRA 정량화 방법이 다룰 수 없는 시스템 내 부분 종속 조건을 고려하여 지진 리스크를 정확하게 평가할 수 있는 유용한 도구로 활용될 수 있을 것이라 기대한다.