• 산업경영시스템학회지
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• 제40권1호
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• pp.79-86
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• 2017

This research focused on deciding optimal manufacturing WIP (Work-In-Process) limit for a small production system. Reducing WIP leads to stable capacity, better manufacturing flow and decrease inventory. WIP is the one of the important issue, since it can affect manufacturing area, like productivity and line efficiency and bottlenecks in manufacturing process. Several approaches implemented in this research. First, two strategies applied to decide WIP limit. One is roulette wheel selection and the other one is elite strategy. Second, for each strategy, JIT (Just In Time), CONWIP (Constant WIP), Gated Max WIP System and CWIPL (Critical WIP Loops) system applied to find a best material flow mechanism. Therefore, pull control system is preferred to control production line efficiently. In the production line, the WIP limit has been decided based on mathematical models or expert's decision. However, due to the complexity of the process or increase of the variables, it is difficult to obtain optimal WIP limit. To obtain an optimal WIP limit, GA applied in each material control system. When evaluating the performance of the result, fitness function is used by reflecting WIP parameter. Elite strategy showed better performance than roulette wheel selection when evaluating fitness value. Elite strategy reach to the optimal WIP limit faster than roulette wheel selection and generation time is short. For this reason, this study proposes a fast and reliable method for determining the WIP level by applying genetic algorithm to pull system based production process. This research showed that this method could be applied to a more complex production system.

• 산업경영시스템학회지
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• 제39권2호
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• pp.19-27
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• 2016

Maritime transport is now regarded as one of the main contributors to global climate change by virtue of its $CO_2$ emissions. Meanwhile, slow steaming, i.e., slower ship speed, has become a common practice in the maritime industry so as to lower $CO_2$ emissions and reduce bunker fuel consumption. The practice raised various operational decision issues in terms of shipping companies: how much ship speed is, how much to bunker the fuel, and at which port to bunker. In this context, this study addresses an operation problem in a shipping companies, which is the problem of determining the ship speed, bunkering ports, and bunkering amount at the ports over a given ship route to minimize the bunker fuel and ship time costs as well as the carbon tax which is a regulatory measure aiming at reducing $CO_2$ emissions. The ship time cost is included in the problem because slow steaming increases transit times, which implies increased in-transit inventory costs in terms of shippers. We formulate the problem as a nonlinear lot-sizing model and suggest a Lagrangian heuristic to solve the problem. The performance of the heuristic algorithm is evaluated using the data obtained from reliable sources. Although the problem is an operational problem, the heuristic algorithm is used to address various strategic issues facing shipping companies, including the effects of bunker prices, carbon taxes, and ship time costs on the ship speed, bunkering amount and number of bunkering ports. For this, we conduct sensitivity analyses of these factors and finally discuss study findings.

• 대한불안의학회지
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• 제6권2호
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• pp.119-124
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• 2010

Objective : The reliability and validity of the Korean version of the Patient Health Questionnaire-9 (PHQ- 9) was examined in Korean patients with depressive symptoms. Methods : Eighty six outpatients diagnosed as major depressive disorder or depressive episode of bipolar I disorder according to the DSM-IV criteria were assessed with the PHQ-9, Hamilton Depression Rating Scale (HDRS), the Quick Inventory of Depressive Symptomatology Self Report (QIDS-SR), and the Center for Epidemiologic Studies Depression Scale (CES-D). Results : The Cronbach's alpha coefficient from the PHQ-9 was 0.81. And the correlations of each item with the total score were statistically significant (r=0.28-0.70, p<0.01). The test-retest correlation coefficient (r=0.89, p<0.01) was relatively high and correlations of the PHQ-9 with the HDRS, QIDS-SR and CES-D were 0.70, 0.81, and 0.81 respectively. Conclusion : These results demonstrated that the Korean version of PHQ-9 could be a reliable and valid tool for the screening and assessment of depressive patients. The Korean version of PHQ-9 will be a useful tool for screening depressive symptoms in Korea.

• 대한불안의학회지
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• 제11권1호
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• pp.54-60
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• 2015

Objective : To translate Center for Epidemiologic Studies Depression Scale (CES-D) into North Korean language and to examine its reliability and validity Methods : North Korean defectors (n=207) recruited from the call center for North Korean defectors participated. Psychiatrists and psychiatric residents interviewed the participants and made the psychiatric diagnoses. Subsequently, the participants completed the CES-D, Impact of Event-Scale-Revised-North Korea (IES-R-NK), Alcohol Use Disorders Identification Test-North Korea (AUDIT-NK), and Brief Psychological State Inventory for North Korean Refugees (BPSI-NKR) questionnaires. Of the original participants, 143 subjects participated in test-retest reliability study after one week. Results : Cronbach's alpha coefficient of CES-D-NK was superior in both males (0.91) and females (0.93). The test-retest correlation coefficient was high (males, 0.64 ; femals, 0.79). Good convergent validity was evident by significant correlations with IER-R-NK, BPSI-NKR-Depression and BPSI-NKR-PTSD, respectively. CES-D-NK had no or weak correlations with AUDIT-NK and BPSI-NKR-Alcohol, showing its discriminant validity. Conclusion : CES-D-NK could be a reliable and valid tool for screening and assessing depressive symptoms of North Korean defectors.

• 한국측량학회지
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• 제30권3호
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• pp.259-268
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• 2012

본 논문은 Pulsed LiDAR 시스템에 의해 취득된 고밀도 항공 LiDAR 데이터를 이용하여 산림의 이산화탄소 고정량의 객관적이고 과학적인 추정을 목적으로 한다. 이를 위해, 산림지형의 라이다 필터링, 효율적인 개개목 탐지 알고리즘를 통해 취득된 수목의 생장인자를 이용하여 바이오매스 및 이산화탄소 고정량을 추정하는 일련의 방법을 개선하고 통합하여 연구대상지에 적용하였다. 그 결과, 추출된 연구대상지의 DTM은 3.32%의 Type-II 에러를 가진 것으로 나타났고, 개개목 탐지 알고리즘에 의해 식별된 개개목 위치 및 개체수 추정결과는 66.26%의 정확도를 나타냈다. 이와 같은 3차원 산림구조를 이용하여 산출된 연구대상지의 이산화탄소 고정량은 연구대상지의 약 15%에 이르는 면적을 현장조사하여 산출된 이산화탄소 고정량과 비교해 볼 때 약 7.2%의 차이를 나타냈다. 이러한 결과로 미루어 볼 때, 항공 LiDAR 기술이 전통적인 산림조사방법을 대체할 수 있는 가능성을 확인하였다.

• 한국전문물리치료학회지
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• 제16권2호
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• pp.24-30
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• 2009

The purpose of this study was to determine the reliability and validity of the fear-avoidance beliefs questionnaire (FABQ) in assessing Korean patients with low back pain. We performed translation and cross-cultural adaptation of the questionnaire and enrolled 52 patients (18 males and 34 females) with low back pain. The subjects completed a standardized self-administered questionnaire that included the FABQ assessment along with evaluations for the visual analogue scale (VAS), Oswestry disability index (ODI), self-rating anxiety scale (SAS), and Beck depression inventory-Korean version (K-BDI). The reliability of the obtained data was determined by evaluating the internal consistency on the basis of the intraclass correlation coefficient (ICC) and the Cronbach's alpha values, while the validity of the data was examined by correlating the FABQ scores to the VAS, ODI, SAS, and K-BDI scores. The translated versions of the FABQ showed good test-retest reliability: ICC (3, 1)=.90 (FABQ for physical activity) and .97 (FABQ for work) these values were statistically significant (p<.01). The Cronbach's alpha value for FABQ was .90 (p<.01). FABQ moderately correlated with pain, disability, anxiety, and depression (p<.01). The results of this study indicate that the Korean version of the FABQ is a reliable and valid instrument for measuring fear-avoidance beliefs in Korean patients with low back pain.

• Child Health Nursing Research
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• 제18권2호
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• pp.53-59
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• 2012

Purpose: This study was done to verify the reliability and validity of the Korean version of DMCI in Korean adolescents. Methods: A methodological study design was used with Cronbach's ${\alpha}$ for reliability, and an exploratory factor analysis and contrasted groups approach for construct validity. DMCI was translated into Korean and tested with a sample of 406 adolescents in Korea. The data were analyzed using Cronbach's ${\alpha}$, item correlation with total, principal component factor analysis, and t-test. Results: The translated content of the DMCI was validated by nursing faculty members and translation equivalency was obtained. The Cronbach's ${\alpha}$ of the DMCI simplified with 18 items was .78. The factor analysis revealed three factors explaining 41.5% of total variance and the corresponding factors were self-observation (21.6%), self-judgement (11.4%), and self-confidence (8.6%). The mean score for the DMCI in the aggression group was significantly lower than the non-aggression group. Conclusion: Results of this study suggest that the Korean version of DMCI can used as a reliable and valid measure to assess decision making competency in Korean adolescents.

• 한국과학교육학회지
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• 제4권2호
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• pp.57-63
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• 1984

An inquiry approach in teaching science has been advocated by many science educators for the past few decades, and most elementary and secondary science curricula have incorporated it in varying degrees. It has been proven in recent studies, however, that there exists considerable discrepancy between the expectation of outcomes of the inquiry approach and the actuality. This in part implies that there is a somewhat urgent need for the systematic evaluation of the approach in teaching science. The purpose of this study is to develop a comprehensive instrument for evaluating inquiry teaching approaches embedded in science curricular materials. To develop a more valid and reliable instrument a set of empirical data was used in the developmental procedure, and most of the previous studies regarding inquiry teaching method and inquiry evaluation were consulted. The inquiry evaluation method developed in this study, called the Scientific Inquiry Evaluation Inventory (SIEI), is composed of three parts: (1) analyzing and coding each science process task of inquiry activity; (2) evaluating each inquiry activity as a whole; and (3) evaluating each science laboratory curriculum as a whole. The first part of the instrument consists of twenty science process categories and thirty subcategories grouped into four sections: (1) gathering and organizing data; (2) interpreting and analyzing data; (3) synthesizing results and evaluation; and (4) hypothesizing and designing an experiment. The science process categories are arranged according to the level of difficulty, psychological level of thinking, degree of creativity demand, and the model of the process of scientific inquiry, which is also developed in the study. The second part of the instrument contains four evaluation scales of inquiry activity: (1) competition/cooperation scale; (2) discussion scale; (3) openness scale; and (4) inquiry scope scale. And the last part consists of three methods for evaluating a science laboratory curriculum as a whole: (1) inquiry pyramid; (2) inquiry index; and (3) difficulty index. The instrument is designed to be used by teachers, science curriculum developers and science education evaluators for the purpose of diagnosing the nature and appropriateness of scientific inquiry introduced in secondary science curricular materials, especailly in laboratory work and field work.

• The Korean Journal of Pain
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• 제33권3호
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• pp.226-233
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• 2020

Background: We aimed to compare interlaminar epidural steroid injections (ILESI) and bilateral transforaminal epidural steroid injections (TFESI) on pain intensity, functional status, depression, walking distance, and the neuropathic component in patients with lumbar central spinal stenosis (LCSS). Methods: The patients were divided into either the ILESI or the bilateral TFESI groups. Prime outcome measures include the numerical rating scale (NRS), Oswestry disability index (ODI), Beck depression inventory (BDI), and pain-free walking distance. The douleur neuropathique en 4 questions score was used as a secondary outcome measure. Results: A total of 72 patients were finally included. NRS, ODI, and BDI scores showed a significant decline in both groups in all follow-ups. Third-month NRS scores were significantly lower in the ILESI group (P = 0.047). The percentages of decrease in the ODI and BDI scores between the baseline and the third week and third month were significantly higher in the ILESI group (P = 0.017, P = 0.001 and P = 0.048, P = 0.030, respectively). Pain-free walking distance percentages from the baseline to the third week and third month were significantly higher in the ILESI group (P = 0.036, P < 0.001). The proportion of patients with neuropathic pain in the bilateral TFESI group significantly decreased in the third week compared to the baseline (P = 0.020). Conclusions: Both ILESI and TFESI are reliable treatment options for LCSS. ILESI might be preferred because of easier application and more effectiveness. However, TFESI might be a better option in patients with more prominent neuropathic pain.

• 대한불안의학회지
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• 제7권1호
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• pp.9-15
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• 2011

Objectives : We examined the reliability and validity of the Korean version of the Depression and Somatic Symptom Scale (DSSS) in Korean patients with depressive symptoms. Methods : Participants were 55 outpatients diagnosed with major depressive disorder, a depressive episode of bipolar I disorder, somatoform disorder, panic disorder, generalized anxiety disorder, or post-traumatic stress disorder according to the DSM-IV criteria. We assessed them using the Korean versions of the DSSS, Hamilton Depression Rating Scale (HDRS), and Quick Inventory of Depressive Symptomatology Self Report (QIDS-SR). Results : The Korean version DSSS had a Cronbach's alpha of 0.90. Moreover, each item's correlation with the total score was statistically significant (r=0.24-0.71, p<0.01). The test-retest correlation coefficient (r=0.83, p<0.01) was relatively high, and the DSSS correlations with the HDRS and QIDS-SR were 0.77 and 0.74, respectively. Conclusion : These results demonstrate that the Korean version of the DSSS could be a reliable and valid tool for screening and assessing depressive patients. The Korean version of the DSSS will be a useful tool for screening both depressive and somatic symptoms in Korea.