• ETRI Journal
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• 제39권3호
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• pp.345-352
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• 2017

Traffic management is a highly beneficial mechanism for satisfying quality-of-service requirements and overcoming the resource scarcity problems in networks. This paper introduces an optimal connection admission control mechanism to decrease the packet loss ratio and end-to-end delay in cognitive radio sensor networks (CRSNs). This mechanism admits data flows based on the value of information sent by the sensor nodes, the network state, and the estimated required resources of the data flows. The number of required channels of each data flow is estimated using a proposed formula that is inspired by a graph coloring approach. The proposed admission control mechanism is formulated as a semi-Markov decision process and a linear programming problem is derived to obtain the optimal admission control policy for obtaining the maximum reward. Simulation results demonstrate that the proposed mechanism outperforms a recently proposed admission control mechanism in CRSNs.

• Journal of Information Processing Systems
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• 제11권4호
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• pp.616-629
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• 2015

A mobile terminal will expect a number of handoffs within its call duration. In the event of a mobile call, when a mobile node moves from one cell to another, it should connect to another access point within its range. In case there is a lack of support of its own network, it must changeover to another base station. In the event of moving on to another network, quality of service parameters need to be considered. In our study we have used the Markov decision process approach for a seamless handoff as it gives the optimum results for selecting a network when compared to other multiple attribute decision making processes. We have used the network cost function for selecting the network for handoff and the connection reward function, which is based on the values of the quality of service parameters. We have also examined the constant bit rate and transmission control protocol packet delivery ratio. We used the policy iteration algorithm for determining the optimal policy. Our enhanced handoff algorithm outperforms other previous multiple attribute decision making methods.

• Computers and Concrete
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• 제10권1호
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• pp.19-33
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• 2012

The performance of a concrete is significantly influenced by its mixture proportion and the coating thickness on aggregate surface. The concrete in this study is designed by estimating the blending ratio of aggregate using a densified mixture design algorithm (DMDA) based on an ideal grading curve and estimating the paste volume as the sum of the amount of paste needed to provide an assigned coating paste thickness. So as to obtain appropriate concrete amount, and thus can accurately estimate the property of concrete. Deduction of this mix design formula is simple and easy understanding, and meanwhile to obtain result is fast. This estimation model of mix design is expected to reward to industry and effectively upgrade concrete quality.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.910-917
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• 2020

In fire suppression, continuous delivery of water or foam to the fire source is essential. The present study concerns fire suppression in a ship under sea condition, by introducing reinforcement learning technique to aiming of fire extinguishing nozzle, which works in a ship compartment with six degrees of freedom movement by irregular waves. The physical modeling of the water jet and compartment motion was provided using Unity 3D engine. In the reinforcement learning, the change of the nozzle angle during the scenario was set as the action, while the reward is proportional to the ratio of the water particle delivered to the fire source area. The optimal control of nozzle aiming for continuous delivery of water jet could be derived. Various algorithms of reinforcement learning were tested to select the optimal one, the proximal policy optimization.

• 공학교육연구
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• 제27권1호
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• pp.63-70
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• 2024

The capstone design classes in the College of Engineering are often team project-oriented, and teamwork skills are reported to positively impact problem-solving abilities. While team project courses have various advantages, they also come with challenges such as social loafing and issues related to free riders, which consistently hinder the positive effects of team project courses. To prevent these issues, there is a need to provide a clear evaluation-reward system for team members' contributions. In this study, we examined the reliability of peer evaluation scores for team members' contributions and reviewed methods to incorporate them into team project grades. The review results indicated that peer evaluation scores are deemed to have considerable reliability from a qualitative perspective. However, due to the relatively small team size in team project courses (3 to 6 members per team), using the arithmetic mean of peer evaluation scores is statistically challenging. As a complementary approach, this study proposes limiting the reflection ratio of peer evaluation scores and applying a more macroscopic processing method, not the arithmetic mean, to incorporate peer evaluation scores for team contributions into grades.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8509-8515
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• 2015

본 연구는 소규모 제조업 사업장 남성 근로자들의 직무스트레스와 흡연과의 관련성을 검토할 목적으로 50인 미만의 소규모 제조업 사업장 24개소에 근무하고 있는 남성 근로자 856명을 대상으로 무기명 자기기입식 설문조사를 실시하였다. 연구결과, 조사대상 제조업 남성 근로자의 흡연율은 35.2%이었다. 직무스트레스의 하위영역과 흡연과의 관련성을 검토하기 위한 다변량 로지스틱회귀분석 결과, 직무스트레스 요인 총점과 하위영역(물리적 환경, 직무요구, 조직체계, 보상부적절 및 직장문화)에서의 스트레스요인 점수가 정상군에 비해 고위험 스트레스군에서 현재 흡연군에 속할 위험비가 유의하게 증가하였다. 이 같은 결과는 소규모 제조업 남성 근로자에서의 직무스트레스가 정상인 군보다 고위험스트레스군에서 흡연과의 관련성이 더 높음을 시사하고 있다.

• 생물정신의학
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• 제18권2호
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• pp.101-108
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• 2011

Objectives The aim of this study is to explore the association among DRD4 polymorphism, temperament and alcohol drinking behavior of Koreans in their early adulthood. Method Participants were 172 healthy Korean adults (mean age $28.1{\pm}0.8$). Their temperament was assessed with the Temperament and Character Inventory (TCI) and their alcohol drinking behavior were evaluated with a self-reported questionnaire including the CAGE and the Korean version of Alcohol Use Disorder Identification Test (AUDIT-K). DRD4 exon III 48 base pair variable number of tandem repeats (VNTR) was genotyped by PCR. Results No significant association was found between DRD4 polymorphism and TCI temperament dimension (novelty seeking, harm avoidance, reward dependence, and persistence) as well as alcohol drinking behavior scales. However, novelty seeking was significantly associated with alcohol drinking behavior. The higher level of novelty seeking was associated with the higher severity index of drinking (B = -0.225, p < 0.001) and problematic alcohol use on the CAGE and AUDIT-K [Odds Ratio (OR) = 1.111, 95% Confidence Interval (CI) 1.021-1.209, p = 0.015, OR = 1.087, 95% CI 1.009-1.170, p = 0.028]. Conclusion In our study, while there is no significant association of DRD4 polymorphism with temperament and alcohol drinking behavior, novelty seeking affects problematic alcohol use. Results suggest that novelty seeking may play an important role in problematic alcohol use in young Korean adults.

• 대한불안의학회지
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• 제14권1호
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• pp.7-13
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• 2018

Objective : To determine the association between occupational stress and disordered eating problem in Korean female employees. Methods : We studied 1,452 female employees who attended mental health screenings. Using the Korean Occupational Stress Scale-Short Form (KOSS-SF) and 26-item Korean version of Eating Attitude Test, occupational stress and disordered eating problem were evaluated, respectively. Sociodemographic and clinical characteristics of those with disordered eating problem were examined. Multiple logistic regression analysis was performed to determine which subscale of KOSS-SF was associated with disordered eating problem. Results : Disordered eating problem was associated with interpersonal conflict [odds ratio (OR) 1.882, 95% confidence interval (CI) 1.138-3.112] among various kinds of job stresses. Lack of reward (OR 7.164, 95% CI 1.139-45.043) and insufficient job control (OR 1.953, 95% CI 1.119-3.411) were associated with disordered eating problem in the underweight and normal weight group, respectively. Conclusion : There is an association between occupational stress and disordered eating problem among Korean female employees.

• 산업과 과학
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• 제2권1호
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• pp.21-38
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• 2023

본 논문에서는 주식 시장의 기술적 분석의 기본에 대해 제시하였다. 소매 투자자나 거래자는 다양한 정보원으로부터 나오는 외부 정보를 얻을 수 있는 수단이 제한적이다. 일반적으로 기술적 분석에는 캔들 차트가 주로 활용된다. 인도의 대부분의 브로커는 차트 솔루션도 제공하고 있다. 보안이나 원자재 또는 Forex의 가격 변동을 분석해 보면 일반적인 주가 변동 패턴을 예측 할 수 있다. 주가는 특정 수준에서 반영되며 지지 및 저항 수준으로 널리 알려져 있다. 유가 증권의 가격에 발생하는 모든 일이 과거 언젠가 이미 진행된 패턴 또는 주기의 일부로 간주되기 때문에 이러한 연구는 영리한 애널리스트가 특정 확률로 가격의 미래 변동을 예측하는 데 도움을 줄 수 있다. 캔들스틱의 패턴, 가격 변동, 거래량 및 지표에 대한 연구는 가능한 목표 및 손절매로 높은 확률의 거래를 할 수 있는 기회를 제공한다. 본 연구 결과를 활용하여 트레이더나 투자자는 확률이 높은 거래나 조건을 취하고 투자 손실을 통제할 수 있게 된다.

• Annals of Occupational and Environmental Medicine
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• 제35권
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• pp.33.1-33.9
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• 2023

Background: Studies on the association between occupational stress and depression have been frequently reported. However, the cross-sectional designs of studies limited insight into causal associations. In this study, we investigated the longitudinal association between occupational stress and new-onset depression among employees in a single manufacturing plant. Methods: The annual health checkup data of employees at a manufacturing plant in Korea were collected. A total of 1,837 male employees without depression who completed a health checkup during two consecutive years were included. Occupational stress was measured using a short form of the Korea Occupational Stress Scale (KOSS-SF), and depression was assessed using a Patient Health Questionnaire-2. The association between occupational stress change over the two years and newly developed depression was investigated using two logistic regression models. Results: Across all sub-factors of KOSS-SF, employees who reported increased occupational stress had a higher risk of new-onset depression. Newly developed depression was significantly associated with job demand (odds ratio [OR]: 4.34; 95% confidence interval [CI]: 2.37-7.96), job insecurity (OR: 3.21; 95% CI: 1.89-5.48), occupational climate (OR: 3.18; 95% CI: 1.91-5.31), lack of reward (OR: 2.28; 95% CI: 1.26-4.12), interpersonal conflict (OR: 2.14; 95% CI: 1.18-3.86), insufficient job control (OR: 1.93; 95% CI: 1.05-3.56), and the organizational system (OR: 1.84; 95% CI: 1.01-3.36). Conclusions: For every sub-factor of the KOSS-SF, occupational stress increase and persistent high stress were associated with the risk of developing new-onset depression. Among the seven sub-factors, job demand had the most significant effect. Our results show that occupational stress should be managed to promote employee mental healthcare.