• Journal of applied mathematics & informatics
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• 제26권5_6호
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• pp.889-900
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• 2008

The problem of scheduling n jobs on a single machine is considered when the machine is subject to stochastic breakdowns. The objective is to minimize the weighted squared deviation of job completion times from a common due date. Two versions of the problem are addressed. In the first one the common due date is a given constant, whereas in the second one the common due date is a decision variable. In each case, a general form of deterministic equivalent of the stochastic scheduling problem is obtained when the counting process N(t) related to the machine uptimes is a Poisson process. It is proved that an optimal schedule must be V-shaped in terms of weighted processing time when the agreeable weight condition is satisfied. Based on the V-shape property, two dynamic programming algorithms are proposed to solve both versions of the problem.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2012년도 추계학술발표대회
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• pp.1441-1444
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• 2012

SW 기업들이 SW 프로세스 개선(Software Process Improvement; SPI)을 개선하기 위해 많은 관심과 노력을 투입해 왔음에도 불구하고, 이런 SW 프로세스 개선 활동이 품질, 비용, 납기준수에 어떠한 영향을 주는지에 대한 구체적인 자료들이 부족한 편이다. 본 연구에서는 SW 프로세스 개선활동들에 대한 이해의 폭을 넓히기 위해 국내 SW 개발 조직의 프로젝트 관리자를 대상으로 SW 프로세스의 공학수준과 DICE 수준관련 자료를 수집하였다. 이를 기반으로 SW 프로세스 개선 모델이 제시하고 있는 가정사항인 SW 프로세스 능력수준이 높으면 프로젝트 성과가 좋은지와 조직변화의 성공요인을 제시하는 DICE 수준에 따라 납기 성과의 변화를 살펴보았다. 분석결과 SW공학수준과 DICE 수준이 높을수록 납기가 줄어드는 것으로 나타났다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.102-114
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• 2021

Biofouling represents an important problem in the shipping industry since it causes the increase in surface roughness. The most of ships in the current world fleet do not have good coating condition which represents an important problem due to strict rules regarding ship energy efficiency. Therefore, the importance of the control and management of the hull and propeller fouling is highlighted by the International Maritime Organization and the maintenance schedule optimization became valuable energy saving measure. For adequate implementation of this measure, the accurate prediction of the effects of biofouling on the hydrodynamic characteristics is required. Although computational fluid dynamics approach, based on the modified wall function approach, has imposed itself as one of the most promising tools for this prediction, it requires significant computational time. However, during the maintenance schedule optimization, it is important to rapidly predict the effect of biofouling on the ship hydrodynamic performance. In this paper, the effect of biofilm on the ship hydrodynamic performance is studied using the proposed performance prediction method for three merchant ships. The applicability of this method in the assessment of the effect of biofilm on the ship hydrodynamic performance is demonstrated by comparison of the obtained results using the proposed performance prediction method and computational fluid dynamics approach. The comparison has shown that the highest relative deviation is lower than 4.2% for all propulsion characteristics, lower than 1.5% for propeller rotation rate and lower than 5.2% for delivered power. Thus, a practical tool for the estimation of the effect of biofouling with lower fouling severity on the ship hydrodynamic performance is developed.

• Journal of the Korean Wood Science and Technology
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• 제14권1호
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• pp.45-54
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• 1986

A study was conducted to determine the physical properties related to drying characteristics, the seasonal air drying curves and the kiln drying schedule for taun lumber imported and utilized. This kiln drying schedule was found by oven drying and developed by pilot testing of green lumber and partially air dried lumber. The results of this study were as follows; 1. Average green specific gravity and standard deviation of heartwood lumber were 0.60${\pm}$0.03 and those of sapwood lumber were 0.64${\pm}$0.02. 2. Radial shrinkage from green to air dry and from green to oven dry were 3.05 percent and 5.96 percent respectively, and tangential shrinkage from green to air dry and to oven dry were 5.49 percent and 8.74 percent respectively. 3. Drying time for 25mm thick green lumber (50 percent moisture content) air dried to 30 percent moisture content were 14 days in springtime. 6 days in summertime, and 12 days in autumntime, whereas for 50mm thick lumber in 36 days in springtime, 18 days in summertime, 38 days in autumntime. 4. Kiln drying schedules developed by oven drying were T8-B3 for 25mm thick lumber and T5-B2 for 50mm thick lumber. 5. Kiln drying curves of green 25mm and 50mm thick lumber were similar to those of partially air dried lumber from the level of 30 percent average moisture content. Green 25mm thick lumber (55.7 percent moisture content) was dried to 9.3 percent moisture content in 101.5 hours and green 50mm thick lumber (65.6 percent moisture content) was dried to 11.5 percent moisture content in 526 hours. 6. End checking for green 25mm thick lumber occured in 49.6 percent moisture content and reached maximum amount in 27.6 percent moisture content and closed in 15.8 percent moisture content. 7. End checking for green 50mm thick lumber and partially air dried lumber developed and reached maximum amount earlier then for 25mm thick lumber. 8. Final moisture content of surface layer for 50mm thick lumber was one half of that of core, and moisture content equalized in the lumber after nine days of room conditioning. 9. Casehardening for 50mm thick lumber was slight and was conditioned after nine days of room stroage. 10. Drying defects, such as end checking and surface checking, were not observed and the quality of dry lumber was first.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.601-611
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• 2017

This paper proposes a simultaneous control of frequency deviation and electric vehicles (EVs) battery state of charge (SOC) using load frequency control (LFC) and EV controllers. In order to provide both frequency stabilization and SOC schedule near optimal performance within the whole operating regions, a multiple-input multiple-output model predictive control (MIMO-MPC) is employed for the coordination of LFC and EV controllers. The MIMO-MPC is an effective model-based prediction which calculates future control signals by an optimization of quadratic programming based on the plant model, past manipulate, measured disturbance, and control signals. By optimizing the input and output weights of the MIMO-MPC using particle swarm optimization (PSO), the optimal MIMO-MPC for simultaneous control of the LFC and EVs, is able to stabilize the frequency fluctuation and maintain the desired battery SOC at the certain time, effectively. Simulation study in a two-area interconnected power system with wind farms shows the effectiveness of the proposed MIMO-MPC over the proportional integral (PI) controller and the decentralized vehicle to grid control (DVC) controller.

• 대한간호학회지
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• 제11권2호
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• pp.69-82
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• 1981

The purpose of this study was to compare the needs among the patients of hyperthyroid, malignant tumor and normal adult to clarify the level of the need for the patient of hyperthyroid. We analysed relationships between their personal characteristics and their needs to contribute comprehensive nursing care for the patient of hyperthyroid. The . subjects were chosen from 60 persons who visited for general physical examination at Ewha Woman's University Medical Center., 72 patients having diagnosis with hyperthyroidism, and 72 patients admitted with malignant tumors at atomic neuclear medical center. The data was collected from September 1 to December 31, 1980, and the study population was selected by means of convenience sampling. The data was analysed by means of the standard deviation and analysis of variance. The results were as follows: 1. In the patients having hyperthyroid, male to female ratio was 1 :13.5, and incidence was peak at the age groups of 20 to 40. 2. In compare with the needs among 3 groups, there are significant relationships: the patient of cancer has shown the highest score with Achievement, Aggression and Dominance, the patient of hyperthyroid shown higher and the normal adult shown low score. .In the need related with sex, there is significant relationship: the normal adult has shown highest score, the patient having hyperthyroid shown the higher score and the patient of cancer shown the low score. 3. Tn compare with Whang's Edward personal preference schedule, the Hyperthyroidism shown relatively higher needs for aggression, dominance, exhibitionism and sex.

• 동의신경정신과학회지
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• 제19권3호
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• pp.171-178
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• 2008

Objective: The purpose of this study is investigation of relationship between HRV(Heart Rate Variability) and Hwa-Byung in general population. Methods: HBDIS(Hwa-Byung Diagnostic Interview Schedule) was carried out for 658 participants in Wonju Cohort study that include short term electrode HRV test. We also classified whole participants into sex. Collected data was analyzed by the Mann-Whitney U test. Result: SDNN(Standard Deviation of NN interval) was significant different in HRV between Normal and Hwa-Byung of male participants. Conclusion: In the findings of this study, Hwa-Byung is not closely related to the autonomic nerve system.

• 산업공학
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• 제13권2호
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• pp.225-233
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• 2000

In this paper, we develope a genetic algorithm for the erection scheduling in shipbuilding. Erection, the final manufacturing stage of shipbuilding, involves the landing and joining of blocks at drydock. Since several ships are built simultaneously at the same drydock and they compete with the common constrained production resource such as labor, space, and crane, we should consider both ship-specifics and common resource constraints for the desirable erection scheduling. Ship erection should also satisfy the predetermined dock cycle given from higher level production planning. Thus, erection schedule of a ship can be represented as a PERT/CPM project network with its own deadline. Since production resources are shared, the erection scheduling become the so-called multi-project scheduling problem with limited resources, which can not be solved easily due to the large size of project network. We propose a function as a minimization of load index which represented the load deviation over time horizon considering the yard production strategy. For the optical parameter setting, we tried various experiments. We verified that the proposed approach was effective to deal with the erection scheduling problem in shipbuilding.

• Journal of Forest and Environmental Science
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• 제40권3호
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• pp.188-195
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• 2024

The study examined the perceived benefits and knowledge level of the mushroom farmers on mushroom production in selected local governments area of Oyo State, Nigeria. The data obtained were analyzed with frequency, percentage, mean and standard deviation. Multistage sampling procedure was used to select 143 respondents using questionnaire and interview schedule. From the result it was affirmed that the majority (63.0%) of the respondents were males, also about 81.8% of the farmers were married. Radio (96.5%) was the most common source of information available to farmers, seconded by family and friends 86.0%. Based on the distribution of the knowledge level of farmers in mushroom production (63.6%) of the farmers had highest knowledge in mushroom production with the mean score (9.28). Majority (64.3%) of the mushroom farmers perceived mushroom production to be of benefit to them, with the mean score (10.35). It was concluded that majority of the farmers that had knowledge of mushroom production needs training in some specific aspects of the production process. It is recommended that research institutes, extension agents and Non-governmental organizations needs to organize training to enlightened and provide necessary information needed to the farmers on mushroom production.

• 화약ㆍ발파
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• 제38권4호
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• pp.16-25
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• 2020

터널 발파 굴착 시 발생되는 진동을 저감시키기 위해 사용되는 MSP(Multi-setting smart-investigation of the ground and pre-large hole boring method) 공법은 1회 천공 시 수평방향으로 50m에 달하는 장거리를 천공하기 때문에 고 중량 해머비트와 롯드의 일방향 회전으로 롯드의 처짐과 우향 현상이 동반된다. 이는 전문가의 경험과 시공 이력을 바탕으로 가변적인 세팅을 통해 일부 보정되고 있다. 그러나 암반 특성, 장비 상태, 경험 부족 등은 목표 지점으로부터 천공 오차를 발생시키는 원인이 되며, 큰 이격 오차 발생 시 재시공으로 인한 공기 증가와 경제적 손실이 발생된다. 본 연구에서는 딥러닝을 활용하여 상황별 천공 장비의 최적 세팅조건 산정 모델을 개발하였으며, 학습 과정에서 발생 가능한 과적합 문제를 방지하기 위해 dropout, early stopping, pre-training 기법들을 사용하여 향상된 결과를 도출하였다. 본 연구를 통해 대구경 천공 장비의 상황별 초기세팅 산정 모델 개발의 높은 가능성을 확인했으며, 지속적인 데이터 수집과 다양한 인자들의 추가 학습을 통해 최적화된 세팅 가이드라인을 개발할 수 있을 것으로 기대된다.