• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.313-319
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• 2014

Additional train scheduling is often required to increase the capacity of transporting passengers or freight. In most previous studies on scheduling additional trains, operation time of the added train is designated first; and then the train operation feasibility is examined. However, it is often difficult to apply this approach to domestic trains because the density of the railroad network in Korea is high and various types of trains are in use. Moreover, for freight trains, it is even more challenging because the delay is accumulated due to lower priority whenever a freight train and a passenger train contend for a common segment of rail. In this paper, we address the additional train scheduling problem which entails finding a feasible schedule for an additional train having a fixed departure time or departure time windows. The problem is modeled as a mixed integer programming and a column generation technique is used to solve it.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.593-601
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• 2020

This study was conducted to analyze the physical strain with heart rate monitor in timber harvesting operations in order to reduce occupational accidents. The timber harvesting activities are manual cutting(felling, limbing and bucking) with a chainsaw and extraction by cable yarder. The study took place on Japanese larch stand. The average height was 26m and average diameter at breast height(DBH) was 3 7cm. The havest unit was gentle slope to steep slope. Results showed that the heart rate increases for chocking, felling, limbing and bucking were 94.0%, 87.9%, 84.8% and 56.4% respectively. The rate of Work Load Index was higher in the limbing(61.4%) activity than other activities chocking(55.2%), felling(54.1%) and bucking(32.1%). During 50% working heart rate test it was found that limbing(1.09), chocking(1.05) and felling(1.04) was exposed to high work intensity compared to bucking(0.83). The results showed that maximum acceptable work times(felling, chocking and limbing) were 2.30 hour, 1.85 hour and 1.60 hour respectively. To avoid occupational accidents, timber harvest workers may use a suitable working hour schedule to felling, chocking, limbing.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.89-96
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• 2024

In many cases, fishing vessels operate on a schedule that leads to departure, sailing to the fishing spot, fishing, and sailing to the port of return. Consequently, most of the captains of fishing vessels operated on a single-person navigation duty system rarely have time to rest, resulting in frequent accidents owing to drowsy operation. In addition, accidents frequently occur when a tired captain leaves his duty to an unqualified seaman who does not have the basic knowledge of navigation and sleeps in the bedroom. This problem has been discussed for a long time; however, it has not been solved yet because of lack of proper countermeasures. As a measure to reduce these accidents, this article proposes a certification system for navigational-duty crew of fishing vessels.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.361-370
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• 2020

We developed a heavy-duty work class ROV trencher named URI-T (Underwater robot it's trencher) that can conduct burial and maintenance tasks for underwater cables and small diameter pipelines. It requires various supporting systems, including a dynamic positioning (DP) vessel, launch and recovery system (LARS), A-frame, and winch in order to perform burial tasks because of its dimensions (6.5 m × 5.0 m × 4.5 m, 20 t) and the tough working environment. However, operating a DP vessel has disadvantages as it is expensive to rent and operate and it is difficult to adjust the working schedule for some domestic coast construction cases. In this paper, we propose a method using a barge instead of a DP vessel to avoid the above disadvantages. Although burying the cable and pipeline using a barge has lower working efficiency than a DP vessel, it can save construction expenses and does not require a large crew. The proposed method was applied over two months at the construction of the water supply in Yokji-do, and the results were verified.

• Journal of Agricultural Extension & Community Development
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• v.22 no.1
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• pp.69-78
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• 2015

This study conducted IPA of each item related to the farm party operation aiming at the participants to farm parties. The survey was carried out on the participants to the farm parties held in Damyang County from October 11th to November 22nd, 2014, and 103 questionnaires were used for the final analysis. The specific results of the IPA are as follows. In the first quarter of 'maintenance and management performance' are included the total of seven items. They are a harmonious view with the surrounding environment, friendliness of the farmer and the party staff, posting the event schedule and providing the program, proper disposition of the staff in the farm, an exchange among farm party participants, food that makes use of farm produce and the convenience of gaining information. In the second quarter of 'intensive improvement' are included eight items. They are cleanliness of the facilities such as restroom and basin, providing the pamphlets or promotion materials of the farms in the farm party, things to experience utilizing the farm produce grown in the host farm, various events, smooth progress of the farm party program, inclusion of the indigenous native food, variety of things to buy including farm produce and information delivery about the farm produce on sale.

• 전기의세계
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• v.18 no.1
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• pp.24-29
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• 1969

This is preliminary study concerning the future construction and operation of 345KV power transmission line in Korea which will be added to the existing 161KV power system by the end of 1970 in order to increase the power carrying capacity between Seoul and Pusan area; 350 kilo meters aparts, in accordance with the ambitious second five years power development schedule of Korea Electric Company. The result of this study says that an intermidiate switching station should be installed at the middle position of the line to improve the transient stability of the system, considerable amount of capacitors or synchronous condenser are to be installed to reduce the voltage drop at receving end of line during the heavy load hours, and also in some measure to avoid the voltage rise by self-excitation of power generators during the light load hours and while energizing the line. This is the first attempt to realize the EHV power transmission line in Korea so that the additional study is necessary on the kind and size of conductors, the necessary number of insulators and the suitable clearance distances between conductor and steel tower or earth from the technical and economical view points. These are necessary steps to be taken by the writer before getting into the calculation on the transient stablity of the power system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.4
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• pp.85-95
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• 2007

Single PPM Quality Innovation activity made a great contribution to strengthening the quality competitiveness and the international competitiveness for the domestic small and medium enterprises. But it doesn't work to companies that deal with the particular products for the difficulties during the promotion and the business management. Then, SQ-Mark, which is currently adopted to domestic automobile companies, was benchmarked and studied for its accessibility and solutions. Quality Innovation activity in the particular industry is requested to conduct the confirmation and the inspection in deeper level caused by the specialty of product itself, product engineering manufacturing processes. This study improved 6 steps of the Single PPM activity so that the Single PPM Quality Innovation activity is progressed well for the Mold industry especially among the particular industries. It shows the improvement to the management of the delivery schedule, which has been problematic, if adopted to the relating industries based on this study, it is anticipated to help the corporate operation much.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.10
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• pp.27-35
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• 2018

In this paper, a fundamental study for developing and introducing a new assessment method of the 'Energy Performance' in G-SEED that uses dynamic building energy simulations was conducted by comparing and analyzing the corresponding issues of domestic and foreign green building certification systems. The most significant part of the new assessment method to be developed was a development of a modeling guideline for a reference building using dynamic building energy simulations. In this paper, the composition and detailed contents of the guideline was created to comply with domestic energy codes. In addition, one of the most influential part of the result in the simulations, the 24-hour building operation schedule for a reference building, was created considering the equity with the ECO2 program that is the evaluation tool of one of the current assessment methods in the "Energy Performance". In order to improve the completeness of this guideline, it is necessary to continue the process of supplementation in the future, however, this paper is expected to be of great significance as the beginning of the research.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.53-63
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• 2017

The increasing of wind power penetration level presents challenges in classical optimal reactive power dispatch (ORPD) which is usually formulated as a deterministic optimization problem. This paper proposes a two-stage stochastic programming model for ORPD by considering the uncertainties of wind speed and load in a specified time interval. To avoid the excessive operation, the schedule of compensators will be determined in the first-stage while accounting for the costs of adjusting the compensators (CACs). Under uncertainty effects, on-load tap changer (OLTC) and generator in the second-stage will compensate the mismatch caused by the first-stage decision. The objective of the proposed model is to minimize the sum of CACs and the expected energy loss. The stochastic behavior is formulated by three-point estimate method (TPEM) to convert the stochastic programming into equivalent deterministic problem. A hybrid Genetic Algorithm-Interior Point Method is utilized to solve this large-scale mixed-integer nonlinear stochastic problem. Two case studies on IEEE 14-bus and IEEE 118-bus system are provided to illustrate the effectiveness of the proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.384-392
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• 2015

This paper presents an economic assessment of large-scale Li-ion battery energy storage systems applied to Korean power system. There are many applications of the battery energy storage systems (BESSs) and they can provide various benefits to power systems. We consider BESSs to the energy time-shift application to Korean power system and evaluate the benefits from the application of BESS in the social perspective. The mixed integer programming (MIP) algorithm is used to resolve the optimal operation schedule of the BESS. The social benefits can include the savings of the fuel cost from generating units, deferral effects of the generation capacity, delay of transmission and distribution infra construction, and incremental CO2 emission cost impacts, etc. The economic evaluation of the BESS is separately applied into Korean power systems of the Main-land and Jeju island to reflect the differences of the load and generation patterns.