• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.7-10
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• 2001

This paper provides a solution for the problem of efficiency decrease caused by load variation. A novel control scheme of tracking the PT's operation frequency for the maximum efficiency is proposed. As a result, a high efficiency over $80\%$ has been achieved even under the output-current decrease down to $10\%$ of the full load current.

• Journal of Forest and Environmental Science
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• 제24권1호
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• pp.47-51
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• 2008

가지치기 작업은 보통 묘목의 식재 후 수고가 6 m 전후일 때 1차 작업을 실시하고 수고 12~13 m 전후일 때 2차 작업을 실시한다. 옹이가 없고 통직한 목재를 생산하기 위해서는 도구나 기계에 의하여 가지치기 작업이 필요하다. 가지치기 작업방법에는 자동지타기를 이용하거나 동력 고지톱을 이용하는 등 여러 가지 방법이 있지만 본 연구에서는 가지치기 작업에 일반적으로 가장 많이 활용하고 있는 인력고지톱에 의한 가지치기작업을 조사하였다. 조사수종은 강원도 지역을 중심으로 분포하고 있는 소나무, 잣나무, 리기다소나무를 대상으로 하였다. 조사대상 수고는 10~16 m 내외로서 가지치기 후 지하고의 높이는 6.2~6.7 m 내외로서 인력고지톱에 의한 가지치기 작업능률은 4~6 m의 작업높이의 경우 1본당 소나무 3.46분, 잣나무 5.06분, 리기다소나무 4.44분이 소요되었고, 1일 작업능률은 소나무 104본, 잣나무 64본, 리기다소나무 81본으로 나타났다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1370-1376
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• 2009

Reinforcing steel works should be carefully controlled by the construction manager considering the severe fluctuation of the price of reinforcing steel bars and for the safety of structure in building constructions. In particular, preparing rebar placing drawings needs more effort and time than before because of the emergence of higher and more complicated buildings. Moreover, the experience of field engineers or foremen (fabricators or detailers) in preparing placing drawings gives rise to the differences in fabricated bar type and quantity of bars used. To address these problems, this study proposed the support system in preparing placing drawings for reinforcing steel works efficiency. In the near future, if this system can be made available on the web, multiple end-users will be able to share the result; the efficiency of rebar supply chain management will also be improved.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.66-73
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• 2011

With rapid industrialization, electric power consumption has been increasing every year in Korea and in other countries. The provision of additional power stations to produce more electricity is one possible response to this steady increase in consumption. Another alternative is to improve the efficiency of existing stations through timely and effective maintenance works. Since the construction of a new power plant involves a large amount of capital as well as difficulties in the selection of sites, the improvement of existing power stations' efficiencies is often a preferred solution. Therefore, this paper focuses on maintenance project management to address this issue. Among several types of maintenance works, this paper concentrates on planned outage maintenance (POM). This focus arises from the critical impact of POM on other maintenance work, as well as the entire process of electricity production. Unlike other maintenance work, POM is done on the basis of mid and long-term plans. In addition, only POM works are conducted during the outage of all power plants. To evaluate the efficiency of POM works, budget data relating to 164 POM projects between 2001 and 2008 was collected from 7 sites in South Korea. Data envelopment analysis (DEA) was selected as a methodology for evaluation. From this analysis, comparative study was used to determine the categories of projects that had performed well, and those with the most optimized budget structures. Moreover, through discussion with industry, this research develops a feasible proposed method by which to enhance the efficiency of POM projects.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.116-118
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• 2000

This paper proposes an efficient method of On-Line Economic Load Dispatch(ELD) using Evolutionary Programming(EP) technique at Kwangyang steel works. The economic operation of steel works is done by experienced engineer. So far, there is no formulation and algorithm of economic operation of steel works. In this paper, we propose the formulation and On-Line algorithm of economic operation of steel works. The EP technique is the kind of Evolutionary Computation(EC) which has become a candidate for many optimization applications due to its flexibility and efficiency. Based on the EP technique, the proposed algorithm is capable of not only solving the economic problem, but also obtaining the global optimal solutions within reasonable execution time. To validate our proposed approach, the algorithm is demonstrated on many sample systems and compared to actual values of steel works.

• 한국산림과학회지
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• 제101권4호
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• pp.729-736
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• 2012

산림청은 산림분야 녹색 일자리 창출의 일환으로 숲가꾸기 사업에 중점을 두고 있다. 숲가꾸기의 목표는 숲을 효율적으로 가꾸어 경제림을 조성하고 동시에 생태적으로 안정된 임분구조를 유지하는데 있을 뿐만 아니라 일자리를 만들고 탄소흡수원을 확충하는 등 여러 가지 효과를 낳는 매우 중요한 사업으로 그 중요성이 더욱 부각되고 있다. 이러한 목적을 효율적으로 달성하기 위해 숲가꾸기 사업에 투입되는 여러가지 투입요소(재료비, 노무비, 경비)에 따른 산출물(작업량, 제거본수, 사업면적)의 경영효율성을 DEA 기법을 이용하여 분석하였다. 그 결과 총 52개 숲가꾸기 대상지 중 19개 지역에서 효율성이 최적인 것으로 나타났다. 참조횟수가 높은 지역은 6개(소반 8-0-3, 9-3-3, 6-0-3, 7-0-6, 1-0-5, 3-0-3)로 나타났으며, 가장 높은 지역은 소반 3-0-3으로 나타났다. 참조횟수가 많이 나온 지역의 의미는 비교대상지로부터 숲가꾸기 사업의 벤치마킹을 해야 하는 우수지역으로 선정된 것을 나타낸다.

• 한국도로학회논문집
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• 제20권2호
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• pp.109-118
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• 2018

PURPOSES : This study evaluates the efficiency of snow removal operation resources using data envelopment analysis (DEA). The results of this study can help decision-making strategies, especially for resource allocation for snow removal works on national highways. METHODS : First, regional road management offices (DMUs) for efficiency evaluation were set up, and a database (for years 2012-2016) for analysis was formed. Second, DEA was carried out by selecting input and output variables based on the constructed database. Lastly, based on the results of the DEA, the efficiency of each regional road management office was evaluated. In addition, the potential for future improvement was determined. RESULTS : The results showed that there was a large variation in efficiency of snow removal operation resources by regional offices. CONCLUSIONS : The results of this study imply that the evaluation of efficiency for snow removal operation resources is important when decisions related to snow-removal strategies are made by road management offices.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2013년도 자성 및 자성재료 국제학술대회
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• pp.90-90
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• 2013

Since discovery, NdFeB permanent magnet has replaced application of the conventional magnets rapidly because of its superior physical and mechanical properties. With increasing consumption of power combined with energy resource depletion, energy efficiency is becoming more and more inportant. According to recent reports, almost almost half of the electric power is consumed by motor, and NdFeB magnets which are the core component of the motor play a key role on improving energy efficiency of the devices. In parallel with finding alternatives energy resources, research works improving energy efficiecy have been conducted world wide. Althogh NdFeB magnets usage have been expanded to various applications, key materials such as Nd and Dy, resouces lean heavily on specific area, China. Magnetic industry revently experienced skyrocketing price fluctuatioin of rare earth at around 2008. Chineses government's regulations worsened the situation and arose a necessity to develop methods to minimize rare earth use. In this presentation, POSCO's recent research works on rare earth reduction is presented including novel powder alloying method using nitrate precursors. Also, future R&D plans for rare earth free magnets is briefly introduced as well.

• 로봇학회논문지
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• 제16권3호
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• pp.207-215
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• 2021

There is a risk of serious injury to workers who work at height in pier construction process. By using auto climbing formwork system that does not need to dismantle and reinstall formworks, it is possible to improve work efficiency and safety of workers. However, auto climbing formwork system still requires workers to work on a pier for rebar connection works and so on. In order to eliminate works by workers on the pier, robot manipulators with special end effectors are proposed. Through analysis of works on the pier, three specialized end effectors which are a gripper, a rebar coupler press, and a concrete vibrator, are suggested. Also, new pier construction scenario by the suggested system is confirmed using 3d modeling. It is expected that the proposed system and method enables pier construction without workers on piers. It will increase safety and efficiency of pier construction.

• 대한전기학회논문지:전력기술부문A
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• 제50권7호
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• pp.318-323
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• 2001

This paper proposes an efficient method of On-Line Economic Load Dispatch(ELD) using Evolutionary Programming(EP) technique at KwangYang steel works. The economic operation of steel works is done by experienced engineer. So far, there is no formulation and algorithm of economic operation of steel works. In this paper, we propose the formulation and On-Line algorithm of economic operation of steel works. The EP technique is the kind of Evolutionary Computation(EC), which has become a candidate for many optimization applications due to its flexibility and efficiency. Based on the EP technique, the proposed algorithm is capable of not only solving the economic problem, but also obtaining the global optimal solutions within reasonable execution time. To validate our proposed approach, the algorithm is demonstrated on many sample systems and compared to actual values of steel works.