• 콘크리트학회논문집
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• 제16권2호
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• pp.205-212
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• 2004

최근에 환경문제가 대두됨에 따라 재활용을 이용한 건설재료의 개발 또한 관심이 대두되고 있다. 특히, 대부분 매립을 하여 처리하는 폐수지의 경우에는 심각한 환경문제를 일으키고 있다. 본 연구에서는 안전한 건설자원을 확보하고 환경을 보호하는 차원에서 재활용 PET 수지를 이용한 폴리머 콘크리트를 활용하였다. 폴리머 콘크리트의 많은 장점에도 불구하고, 높은 경화수축량과 열에 대한 민감성은 폴리머 콘크리트의 단점으로 지적되고 있다. 본 연구에서는 재활용 PET 수지를 이용한 폴리머 콘크리트의 기본적인 물성치이자 결점인 경화 수축과 그로 인한 길이 변화, 온도팽창계수, 압축강도를 측정하고, 그러한 결점을 보완하고자 Mont.를 특별한 결합재 없이 첨가제로만 사용하여 그 적용 가능성을 알아보고자 하였다. 그 결과, PET 재활용 폴리머 콘크리트는 일반적인 폴리머 콘크리트와 여러가지 물성치에서 비슷한 경향을 보였으나, 중합반응이 일어나는 시간이 상대적으로 긴 것으로 나타났다. 또한, 본 연구를 통하여 Mont.가 경화수축과 길이 변화 그리고 온도팽창 계수, 강도 등의 물성치에 영향을 미치는 것으로 나타났으며, 첨가제로써의 사용성이 있는 것임이 확인되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.338-339
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• 2011

본 논문은 전력시스템을 구성하는 수 많은 송전선로용 보호계전시스템의 정정값 유효성을 자동으로 판단하는 시스템에 대해 설명한다. 전력계통의 변경에 따라 송전선로 보호계전기의 동작값에 대한 재검토가 필요하나 그 실행은 정정자의 판단에 의해 자의적으로 실행되는 문제점이 있다. 따라서, 한전에서는 주요 정정요소에 대한 주기적인 자동 정정산출을 통해 정정값의 변화 추이를 모니터링 하고 그 변화가 일정 범위를 벗어날 경우 사용자에게 경보하여 시기적절한 재정정이 이루어 질수 있는 시스템을 개발하여 운영하고 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.286_287
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• 2009

In this paper, the protectability of distance relay is furtherly researched. Based on the probabilistic modeling of the measurement errors, the protectability of three zones is presented in detail by considering their different protection aims denoted by sensitivity and selectivity. The optimal setting for the each zone can be obtained to provide a reference for the practical application.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.29-35
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• 2008

With long time setting, zone 3 impedance relays are considered insensitive to power swings, and their operation condition during power swings is seldom analyzed. Instead of ti me-consuming simulation to the swing loci, their operation condition is directly quantified by polynominal functions in this paper to find the critical swing angle and frequency for relay operation under different relay settings and system parameters. It is found: (1) the swing loci are more densely populated inside than outside of the protection region, which corresponds to long residence time and possible relay operations; (2) the relays may be sensitive to load encroac hments and stable power swings with different relay settings and system parameters; (3) the critical swing frequency may be in the range of low-frequency power swings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.38-41
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• 2001

This paper presents a digital current differential protection algorithm for a transformer in power system. This algorithm uses an FIR filter to improve the performance of the relay. This paper presents a practical method setting the operating slope of the relay and reduce ct mismatch. A series of EMTP simulation results have shown effectiveness of the algorithm under various type of transformers and conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1221-1223
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• 1999

The safety loads in a nuclear power plant perform a critical function to plant safety. The design of the electrical auxiliary system should ensure the availability and adequacy of the power supply, and therefore, the frequency and voltage relaying schemes should be installed on the system to monitor and protect against the degraded system condition. If unforeseen contingencies degrade the switchyard frequency and voltage to below the minimum values, the safety related bus should properly be transferred to alternate power source. This paper presents guidelines associated with the protection of nuclear power plants during frequency/voltage decay and the steady-state and dynamic analysis of auxiliary power system that should be performed to support the degraded voltage relay(second level undervoltage relay) setting.

• 무역상무연구
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• 제27권
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• pp.215-232
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• 2005

China had revised Foreign Trade Law in order to fulfill its WTO commitments and duties, and fully exercise its rights and benefits as a WTO member. The main contents of the revised Foreign Trade Law as followed. For the first time, individuals are allowed to conduct foreign trade. Intellectual property is an important component of foreign trade, and protecting intellectual property rights is a key issue. A chapter on Intellectual property protection is one of the major additions to the Foreign Trade Law. New sections have also been added to allow and provide guidance for conducting investigations and seeking relief. Finally, the new law beefs up and clarifies enforcement procedures. It regulates the setting up of early warning and emergency systems and a foreign trade statistics system.

• Safety and Health at Work
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• 제8권2호
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• pp.226-230
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• 2017

The performance of sound barriers was evaluated to determine their technical effectiveness and practicality in reducing noise exposures to operating engineers in construction. Commercially purchased sound dampening mats (SDMats) were installed inside three heavy-equipment engine compartments. Sound pressure levels (SPLs) were measured before and after installing the SDMats while the equipment was on idle and full-throttle settings where it normally operates. SPLs inside the heavy-equipment operator cabs were significantly reduced by 5.6-7.6 dBA on the full-throttle setting following installation of the SDMats (p < 0.01). The evaluated engineering control intervention was simple to install, affordable, and substantially reduced the engine noise reaching the heavy-equipment operator, potentially reducing reliance on hearing-protection devices to protect construction workers from noise exposures.

• Computers and Concrete
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• 제21권5호
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• pp.531-538
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• 2018

The slag through sieve #4 replaced the natural fine aggregate in different proportions (0-50%) to make ready-mixed soil and slag (RMSAS). The fresh properties studied, and the concrete specimens were produced to test the hardened properties at different ages. Results showed that the workability of RMSAS decreases when the replacement increases. The unit weight increases with the replacement. The setting time extends when the replacement decreases and shortens when the replacement increases. The compressive strength, ultrasonic pulse velocity and hammer rebound value increase with the replacement. However, the high-replacement results decrease because of the expansion factor at late age. Resistivity is close and less than $20k{\Omega}-cm$. After the industrial of steelmaking by-products are processed properly, they can be used in civil engineering, not only as a substitute for natural resources and to reduce costs, but also to provide environmental protection.

• KIEAE Journal
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• 제13권1호
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• pp.75-81
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• 2013

The balcony of our apartment building consists of unique construction similar to double skin. It is announced broadly that double skin is very effective system in improvement of natural ventilation and indoor thermal environment, and outdoor sound protection. So, for the improvement of indoor climate and energy saving, many peoples studied about environmental performance of our balcony construction. This study focus on shaft box facade, special form of box window construction. It consists of a system of box window with continuous vertical shafts that extend over a number of stories to create a stack effect. Proto-type was decided by analyzing various types of exiting apartments. Shaft box type balcony was created by setting up shaft space at a part of balcony. Air flow and contribution of air temperature were simulated, performance of shaft box type balcony was compared with existing balcony. Finally, we confirmed that shaft box type balcony has many possibility for improvement of indoor environment.