• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.262-264
• /
• 2005

최근 IT산업의 급격한 부상으로 전력산업에서도 운영시스템이나 설비들이 통합되거나 소형화 및 다양한 가능을 보유하는 둥 많은 변화가 진행되고 있다. 전국의 많은 154kV 배전변전소에는 기존의 유도원판형 보호계전기가 점차 철거되고 기계적인 동작시간차를 고려하지 않아도 되는 디지털보호계전기로 교체되어 있는 중이다. 따라서 배전선로 보호협조 운영기준은 유도원판형 보호계전기만을 고려하여 제정되어 있기 때문에 합리적인 배전계통운영을 위하여 보호협조 운영기준은 현실에 알맞도록 개선되어야 할 것이다. 이 논문에서는 배전 변전소에서 사용중인 디지털보호계전기를 소개하고, 도입에 따른 배전선로 보호협조 방안을 제시하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.5 no.2
• /
• pp.122-129
• /
• 1993

The heat transfer characteristics of the rotating heat pipe with a disc evaporator and a grooved condenser have been investigated by measuring temperature distributions of wall and vapor for various thermal inputs and revolutions per minute. The results showed that the heat transfer coefficients of all types are increased with thermal input and revolutions per minute. The heat transfer coefficient of evaporator with groove (pitch=2.5mm depth=1.5mm) is 25.8% higher than that of evaporator without groove at 500RPM, 150W.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.2101-2104
• /
• 2003

Experimental investigations are performed for the rarefied gas flows in a disk-type drag pump (DTDP). The pump considered in this paper consists of grooved spiral channel on rotors and planar stators. The flow-metre method is adopted to calculate the pumping speed. Compression ratio and pumping speeds for the nitrogen gas are measured under the inlet pressure range of $0.001{\sim}4$ Torr. The maximum of compression ratio was about 3300 for three-stage DTDP, 1000 for two-stage and 100 for single-stage DTDP at zero throughput. The number of stage influences the pumping speed of DPDT

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.577-580
• /
• 2002

In this paper, the pumping performance of the disk-type drag pump which works in the outlet pressure range from 4 to 0.001 Torr is studied experimentally. The pumping characteristics of various drag pumps are performed. The inlet pressures are measured for various outlet pressures of the test pump. The flow-meter method is adopted to calculate the pumping speed. Compression ratios and pumping speeds for the nitrogen gas are measured. The present experimental data show the leak-limited value of the compression ratio in the molecular transition region. The rotational speed of the pump is 24,000rpm. The inlet pressures are measured for various outlet pressures of the test pump. The ultimate Pressures for zero throughput are measured for three-stage, two-stage and single-stage disk-type, respectively.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.11
• /
• pp.143-151
• /
• 1996

Structural reaction injection molding을 이용한 복합재료의 제품 셩형을 위한 모델링 전략을 설명하였다. 사용된 모델은 두 평행한 원판형 mold에 있는 불 균일한 온도조건의 fiber preform을 통과하는 reactive srsin의 방사형 유동을 시뮬레이션 한다. 이러한 모델은 중요한 작동인자와 공정인자(주입온도, mold의 온도, 유량, cavity의 두께와 섬유의 조밀도)등이 유동속도, 변화(monomer, radical, inhibitor) 및 온도분포 등에 미치는 영향을 예견한다. 열전달과 질량전달 및 화학반응을 고려하여 모델을 개발하였다. 중요한 공정인자를 평가하기 위한 효울적인 공정창( process window)을 제공하는데 본 연구의 목적을 두었다. 2차원적인 Lagrangian 방식에 1차원적인 유동과 제한적인 2차원 열전달을 가정하여 모델을 유도하였고, 방정식은 implicit difference scheme에 의해 전개하였다. 이 모델은 Gonzalez-Romero의 실험 결과와 비교함에 의해 확인되었고, 실험결과가 잘 일치함을 보였다.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.3
• /
• pp.40-44
• /
• 1983

A wide band quasi-log periodic microstrip antenna is designed using circular-disc microstrip patches as a basic radiator. The radiating elements are series-fed by a coplanar feeding network which consists of an open circuited feed line with a branch line connected to each radiating element. Experiment results show that the values of VSWR are less than 2.3 over the range of 2.72-3.43 GHz.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1171-1172
• /
• 2015

송전선이나 전기기기의 나선(裸線)부분을 절연하고 동시에 기계적으로 유지 또는 지지하기 위한 절연체와 이것과 일체로 조립된 금구류로 구성된 절연지지물인 애자는 전기적으로 충분한 절연내력을 가지게 하기 위하여 다수의 주름을 만들어 표면에 따른 거리를 크게 한다. 이는 표면이 습하였을 때, 염분이나 먼지 등이 부착하였을 때 절연내력이 저하되는 것을 방지하는 데 효과가 있다. 그리고 재질별(세라믹, 유리, 합성수지 등), 모양별(원판형, 원주형, 중공, 갓형 등), 용도별(전차 선로용, 발전소 또는 변전소용, 통신 선로용 등) 및 사용방법(현수용, 내장용, 인류용, 고정용 등)에 따라 다양하게 분류된다. 본 논문에서는 복합 애자류(composite insulators)의 여러 가지 성능평가 시험방법 중에서 복합 애자의 여러 계면과 연결 금구의 접속부(interfaces and connections of end fittings)에 대한 이상 유무를 확인하는 시험인 수분침투시험평가기술에 대해 고찰하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.9 s.102
• /
• pp.1045-1052
• /
• 2005

Tn this paper. dual rotor disk configuration with a coreless stator is proposed for the Lorentz force type integrated motor hearing system. An experimental compensation for the effects of high order harmonics is performed using the digital controller of the experimental setup. The runout profile and rotor unbalance are also identified by the extended influence coefficient method. The experimental results confirm that this compensation scheme effectively attenuates the rotor vibration all over the operating range of rotational speed.

• Journal of the Korean Geosynthetics Society
• /
• v.13 no.4
• /
• pp.77-85
• /
• 2014

The helical pile has become popular with some constructional advantages because relatively compact equipment is needed for installing helical piles. However, field loading tests for estimating the bearing capacity of helical piles have drawbacks that the required dead load should be as much as the operation load, and reaction piles or anchors are required. In this paper, the bi-directional load test without necessity of reaction piles and loading frames was applied to the helical pile, and the load-settlement curves of the helical piles were measured. The bi-directional load test was performed in two separate stages with the aid of a special hydraulic cylinder whose diameter is equal to that of the pile shaft. In the first stage, the hydraulic cylinder is assembled immediately above the bottom helix plate, and the end bearing capacity of the helical pile is measured. In the second stage, the hydraulic cylinder is assembled above the top helix plate, and the skin friction of the helical pile is measured. The pile loading-test program was carried out for the two different helical piles with the shaft diameter of 89 mm and 114 mm, respectively. However, the configuration of helix plates is identical with three helix plates of 450-, 350-, 200- mm diameter. Results of the bi-directional load test were verified by the conventional static pile loading test. As a result, the bearing capacity estimated by the bi-directional load test is in good agreement with the result of the conventional pile loading test.

• Electric Engineers Magazine
• /
• v.200 no.4
• /
• pp.22-29
• /
• 1999

발전기도 여타 주요 전기설비와 마찬가지로 다중 보호되도록 하여 안전을 도모하고 있으며 보호방법에 있어서는 유도원판형 등 아날로그 방식에서 디지털 방식으로 발전, 변경되고 있지만 보호의 종류, 보호 목적 등에 있어서는 종전과 다를 바가 없다.