• 한국정보전자통신기술학회논문지
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• 제15권4호
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• pp.223-229
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• 2022

본 논문은 보일러에 사용되는 점화트랜스에 대해 연구를 하였다. 점화봉 길이와 점화봉 간격 변화에 관계없이 출력주파수는 59.5~61.3Hz 사이에서 측정되었고 저주파 회로는 정상적으로 동작된 것을 알 수 있었다. 점화봉 간격이 2~10mm 변화를 주었을 때, 점화봉 길이가 30cm에서는 2.8A에서 3.45A까지 측정되었다. 점화봉 길이가 500cm에서는 9.37A에서 14.5A까지 측정되었고 1000cm에서는13.2A에서 32.6A까지 측정되었다. 점화봉 길이와 점화봉 간격이 증가 될수록 전류는 증가되었다. 2차코일 출력전압을 측정한 결과. 점화봉 길이가 30cm에서는 AC 0.84kV~AC 1.75kV로 측정되었고 500cm 인 경우는 AC 1.17kV~AC 1.944로 측정되었고 1000cm에서는 AC 1.4kV~AC 7.18kV까지 측정되었다. 점화봉 길이와 점화봉 간격이 증가되면 2차코일 출력전압도 증가되었다. 점화트랜스의 출력전압 측정한 결과, 점화봉 길이가 30cm에서는 DC 1.11kV~DC 1.57kV 까지 측정되었고 500cm 인 경우는 DC 2.49kV~DC 3.72kV, 1000cm에서는 DC 3.78kV~DC 9.42kV까지 측정되어서 점화봉 길이와 점화봉 간격이 증가되면 출력전압이 증가된 것을 알 수 가 있었다.

• 한국결정성장학회지
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• 제30권2호
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• pp.47-54
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• 2020

본 연구에서는 밝고 화사한 적색 및 황색의 착색 특성을 가지며, 우수한 발광특을 가진 새로운 무기 형광 안료를 개발하기 위하여, A₃V₅O₁₄ (A = K and Rb) 및 Cs₂V₄O₁₁를 water assisted solid state reaction(WASSR) 방법과 고상법을 혼합하여 합성을 하였다. 합성한 A₃V₅O₁₄ (A = K and Rb ) 및 Cs₂V₄O₁₁ 샘플은 AVO₃ 및 AV₃O₈ (A = K, Rb and Cs)가 불순물로 다소 확인되었으나, trigonal 구조의 A₃V₅O₁₄ (A = K and Rb)와 orthorhombic 구조의 Cs₂V₄O₁₁가 주상으로 확인되었다. A₃V₅O₁₄ (A = K and Rb)와 Cs₂V₄O₁₁는 자외선 영역에서 강한 광흡수를 나타내었으며, 각각 적색광 및 녹색광 발광을 나타내었다. 또한, 합성된 A₃V₅O₁₄ (A = K and Rb)는 a* 값 (+ : 적색도, -: 녹색도)은 각각 + 35.5와 + 45.9를, Cs₂V₄O₁₁는 b* 값(+: 황색도, -: 청색도)는 + 50.3을 나타내었으며, 45 이상의 L* 값(명도)을 가지고 있어, 밝고 화사한 느낌을 구현하기위한 황색안료로 응용이 가능할 것으로 기대된다.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.386-393
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• 2004

분산시스템에서 비집중화된 방법으로 부하균형을 유지하기 위해서는 네트워크상의 각 노드는 다른 노드들의 부하상태정보를 가져야만 한다. 네트워크상에 v 개의 노드가 존재할 때 모든 노드간에 부하정보를 교환하기 위해서는 $Ο({v^2})$의 트래픽 오버헤드가 필요하게 된다. 이 논문에서는 분산된 노드간에 동기적으로 동작하는 부하균형 알고리즘을 제시한다. 이를 위해 먼저 SBIBD(Symmetric Balanced Incomplete Block Design)에 근거하여 (v,k+1,1)구조에 의해 $v={k^2}+k+1$ 개의 노드간의 통신을 위해 2k 정규그래프 구조를 갖는 네트워크 토폴로지를 구성하였다. 이 망에서 동작하도록 고안된 부하균형 알고리즘은 Ο(v√v)의 메시지 오버헤드를 가지면서 각각의 노드가 v개의 모든 노드에 대한 부하상태정보를 가지도록 한다. 또한 이 알고리즘은 모든 링크가 부하상태정보 전송을 위해 √v의 동일한 트래픽을 갖도록 설계되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1091-1093
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• 1999

This paper discusses the surveying of a power transmission line using Real Time Kinematic(RTK) GPS technology. The use of RTK provides users with an accurate position at the moment in time. Application result of a 765kV transmission line surveying proved to be more accurate and efficient than using a traditional EDM (Electro-magnetic distance measurement) method. More, decrease in numbers of trees cut down which is a major cause of public discontents was achieved. Improvements in doing a surveying of a power transmission line using GPS is expected in the future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1647-1649
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• 1998

This paper describes the power frequency voltage and its countermeasure when a 765 kV transmission line is directly connected to a 345 kV line and operated at 345 kV voltage. The summary of this result is as follows : The western route of 765 kV transmission line doesn't need any countermeasure to reduce the power frequency voltage at the receiving end. The eastern route of 765 kV transmission needs 100 Mvar(3 phase) capacity of shunt reactor at the receiving end to reduce the power frequency voltage. The use of shunt reactors in the 765 kV transmission lines has unexpected problems, one of which is induction of high voltages on a de-energized circuit of two parallel lines. This paper examined the problem of resonance on two parallel transmission circuits in one routes.

• Journal of Radiation Protection and Research
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• 제43권1호
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• pp.1-9
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• 2018

Background: In this study, we investigate the image quality of virtual monochromatic images synthesized from dual-energy computed tomography (DECT) at voltages of 80/140 kV and 100/140 kV. Materials and Methods: Virtual monochromatic images of a phantom are synthesized from DECT scans from 40 to 70 keV in steps of 1 keV under the two combinations of tube voltages. The dose allocation of dual-energy (DE) scan is 50% for both low- and high-energy tubes. The virtual monochromatic images are compared to single-energy (SE) images at the same radiation dose. In the DE images, noise is reduced using the 100/140 kV scan at the optimal monochromatic energy. Virtual monochromatic images are reconstructed from 40 to 70 keV in 1-keV increments and analyzed using two quality indexes: noise and contrast-to-noise ratio (CNR). Results and Discussion: The DE scan mode with the 100/140 kV protocol achieved a better maximum CNR compared to the 80/140 kV protocol for various materials, except for adipose and brain. Image noise is reduced with the 100/140 kV protocol. The CNR values of DE with the 100/140 kV protocol is similar to or higher than that of SE at 120 kV at the same radiation dose. Furthermore, the maximum CNR with the 100/140 kV protocol is similar to or higher than that of the SE scan at 120 kV. Conclusion: It was found that the CNR achieved with the 100/140 kV protocol was better than that with the 80/140 kV protocol at optimal monochromatic energies. Virtual monochromatic imaging using the 100/140 kV protocol could be considered for application in breast, brain, lung, liver, and bone CT in accordance with the CNR results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1341-1343
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• 1995

The maximum transmission voltage in our country is going to change 345kV into 765kV owing to the increase of Electrical Power Demand and power System Stability. Our company is developing 800kV GIS and 765kV Transformer which are main equipments in 765kV substation. This paper describs the specification on 800kV GIS which we prepared for 800kV 8,000A 50kA GIS development. This specification is supported by Public Standards and Data. And, we are designing the 800kV GIS on this specification and drawing up the 800kV GIS layout for type test.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권5호
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• pp.519-525
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• 2015

Positive bias stress-induced instability in amorphous indium-gallium-zinc-oxide (a-IGZO) bottom-gate thin-film transistors (TFTs) was investigated under high $V_{GS}$/low $V_{DS}$ and low $V_{GS}$/high $V_{DS}$ stress conditions through incorporating a forward/reverse $V_{GS}$ sweep and a low/high $V_{DS}$ read-out conditions. Our results showed that the electron trapping into the gate insulator dominantly occurs when high $V_{GS}$/low $V_{DS}$ stress is applied. On the other hand, when low $V_{GS}$/high $V_{DS}$ stress is applied, it was found that holes are uniformly trapped into the etch stopper and electrons are locally trapped into the gate insulator simultaneously. During a recovery after the high $V_{GS}$/low $V_{DS}$ stress, the trapped electrons were detrapped from the gate insulator. In the case of recovery after the low $V_{GS}$/high $V_{DS}$ stress, it was observed that the electrons in the gate insulator diffuse to a direction toward the source electrode and the holes were detrapped to out of the etch stopper. Also, we found that the potential profile in the a-IGZO bottom-gate TFT becomes complicatedly modulated during the positive $V_{GS}/V_{DS}$ stress and the recovery causing various threshold voltages and subthreshold swings under various read-out conditions, and this modulation needs to be fully considered in the design of oxide TFT-based active matrix organic light emitting diode display backplane.

• 자동차안전학회지
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• 제13권1호
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• pp.26-30
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• 2021

K-city is an experimental area for developing self-driving cars. V2X communications such as WAVE, C-V2X and 5G are an essential technology for autonomous driving above level 4. In this paper, the research on the V2V communication environment was carried out through BSM receiving level analysis on the driving route in K-city. A stationary vehicle communicated with a test vehicle moving along urban area and suburban road in two different scenarios. The communication range and receiving levels obtained from this study will be used to develop and verify various safety scenarios using V2V communication within K-city in the future.

• Korean Journal of Mathematics
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• 제30권2호
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• pp.391-402
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• 2022

For a given graph G = (V, E), a dominating set is a subset V' of the vertex set V so that each vertex in V ＼ V' is adjacent to a vertex in V'. The minimum cardinality of a dominating set of G is called the domination number of G and is denoted by γ(G). For an integer k ≥ 1, the k-th power G^k of a graph G with V (G^k) = V (G) for which uv ∈ E(G^k) if and only if 1 ≤ d_G(u, v) ≤ k. Note that G² is the square graph of a graph G. In this paper, we obtain some tight bounds for the sum of the domination numbers of a graph and its square graph in terms of the order, order and size, and maximum degree of the graph G. Also, we characterize such extremal graphs.