DC-Sputtering 방법으로 TiN 및 ZrN 코팅한 치과교정용 스테인리스강 선재의 부식 및 기계적 특성

박재준,최한철,고영무,조정현,류아라 대한치과재료학회 2004 대한치과기재학회 학술대회 Vol.2004 No.8

셀룰러 CDMA 기지국에 beamforming 안테나를 적용하기 위한 동작 시뮬레이션 및 성능해석에 관한 연구

박재준,배병재,장태규,Park, Jae-Jun,Bae, Byeong-Jae,Jang, Tae-Gyu 대한전자공학회 2000 電子工學會論文誌-TC (Telecommunications) Vol.37 No.2

본 논문에서는 CDMA 기지국에 선형 어레이 안테나를 적용하고자 할 경우, beamforming(BF) 성능과 관련된 두 가지 주요지표인 주 빔 폭의 좁은 정도를 지칭하는 direction selectivity와 사용자 신호의 방향추정 정확도가 BF의 SINR(Signal to interference and noise ratio) 성능에 미치는 영향과 이들 상호간의 관련성을 해석적으로 유도하였으며, 이를 수신 동작 시뮬레이션을 통하여 확인하였다. BF에 내포된 사용자 방향추정 기능과 간섭 사용자 신호 억제기능에 대하여 이들의 오차가 SINR에 미치는 영향을 구분하여 알아보기 위한 목적으로 방향추정 기능만을 포함한 steering BF 알고리즘과 간섭 사용자 전력을 최소화시키는 기능이 포함된 MVDR(Minimum variance distortionless response) BF 알고리즘을 대상으로 해석 및 동작 시뮬레이션을 수행하였다. 이 과정에 BF 알고리즘의 방향추정 기능에 직접적으로 오차를 유발하는 전파의 공간적 scattering 현상에 대한 모델을 새로이 제시하여 적용하도록 하였다. 본 연구의 결과, 종래의 군사적 목적의 BF와는 달리 셀룰러 CDMA 기지국에 array 안테나를 적용하고자 할 경우는 direction selectivity 및 사용자 방향추정 정확도를 향상시키고자 하는 것이 구현의 경제성 및 오차요인들에 대한 robustness 측면에서는 적합하지 않다는 것을 확인하였다. 이러한 특성은 BF 성능열화에는 크게 영향을 주지 않으면서 복잡도를 최소화하고 오차요인에 대한 robustness 특성을 갖는 경제적인 BF 알고리즘의 구현을 가능케 하여주는 중요한 사실이다. 이에 본 연구에서 제시한 해석의 결과는 셀룰러 CDMA기지국에 대한 BF 알고리즘 개발 및 적용의 설계지표로서 의미가 크다하겠다. This paper presents the analytic derivation of the SINR, when a linear array antenna is accommodated into the cellular CDMA basestation receiver, in relation to the two major performance effecting factors in beamforming(BF) applications, i. e., the direction selectivity, which refers to the narrowness of the mainbeam width, and the direction-of-arrival(DOA) estimation accuracy. The analytically derived results are compared with the operation simulation of the receiver realized with the several BF algorithms and their agreements are confirmed, consequently verifying the correctness of the analysis and the operation simulation. In order to investigate separately the effects of the errors occurring in the direction estimation and in the interference suppression, which are the two major functional components of general BF algorithms, both the algorithms of steering BF and the minimum- variance- distortionless-response(MVDR) BF are applied to the analysis. A signal model to reflect the spatially scattering phenomenon of the RF waves entering into the .:nay antenna, which directly affects on the accuracy of the BF algorithm's direction estimation, is also suggested in this paper and applied to the analysis and the operation simulation. It is confirmed from the results that the enhancement of the direction selectivity of the away antenna is not desirable in view of both the implementation economy and the BF algorithm's robustness to the erroneous factors. Such a trade-off characteristics is significant in the sense that it can be capitalized to obtain an economic means of BF implementation that does not severely deteriorate its performance while ensuring the robustness to the erroneous effects, consequently manifesting the significance of the analysis results of this paper that can be used as a design reference in developing BF algorithms to the cellular CDMA system.

여러종류의 Organoclay에 대한 에폭시-나노콤포지트의 열적, 유전특성에 관한 연구

박재준,Park, Jae-Jun 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.6

Nanostructured materials are attracting increased interest and application. Exciting perspectives may be offered by electrical insulation. Epoxy/Organoclay nanocomposites may find new and upgraded applications in the electrical industry, replacing conventional insulation to provide improved performances in electric power apparatus, e.g, high voltage motor/generator stator winding insulation, dry mold transformer, etc. In the paper work, the electrical and thermal properties of epoxy/organoclay nanocomposites materials were studied. The electrical insulation characteristics were analyzed through the permittivity characteristics. by analyzing the permittivity spectra, it was found that dielectric constant becomes smaller with increase frequency and becomes larger with increase temperature. This indicates restriction of molecular motion and strong bonds at the epoxy/organoclay nanocomposites. The morphology of nanocomposites obtained was examined using TEM and X-ray diffraction. It has been shown that the presence of polar groups leads to an increased gallery distance and partial exfoliation. Nevertheless, full exfoliation of clay platelets has not been achieved.

누설 전류 모니터링에 의한 오손된 고분자 애자에서의 섬락 예지 방법

박재준,송영철 대한전기학회 2004 전기학회논문지C Vol.53 No.7(C)

In this paper, a flashover prediction method using the leakage current in the contaminated EPDM distribution polymer insulator is proposed. The leakage currents on the insulator were measured simultaneously with the different salt fog application such as 25g, 50g, and 75g per liter of deionized water. Then, the measured leakage currents were enveloped and transformed as the CDFS using the Hilbert transform and the level crossing rate, respectively. The obtained CDFS having different gradients(angles) were used as a important factor for the flashover prediction of the contaminated polymer insulator. Thus, the average angle change with an identical salt fog concentration was within a range of 20 degrees, and the average angle change among the different salt fog concentrations was 5 degrees. However, it is hard to be distinguished each other because the gradient differences among the CDFS were very small. So, the new weighting value was defined and used to solve this problem. Through simulation, it is verified that the proposed method has the capability of the flashover prediction.

Kaolin 오손물 누적량 모의실험 및 누설전류변화 특성

박재준,송일근,이재봉,천성남 대한전기학회 2005 전기학회논문지C Vol.54 No.11-C

This study performs a simulation for an accumulation mechanism of contaminants, which were produced in an industrial belt of inland, on the surface of insulators. From the simulation, silicon insulators presented higher accumulation than that of EPDM(Ethylene Propylene Diene Terpolymer : EPDM) insulators on the same distance in the case of the Virgin polymer insulator, and this result presented the same result in the insulator applied in actual fields. In the case of the accumulation test for the Virgin insulator and insulators used in actual fields, it is evident that the Virgin insulator presented more accumulation than that of the insulator used in actual fields. The results can be caused by the generation of LMW (Low Molecular Weight) on the external material of polymer insulators, and the level of the accumulation can be changed according to the degree of the continuous generation of LMW. In order to simulate a certain pollution of an industrial belt, which is located along the coastline, leakage currents were measured by applying the contaminant compulsively that was produced with salts and Kaolin according to the ratio of its weight on the surface of insulators. The more increase in the content of Kaolin pollution, the level of leakage currents on the surface of polymer insulator more increased. In addition, the approaching time to the maximum value of leakage currents presented a nearly constant level regardless of the content of Kaolin. The level of leakage currents significantly decreased according to the passage of time, and the level of leakage currents on the surface maintained a constant level at a specific time regardless of the content of Kaolin.

장내 미생물과 소화기 질환

박재준 대한내과학회 2022 대한내과학회 춘계학술대회 Vol.2022 No.-

표면개질된 나노 알루미나의 에폭시-나노 콤포지트 유전 특성

박재준,Park, Jae-Jun 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.10

The aim of this study is to improve of dielectric properties using epoxy/nano alumina composites with adding glycerol diglycidyl ether (GDE:1,2 g). This paper deals with the effects of dielectric properties(${\epsilon}^{\prime}_r$ and $tan{\delta}$) for epoxy/nano alumina contents (1,3 phr) and GDE addition (1,2 g)composites. 5 kinds specimen were prepared with containing epoxy resins, epoxy nano alumina composites. Average particle size of nano used were 30 nm. The nano alumina used were gamma phase particles of spherical shape. The suppression of epoxy chain motion by addition of nano alumina+GDE decreased dielectric loss and relative permittivity magnitude.

고압전동기 고정자권선 결함 부분방전패턴

박재준,김희동,Park, Jae-Jun,Kim Hee-Dong 한국정보기술전략혁신학회 2004 情報學硏究 Vol.7 No.1

During normal machine operation, partial discharge(PD) measurements were performed with turbine generator analyzer(TGA) in imitation stator winding of high voltage motors. The motor was energized to 4.47kV, 6.67, respectively. Applied voltage to Imitation winding was used two voltage level, 4.47[kV] and 6.67[kV]. Motors having imitation stator winding were installed with 80pF capacitive couplers at the terminal box. Case of PD Pattern regarding applied voltage phase angel, the PD patterns were displayed two dimensional and three dimensional. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). As the result, we could discrimidate using TGA the difference of internal and surface discharge for imitation stator winding. We have used the other technique, in order to feature extraction of faulty signals on stator winding, Daubechies Discrete wavelet transform and Harmonics analysis(FFT) about faulty signals.

웨이블렛변환을 이용한 부분방전 종류의 특징추출에 관한 연구

박재준,Park, Jae-Jun 한국정보기술전략혁신학회 2003 情報學硏究 Vol.6 No.1

In this papers, we proposed the new method in order to diagnosis partial discharge type of transformers. For wavelet transform, Daubechie's filter is used,, we can obtain wavelet coefficients which is used to extract featrue of statistical parameters(maximum value, average value, dispersion, skewness, kurtosis) about high frequency current signal per 3-electrode type(needle-plane electrode, IEC electrode and Void electrode). Also, these coefficients are used to identify signal of internal partial discharge in transformer. As a result, from compare of high frequency current signal amplitude and average value, we are obtained results of IEC electrode> Void electrode> Needle-Plane electrode. Otherwise, in case of skewness and kurtosis, we are obtained results of Void electrode> IEC electrode> Needle-Plane electrode. As improved method in order to diagnosis partial discharge type of transformers, we use neural network.

HF-CT센서를 이용한 고분자애자의 오손특성

박재준,Park, Jae-June 한국정보기술전략혁신학회 2005 情報學硏究 Vol.8 No.4

Investigations of high frequency current transformer(HF-CT) waveform characteristics of the surface leakage on kaolin polluted EPDM polymer insulators have been performed. This work is part of a program aimed at examining the potential for HF-CT waveform characteristics analysis to provide information about the environment contaminants and environment condition of polymer insulators. The investigation reported examined the HF-CT waveform characteristics at high frequencies. The use of high frequency measurements for on-line applications reduces electrical inference. This work was peformed utilizing HF-CT to monitor of surface polluted discharge. It was found that HF-CT waveform frequency spectrum, magnitude depend on importantly the duration of the surface discharge activity.