• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2091-2093
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• 2005

Five model coils of 6.6kV motor were manufactured with several defects. These stator coils have artificial defects such as void of groundwall insulation, removal of semi-conductive coating and damage of strand insulation. Epoxy-mica coupler(80 pF) was connected to five model coil terminals, respectively The voltage applied to the coils was 3.81kV, 4.76kV, 6.0kV and 6.6kV. Partial discharge(PD) tests performed in the laboratory and shield room. Digital PD detector (PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of model coils were indicated the internal and slot discharges. PD patterns coincide with both PDD and TGA.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2175-2178
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• 2005

During normal machine operation, partial discharge(PD) measurements were performed with turbine generator analyzer(TGA) in five high voltage motors(rated 6.6kV). These high voltage motors were installed with 80pF capacitive couplers at the terminal box. 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). Off-line PD measurements were conducted on five motors. These motors were energized to 3.81kV. The PD levels in pC were measured with a conventional digital PD detector. The comparison of positive to negative PD indicates whether the defect elements of PD are within the insulation or on the insulation surface. Internal discharges were generated in phase A, B and C of COP-B and pulv.-B, in phase B of Pulv. C and in phase C of Pulv.-D motor. Discharge at conductor surface was discovered in phase A of Pulv. D motor. Slot discharges occurred in three phases of Pulv. E motor.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1175-1178
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• 2004

On-line partial discharge(PD) monitoring system has been developed to monitor in operating large motor stator insulations. This system makes use of remote diagnosis techniques for the evaluation of PD activity in the control center of thermal power plant. This system can be remotely accessed via a modem to build database, analyze status and interpret the pattern of PD activity. A personnel computer is generally connected to ten motors to continuous measurement of the PD activity. The test data can be easily interpreted by a maintenance staff. For assessing the condition of stator winding in motors, this system ensures a reliable measurement and accurate estimation. Capacitive couplers used for on-line PD measurement have been 80pF. The maximum PD magnitude(Qmax), PD pattern and normalized quantity number(NQN) were performed by this system.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권4호
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• pp.178-182
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• 2006

Five model coils of 6.6 kV motor were manufactured with several defects. These stator coils have artificial defects such as void of groundwall insulation, removal of semi-conductive coating and damage of strand insulation. Epoxy-mica coupler(80 pF) was connected to five model coil terminals. The voltage applied to the coils was 3.81 kV, 4.76 kV, 6.0 kV and 6.6 kV, respectively. Partial discharge(PD) tests performed in the laboratory and shield room. Digital PD detector(PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of model coils were indicated the internal and slot discharges. PD patterns are consistent with the result of measurement using PDD and TGA instruments. AC breakdown test was performed on five model coils in order to confirm the result of PD measurements. All the failures were located in a line-end coil at the exit from the core slot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1824-1827
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• 2003

During normal machine operation, partial discharge(PD) measurements were performed with turbine generator analyzer(TGA) in two high voltage motors. Two 6.6kV motors were installed with 80pF capacitive couplers at the terminal box. The PD patterns were displayed two dimensional and three dimensional. TGA summarizes each plot with two quantifies such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). Off-line PD measurements were conducted on one 4.16kV motor. The motor was energized to 2.4kV, 3.0kV, 3.5kV and 4.16kV, respectively. The PD levels in pC were measured with a conventional digital PD detector. The comparison of positive to negative PD indicates whether the defect elements of PD are within the insulation or on the insulation surface. Discharge at conductor surface was discovered in No. 1 motor. Internal discharges were generated in phase A, B and C of No. 2 motor, Slot discharges occurred in three phases of No. 3 motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1612-1614
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• 2003

80pF capacitive couplers were connected to six 6.6kV motor model coil terminals. The voltage applied to the coils were 3.81kv, 4.76 kV and 6.6kV, respectively. These stator coils have various types of artificial insulation defects such as large voids, semi-conductive coating damage and strand insulation fault. Digital PD detector(PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in PD were measured with a conventional digital PD detector. Most of the defect mechanism of large motor stator winding can be associated with PD patterns such as internal and slot discharges. PD patterns coincide with PDD and TGA. These instruments have an input bandwidth of 40-400kHz and 0.1-350MHz. Surge testing detects faults in inter-turn winding of high voltage motor model coils.

• 조명전기설비학회논문지
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• 제28권7호
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• pp.41-47
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• 2014

The on-line partial discharge (PD) in stator windings of air-cooled gas turbine (GT) generator (119.2MVA, 13.8kV) is measured and analyzed in this paper. This generator was designed by global vacuum pressure impregnation (VPI). The generator failed two times at top bar (16T) of phase B in the stator slot. Six epoxy-mica capacitors were installed in three phases of GT generator. On-line PD test was performed on GT generator using turbine generator analyzer (TGA). TGA showed that the normalized quantity number (NQN) and the PD magnitude($Q_m$) were high in phase B. Internal discharges were generated in phases A, B and C. The trend analysis of NQN and $Q_m$ value are obtained in order to monitor the insulation condition in GT generator stator windings. Phases A and C were in good condition. But phase B had deteriorated significantly

• 대한전자공학회논문지SP
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• 제40권5호
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• pp.410-416
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• 2003

인접투사 알고리즘(Affine Projection Algorithm: APA)에서 투사 차원은 적응필터 계수갱신에 사용하는 입력 벡터 요소 수이며, 이는 계수갱신을 위해 사용되는 투사 기저의 개수이다. 그리고 투사차원은 적응 필터의 수렴속도와 밀접한 관계가 있으며 알고리즘에서 필요한 계산량을 결정한다. 적응필터가 수렴함에 따라 수렴속도가 감소하게 되므로, 수렴속도를 결정하는 투사차원을 줄일 수 있다. 본 논문에서는 적응필터 계수갱신 시 계수벡터의 변화량을 수렴속도와 연관시켜 인접투사 알고리즘의 투사차원을 조정하는 가변 차원 인접투사 알고리즘(Variable Dimension APA: VDAPA)을 제안한다. 제안한 방법은 적응필터의 수렴정도에 따라 투사 기저 수를 조정함으로써 APA의 계산량을 줄인다. 컴퓨터 모의 실험을 통해 기존의 인접투사 알고리즘 및 NLMS 알고리즘과의 수렴속도, 계산량 면에서 성능을 비교하여 제안한 방법의 우수성을 확인한다.

• Tuberculosis and Respiratory Diseases
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• 제51권6호
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• pp.540-549
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• 2001

연구배경 : 특발성 폐섬유화증 중 통상성 간질성 폐렴(Usual interstitial pneumonia)은 대부분 진행성으로 악화되는 매우 나쁜 질환이다. 조직학적으로 볼 때 상피하에 흩어져서 존재하는 fibroblastic foci에서 콜라겐 합성을 통한 폐 섬유화를 일으키는 것으로 알려져 있다. 이러한 fibroblastic foci와 폐기능을 포함한 임상적 지표 및 예후와의 상관관계를 알아보고자 하였다. 방 법 : 개흉 또는 흉강경을 통한 폐 생겸검사로 진단된 20명(남:여 13:7)을 대상으로 하여 폐 조직에서 fibroblastic foci의 양을 정량화 하였다. 결 과 : 1) Fibroblastic foci 양과, 폐기능검사, 동맥혈가스검사($AaDO_2$) 사이에는 유의한 상관관계가 없었으며, 기관지폐포 세척검사의 세포분획중 호중구 비율과는 의미있는 비례관계(p<0.05)가 있었다. 2) Fibroblastic foci/vol을 0.2를 기준으로 두 그룹으로 나누어 각 그룹간의 생존률, 폐기능검사, 기관판지폐포 세척검사의 세포분획비율의 차이를 비교한 결과 기판지폐포세척액의 호중구비율이 fibroblastic foci가 많은 군에서 의미있게 높았으며(p<0.05), 생존율, 폐기능점사등은 두 군간에 유의한 차이는 없었다. 결 론 : 본 연구에서는 fibroblasic foci가 UIP 환자의 예후 및 질환의 활성도를 나타내주는 지표로는 확실하지 않은 것으로 여겨지며, 추가로 좀더 많은 자료로 분석이 필요할 것으로 여겨진다.

• 대한토목학회논문집
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• 제32권3D호
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• pp.239-245
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• 2012

건설프로젝트가 대형화 복잡화 전문화 되어감에 따라 전문적인 사업관리의 필요성이 증가하고 있다. 따라서 1996년 이후 국내 CM시장이 점진적으로 확대되고 있다. 이러한 CM시장의 증가세에도 불구하고, 국내 전문가들은 CM 제도와 기반이 부족함을 지적하고 있는 실정이다. 따라서 본 논문은 CM시장 활성화를 위한 인과지도를 제시하였다. 그리고 기초관계 균등단위 모델링을 이용하여 CM 시장 규모를 예측하기 위한 시뮬레이션을 수행하였다. 그 결과 CM관련 제도적 규제가 많을수록 CM시장이 위축되는 양상을 나타났으며, 2015년 이후 건설감리시장을 추월하는 것으로 나타났다. 본 논문은 국내 CM시장의 활성화를 위한 제도개선의 필요성과 개선요인의 인과관계에 따른 CM시장의 변화를 전망하는 자료로 활용될 수 있다. 그리고 향후 CM시장 활성화 요인 중 비제도적 요인의 변화를 기준으로 한 CM시장 활성화 방안연구의 기초자료로 활용될 수 있을 것이다.