• Nuclear Engineering and Technology
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• 제35권6호
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• pp.523-528
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• 2003

The efficiencies of single escape and double escape peaks were calculated by using Monte Carlo method and compared with measured efficiencies. The efficiency was obtained from the area ratio of escape peak to full energy absorption peak and the full energy absorption peak efficiency. For the escape peak interfered with other $\gamma-ray$ peaks, the net area was obtained by area correction. The GEANT code developed in CERN was used for the Monte Carlo calculation. The calculated efficiencies of the escape peaks agreed with the measurement within $12\%$.

• Geomechanics and Engineering
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• 제28권3호
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• pp.209-224
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• 2022

In this study, the numerical analysis model of π-beam explosion is established to compare and analyze the failure modes of the π-beam under the action of explosive loads, thus verifying the accuracy of the numerical model. Then, based on the numerical analysis of different protection forms of π beams under explosive loads, the peak pressure of π beam under different protection conditions, the law of structural energy consumption, the damage pattern of the π beam after protection, and the protection efficiency of different protective layers was studied. The testing results indicate that the pressure peak of π beam is relatively small under the combined protection of steel plate and aluminum foam, and the peak value of pressure decays quickly along the beam longitudinal. Besides, as the longitudinal distance increases, the pressure peak attenuates most heavily on the roof's explosion-facing surface. Meanwhile, the combined protective layer has a strong energy consumption capacity, the energy consumed accounts for 90% of the three parts of the π beam (concrete, steel, and protective layer). The damaged area of π beam is relatively small under the combined protection of steel plate and aluminum foam. We also calculate the protection efficiency of π beams under different protection conditions using the maximum spalling area of concrete. The results show that the protective efficiency of the combined protective layer is 45%, demonstrating a relatively good protective ability.

• 한국전기전자재료학회논문지
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• 제14권11호
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• pp.922-927
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• 2001

Single-layer green ELs was fabricated with using molecularly-dispersed Bu-PBD into poly-N-vinylcarbazole(PVK) which has low operating voltage and high quantum efficiency. A EL cell structure of glass substrate/indium-tin-oxide/PVK:Bu-PBD:C6(∼ 100nm)/Ca(20nm)/Al(20nm) was employed with variable doping concentration. The keys to obtain high quantum efficiency was excellent film forming capability of molecularly dispersed into PVK and appropriate combination of cathode for avoiding exciplex. We obtained the turn-on voltage of 4.2V and quantum efficiency of 0.52% at 0.lmol% of C6 concentration which has been improved about a factor of 50 in comparison with the undoped cell. The PL peak wavelengths wouldn\`t be turned by changing the concentration of the C6 dopant. Green EL emission peak and FWHM were 520nm and 70nm respectively. PL emission peak was obtained at 495nm.

• 한국방사선학회논문지
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• 제17권2호
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• pp.175-184
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• 2023

검출기의 실제 모양과 제조사에서 제공한 데이터를 기준으로 Penelope simulation을 통해 검출기 모양을 구현하며 측정치에서 얻은 효율을 기준으로 하여 적합한 사층 두께에 적용하였다. 검출기의 simulation 된 전체에너지피크 효율 채널수와 crystal의 Outside contact layer가 전체에너지피크 효율에 미치는 영향을 결정 하기위한 효율 계산은 Penelope Code를 사용하여 0.3, 0.5, 0.7, 1.0, 1.2 ,1.4 mm의 다양한 사층 두께에 대해 수행하였다. 외부 접촉 사층 두께가 5배 증가하였을 때, 59.50 keV의 경우 전체에너지피크 효율이 약 36% 감소하였으며, 1836.01 keV 경우 10% 감소하였다. 또한 10배 증가할수록 59.54 keV의 경우 FEP 효율이 약 20% 감소하였으며, 1836.01 keV 경우 7% 감소하였음을 확인하였다. Penelope simulation된 전체에너지피크 효율 채널은 사층 증가에 따라 기하급수적으로 감소한다. 또한, 총 효과 곡선은 0.3 - 1.4 mm 사층 두께 영역에서 3.5% 미만의 상대적 차이로 잘 일치함을 확인하였다. 그러나 비균질 사층이 몬테카를로 모델에서 여전히 매개변수라는 것을 알 수 있었다.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.1847-1853
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• 2014

이동통신 시스템의 OFDMA 방식은 신호에 대한 PAPR(Peak to Average Power Ratio) 값의 증가를 가져왔다. 이동통신 시스템 전력 소모의 대부분을 차지하는 전력 증폭기에 대한 효율 개선은 매우 중요한 핵심 기술이다. 전력 증폭기의 선형 특성 개선을 위해 디지털전치왜곡 기술을 사용하였으며, 전력 증폭기의 효율 개선을 위해 비대칭 도허티(Asymmetric Doherty) 방식을 사용하였다. 본 논문에서는 기존 비대칭 도허티 구조와 다른 새로운 구조의 비대칭 도허티 구조를 제안하였다. 제안하는 새로운 구조의 비대칭 도허티 방식에서는 전력 증폭기 구동단을 주경로와 첨두경로로 분리하였으며, 위상 변환기를 이용하여 도허티 증폭기의 전력 결합 특성을 개선하였다. 또한 구동단 첨두 증폭기 gate bais에 대한 포락선 추적 기술을 적용하여 효율을 개선하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.694-697
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• 2007

We demonstrate the use of screen printing in the fabrication of highly efficient phosphorescent polymer organic-light-emitting devices (OLEDs) based on a green-emitting $Ir(ppy)_3$ and a host polymer PVK. We incorporate PBD in the polymer host as an electron-transporting dopant and ${\alpha}-NPD$ as a hole transporting dopant. The best screen printed single-layer device exhibits very high peak luminous efficiency of 63 cd/A at a relatively high operating voltage of 17.1 V at the luminance of $650\;cd/m^2$. We observed the highest luminance of $21,000\;Cd/m^2$ at 35V. Due to the high operating voltage, despite of the high peak luminous efficiency the peak power efficiency was found to be 12.2 lm/W at the luminance of $470\;cd/m^2$ (15.9 V).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.720-723
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• 1996

The recent summer power peak crisis has been caused by excessive use of cooling loads at daily peak time in summer. The yearly load shape of KEPCO has gradually became very steep valley. Under this situation, more efficient DSM(Demand Side Management) tools are fully required for summer peak clipping and shaving. In this paper, the KEPCO's Jeju-Do model project for DSM, especially for Demand Controller, is presented. Demand Controller was evaluated to have the very high economical efficiency against the investment in equipment, as compared with another DSM tools. There were some serious problem to apply Demand Controller to many customers in the aspect to synchronization with KEPCO's watthour meter. But these problems have solved by Keyin's new Demand Controller using vision algorithm.

• 한국ITS학회 논문지
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• 제9권2호
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• pp.51-59
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• 2010

본 논문에서는 입력신호의 Peak to Average Power Ratio (PAR) 에 따라 원하는 출력전력 백-오프 (Output Power Back-Off, OPBO) 구간에서 최적의 효율특성을 가지는 반전 타입의 비대칭 도허티 전력증폭기의 설계 방법을 제안하였다. 원하는 OPBO 구간에서 비대칭 도허티 전력증폭기의 최적 효율특성을 얻기 위해 주 증폭기와 피킹 증폭기의 피크 전력비를 결정하였고 피크 전력비에 따른 $90^{\circ}$ 임피던스 변환기의 정확한 임피던스 값을 도출 하였다. 또한 비대칭 도허티 전력증폭기 설계시 최적의 성능을 얻기 위해 오프셋 라인의 길이와 전력 분배비를 계산하였다. 측정결과, 비대칭 도허티 전력증폭기는 CDMA 2000 1x 3-FA 테스트 신호에 대해서 평균 출력 전력 48.7 dBm에서 40%의 전력 효율과 -35 dBc의 인접 채널전력비를 얻었다.

• 환경영향평가
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• 제23권3호
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• pp.169-176
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• 2014

The purpose of this study is to estimate the vibration reduction effect of the borehole which is controlled the vibration propagation in the ground. For this study, we measured the vibration velocity before and after the borehole installation. The results are as follows: The peak particle velocity(PPV) and peak vector sum(PVS) was reduced by the borehole. And also, the deviation of vibration velocity before and after the borehole installation showed large values in longitudinal and vertical component depending on the receive distance, and increased depending on the size of vibration energy. Finally, the vibration isolation efficiency was 25~35 percentage at 1.5m receive distance, and was 4~14 percentage at 3.0m receive distance. It was found that the vibration isolation efficiency was good in small vibration energy, but was not good at long receive distance.

• Nuclear Engineering and Technology
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• 제41권5호
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• pp.723-728
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• 2009

The response property of the CZT detector ($5{\times}5{\times}5\;mm^3$), widely used in photon spectroscopy, was evaluated by considering the charge collection efficiency, which depends on the interaction position of incident radiation, A quantitative analysis of the energy spectra obtained from the CZT detector was also performed to investigate the tail effect at the low energy side of the full energy peak. The collection efficiency of electrons and holes to the two electrodes (i.e., cathode and anode) was calculated from the Hecht equation, and radiation transport analysis was performed by two Monte Carlo codes, Geant4 and MCNPX. The radiation source was assumed to be 59.5 keV gamma rays emitted from a $^{241}Am$ source into the cathode surface of this detector, and the detector was assumed to be biased to 500 V between the two electrodes. Through the comparison of the results between the Geant4 calculation considering the charge collection efficiency and the ideal case from MCNPX, an pronounced difference of 4 keV was found in the full energy peak position. The tail effect at the low energy side of the full energy peak was confirmed to be caused by the collection efficiency of electrons and holes. In more detail, it was shown that the tail height caused by the charge collection efficiency went up to 1000 times the pulse height in the same energy bin at the calculation without considering the charge collection efficiency. It is, therefore, apparent that research considering the charge collection efficiency is necessary in order to properly analyze the characteristics of CZT detectors.