• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.101.1-101.1
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• 2016

Van der Waals (vdW) heterostructures built from two-dimensional layered materials provide an unprecedented opportunity in designing new material systems because the lack of dangling bonds on the vdW surfaces enables the creation of high-quality heterointerfaces without the constraint of atomically precise commensurability. In particular, the ability to build artificial heterostructures, combined with the recent advent of transition metal dichalcogenides, allows the fabrication of unique semiconductor heterostructures in an ultimate thickness limit for fundamental studies as well as novel device applications. In this talk, we will present the characterization of the electronic and optoelectronic properties of atomically thin p-n junctions consisting of vertically stacked WSe2 and MoS2 monolayers. We observed gate-tunable diode-like current rectification and a photovoltaic response across the p-n interface. Unlike conventional bulk p-n junctions, the tunneling-assisted interlayer recombination of the majority carriers is responsible for the tenability of the charge transport and the photovoltaic response. Furthermore, we will discuss the enhanced optoelectronic characteristics in graphene-sandwiched vdW p-n junctions.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.235-240
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• 2005

This paper presents a dual band circularly polarized microstrip patch antenna. The antenna consists of two corner truncated patches implemented in one plane and single feed point. The input signal is directly excited to the patch 2 and the patch 1 is fed from patch 2 by coupling between two patches. The antenna is operated at 900 MHz and 2.45 GHz bands and has the right hand circularly polarized radiation pattern at all. The measured gains of the antenna are 2.95 dBic at 900 MHz band and 4.6 dBic at 2.45 GHz band.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.185-187
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• 2009

본 논문에서는 디밍으로 인한 32W 형광등의 수명특성과 동정을 실험을 통해서 분석하였다. 기존의 형광 램프용 전자식 안정기 내부의 인버터 공진특성을 이용해 주파수를 변환시켜 소비전력을 낮추면서 형광등의 조도를 조정하였다. 조정된 형광등의 안정기를 소비전력의 퍼센트별로 분류해서 조도특성을 위주로 수명의 측정을 실시하였다. 수명특성 실험은 2개월간 실험실 내에 형광등을 설치 할 수 있는 실험대를 제작하였으며 주기적으로 형광등의 주위온도와 조도의 측정을 실시하였다. 본 논문에서 분석한 형광등의 수명특성 결과는 향후 형광등 전용 디밍 전자식 안정기 설계 시 활용 될 수 있을 것이다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.347-348
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• 2008

We investigate the characteristics of a dipole antenna on an artificial magnetic conductor (AMC) constructed of a normal material and a ground plane. We studied how the antenna performance is affected by changes in the dipole length and the distance between the dipole and the ground plane. The relation between the reflection phase of the AMC and the input resistance of the dipole for input impedance matching is also verified.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1117-1122
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• 2006

The PEM type regenerative fuel cell(RFC) for the ground simulator of the regeneration electric power system has been designed, manufactured, and tested. In this paper, the designing and manufacturing procedures of the RFC were presented. Also, the performance test results were showed briefly. The RFC consists of PEM type stack, humidifier, pressure and flow control valve, storage tanks, pump and controller. The performance tests were carried out with stack and system performance tests. The performance targets are more than 50% stack efficiency, 1.5kW stack power, less 400W parasitic power in design condition. Most of the performances required are satisfied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.63-64
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• 2009

The TFTs have been fabricated with 3 different geometry SID electrodes which have the same channel W/L ratio (W/L = 5) due to constant channel resistance, The 3 samples have different channel widths (350, 150, and $25\;{\mu}m$) and channel lengths (70, 30, and $5\;{\mu}m$) by fixed channel W/L ratio simultaneously on one chip for reliable comparisons. Resultant on-current and field effect mobility are proportional to the channel width, while the subthreshold swing is inversely proportional to the channel width mainly due to the change of contact resistance. These results show that the contact resistance strongly affects the device performances and should be considered in the applications.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.482-485
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• 2007

The S-Band SSPA is front-end equipment to transmit both LRIT and HRIT to COMS. To provide the required EIRP, S-Band SSPA is designed to generate maximum 1kW power at its 1dB gain compression point (P1dB). Due to the operation for 24 hours per seven days, the verification on the performance of S-Band SSPA was performed thoroughly. This paper presents that major requirements such as maximum 1kW power, maximum -26dBc of IMD characteristic at 500W output and around -57dBc of coupling factor were verified through proposed test configuration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.747-750
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• 2009

The TFTs have been fabricated with 3 different geometry SID electrodes which have the same channel W/L ratio (W/L = 5) due to constant channel resistance, The 3 samples have different channel widths (350, 150, and 25 ${\mu}m$) and channel lengths (70, 30, and 5 ${\mu}m$) by fixed channel W/L ratio simultaneously on one chip for reliable comparisons. Resultant on-current and field effect mobility are proportional to the channel width, while the subthreshold swing is inversely proportional to the channel width mainly due to the change of contact resistance. These results show that the contact resistance strongly affects the device performances and should be considered in the applications.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.417-420
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• 2002

수중 음향 탐지 시스템에서 빔 형성 기법 및 개별 센서에 대한 정합회로의 설계는 실제 시스템 설계 시 시스템의 성능을 결정하는 중요한 요소이다. 본 논문에서는 이 두 가지 기법을 통합하고 있으면서 일반 사용자들도 쉽게 최적 빔 설계를 통한 가중치를 구하고 또 개별 소자에 대한 센서 임피던스 정합회로를 설계할 수 있도록 해주는 통합 S/W를 구현하였다. 본 프로그램을 이용하여 최적의 가중치를 구하고 그 가중치를 가지는 개별 센서의 정합회로를 일괄적으로 설계할 수 있다. 앞으로도 실제 사용자로부터 의견을 수렴하여 계속 성능을 보완할 예정이며 교육용이나 실제 산업용으로 사용이 가능할 것으로 생각된다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.51-52
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• 2013

Generally, Adiabatic temperature rise and temperature rise rate are reported to increases when placement temperature, W/B and the unit water content is fixed. In this study, properties of adiabatic temperature rise on placement temperature consider the hot weather environments from of W/B 0.29, 0.34, 0.40 was reviewed, the amount of cement on mixing condition of the same W/B and unit water content evaluated on the impact of the adiabatic temperature rise. As a results, the adiabatic temperature rise of concrete is proportionate to binder as well as the cement content under the same unit water content.