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Evaluation of quality index of salted Korean cabbage in the short-term distribution system
정영배,송혜연,박상언,천호현,한응수,정영배 한국식품저장유통학회 2017 한국식품저장유통학회지 Vol.24 No.1
The aim of this study was to provide the quality index of salted Korean cabbage in a short-term distribution system. Salted Korean cabbages were packaged with or without 2% salt water, and then distributed in a conventional system (CVS) and a cold-chain system (CCS) for 6 h. The material temperature of samples with and without salt water gradually increased to 19.57℃ and 19.43℃ in a CVS, respectively and to 10.73℃ and 12.90℃ in a CCS, respectively. Salinity of the materials in a CCS did not change, whereas salinities of the materials in a CVS were 1.2 and 1.7 fold higher, respectively. Also, a slight increase in acidity was observed in both packaging materials in a CCS. In the case of a CVS, total aerobic bacteria and lactic acid bacteria increased to 7.62 log CFU/g and 6.77 log CFU/g in the materials with salt water, respectively, whereas the number of total aerobic bacteria and lactic acid bacteria ranged between 5.62-5.85 log CFU/g and 4.33-4.83 log CFU/g in the materials without salt water, respectively. However, significant microbial changes were not observed in a CCS as distribution time increased. CCS with salt water packaging was effective in achieving microbial control and maintaining physicochemical quality. Salinity, aerobic bacteria, and lactic acid bacteria can be useful as quality indices for a CVS, and acidity can be useful as quality index for a CCS.
정영배,이승호,오혁준,전태준,Jung, Young-Bae,Lee, Seung-Ho,Oh, Hyeok-Jun,Jeon, Tae-Joon 한국전기전자학회 2012 전기전자학회논문지 Vol.16 No.3
본 논문에서는 비접촉식 근거리 무선통신 방식인 NFC(Near field communications)용 안테나에 있어서, 성능 최적화를 위하여 폭 넓게 사용하고 있는 전자기 흡수체에 따른 안테나의 전기적 성능변화를 분석한다. 다양한 투자율을 갖는 흡수체를 이용하여, 해당 흡수체 적용에 따른 안테나성능 변화를 실험을 통하여 확인하고, 흡수체가 NFC안테나의 성능변화에 미치는 영향을 실험적으로 분석하는 방안을 제시한다. In this paper, we analyze the antenna performance variation by the ferrite absorbers which are widely used to optimize the antenna performance in near-field communications(NFC). Using various commercial absorbers, it was confirmed that the absorbers affect the electric performance of NFC antenna, and how to experimentally analyze the electrical influence of the absorbers in NFC antennas is proposed.
정영배,Jung, Young-Bae 한국전기전자학회 2012 전기전자학회논문지 Vol.16 No.3
본 논문에서는 증폭기의 온도에 따른 균일한 출력특성을 구현하기 위한 개선된 보상특성을 갖는 증폭기용 온도보상회로를 제안한다. 제안된 온도보상회로는 직렬로 연결된 2개의 브랜치라인(Branchline) 결합기와 결합기 사이에 위치한 2개의 다이오드로 구성된다. 그리고, 회로의 주변온도에 따라서 저항값이 반비례하는 특서을 갖는 써미스터(Thermistor)와 써미스터를 포함하는 오피엠프(Operational amplifier, OP-Amp.)회로로 다이오드의 동작 특성을 조정함으로써 기존의 온도보상회로에 비하여 보다 효율적인 보상특성을 갖도록 설계하였다. This paper introduces a thermal compensation circuit with improved compensation characteristic for amplifiers to provide stable output power regardless environmental temperature. The proposed thermal compensation circuit is composed of two branchline couplers having two diodes between them. And, the thermistor whose resistance varies significantly with temperature inversely and a operational amplifiers, so called as OP-amp, control the diodes in the compensations circuit to realize more effective thermal compendation characteristic compared with conventional circuit.
수치해석을 통한 소형풍력 블레이드(NACA-4418)에 대한 풍특성 분석
정영배 경상대학교 농업생명과학연구원 2016 농업생명과학연구 Vol.50 No.3
This study aims to observe the wind load characteristics around two-dimensional rotor blade of small wind turbine under high wind speed. The CFD analysis on the blade shape of NACA-4418 is performed to understand the wind load(i.e., drag and lift coefficient). In the results, the drag and lift coefficient were estimated to be 0.013, 0.44, respectively, at the wind speed 35m/s(wind speed at the height of wind tower, z=70m) and angle of attack 3°. By using the lift, drag coefficient and the appropriate assumption of the blade length, the number of blade and the tip speed ratio(TSR), the proper blade shape was obtained. On the base of this basic study, various conditions for Reynolds number and aerodynamic analysis including angle of attack according to parametric test need to study more in the future. Also assessment for the blade need to study safety on wind pressure coefficient and distribution according to wind characteristics.
A Compact Active Channel Module Design for Active Phased Array Antenna System
정영배 한국전기전자학회 2013 전기전자학회논문지 Vol.17 No.4
This paper introduces the T/RX combined compact active channel module which is a key unit of the active phased array antenna(APAA) system. This module is mainly compoased of two parts for TX and RX fabricated on both sides of the active module for size reduction. The TX-part is primarily composed of a 3-stage amplifier, a microstrip phase shifter, a thermal compensation and a power detection circuit. The RX-part is composed of LNAs a microstrip phase shifter and BPFs for TX power rejection. Using the proposed design structure we can realized a compact active channel module having high performance.
CFD에 의한 건물 외피 풍압분포에 관한 수치적 예측과 적용에 관한 연구
정영배,하영철 한국풍공학회 2008 한국풍공학회지 Vol.12 No.2
The simulation for wind pressure coefficients using CFD was carried out as a useful tool. According to present project, this paper presents the results of application and numerical prediction of wind pressure distribution and coefficient over building cladding. The analysis of wind pressure assessment due to wind-resistant design and wind effect to surrounding buildings is important to building cladding. This paper simulates the wind pressure distribution to the building and wind flow pattern around the building cladding, and shows the usability of CFD analysis to design process of building. A Navier-Stokes-Solver with Quick spatial discretization scheme and RNG k- turbulence model has been applied to the computation of the three dimensional turbulent flow.