• 동아시아식생활학회지
• /
• 제7권2호
• /
• pp.211-220
• /
• 1997

This study was investigated about preparation of ice at home and developing points which met consumer's demand that was focused on auto icemaker. According to purposive quota sampling method, residences in Seoul and Kyunggi-do area were selected and interviewed by trained interviewer at August 1995. The results were as follows: 66.3% of respondent usually prepared ice in ice-making container of refrigerator and used when they needed. 85% of them used ice in summer and seldomly used in other seasons. Boiling water with barley was major drinking water(45.6%), and broiled or purified tap water was used to make ice(38.6%) commonly. Numbers of ice-making container were two(66.0%). Above 50% of respondents replied that they felt off-flavor in ice usually. After felt off-flavor, 54.7% of respondent threw away the ice, some of them used off-flavored ice after treatment to washing with water. 64.9% of respondents thought that the origins of off-flavor was the flavor of refrigerator itself. The consumer's expectation of developing points were as follows. The most priority of developing points was to make ice quickly, the next was to develop auto ice maker and ice storage container, to make different size of ice. Less expected points were to make more clear ice and large volume of ice in one time. The recognition about auto ice maker was slightly low(35% of respondents), but 67% of them wanted to develop auto ice maker.

• KSBB Journal
• /
• 제8권4호
• /
• pp.328-335
• /
• 1993

고정화 효소를 이용하여 콜레스테롤을 신속, 정확 하게 측정할 수 있는 Flow injection analysis(FIA) 시스댐을 개발하였다. 콜레스테롤 산화효소와 콜레 스테롤 에스테르 가수분해효소를 cantrall어 pore g glass과 glutaraldehyde를 사용해 얻어진 고정화 효 소를, 유리관에 충진해 얻어진 컬럼은 약 3-5 I. U. 의 활성을 나타내였다. 백금을 이용해 구성된 전극 은 +600mV에서 효소반응 결과 생성된 과산화수소 에 대해 특이적으로 응답하였다. 구성되어진 FIA시 스템의 분석능을 향상시키기 위하여 시료량, 캐리어 용액의 유속과 조성 풍의 변화에 따른 응당올 조사 하였다. 최적화된 운영조건하에서 유리 콜레스테롤 과 콜레스테롤 에스테르 표준용액에 대한 응답은 각 각 60, 400mg/ml까지 선형성(r=0.994 빛 0.998) 을 나타내였다. 모든 시료의 분석은 정확, 정밀( <2. 5 5%)한 것으로 조사되었다. 시간당 23회의 분석이 가능하였고, 500회의 간혈분석 후에 응답감도가 약 반으로 감소하였다.

• 대한기계학회논문집B
• /
• 제35권8호
• /
• pp.763-771
• /
• 2011

본 연구에서는 환기용 축류송풍기에 대하여 효율을 목적함수로 하는 수치최적설계를 수행하였다. 유동해석은 삼차원 Reynolds-averaged Navier-Stokes(RANS) 방정식을 통하여 이뤄졌으며, 난류모델로는 Shear Stress Transport 모델을 사용하였다. 최적설계를 위한 설계변수로는 허브비, 날개의 중간 및 팁 스팬에서의 엇갈림각을 사용하였다. 실험계획법으로 라틴하이퍼큐브 샘플링 방법을 사용하여 설계영역 내에서 25개의 실험점을 추출하였다. 최적설계기법인 가중평균대리모델과 삼차원 RANS 해석을 결합하여 수치최적설계를 수행하였으며, 가중평균대리모델로는 WTA1, WTA2 및 WTA3 모델을 사용하였다. 수치 최적설계에 의해 얻어진 최적형상들의 성능을 기준형상과 비교하였으며, 성능이 가장 좋은 모델에 대하여 기준형상과의 내부유동장 비교 및 분석을 통해 성능이 향상된 원인을 규명하였다.

• 한국환경보건학회지
• /
• 제26권2호
• /
• pp.34-40
• /
• 2000

The purpose of this study was to investigate the seasonal variation of PAHs and to estimate their source characteristics in Taegu area. To do this, four sampling sites were selected to represent an industrial, a traffic, a traffic & residential, and a residential area in Taegu. Total of 72 samples had been collected from January, 1999 to September, 1999 on glass micro fiber filters by high volume air sampler. The PAHs in the total suspended particulate were extracted by a soxhlet process with dichloromethane and analyzed by GC/MSD, GC/FID. A statistical analysis was performed for the PAHs data set using a principal component analysis to derive important factor inherent in the interactions among the variables. The specific conclusions of this research are: 1) There was a significant seasonal and local variation in the atmospheric concentration of PAHs. The seasonal variation is winter>spring>Fall>summer, and the local variation is industrial>traffic>graffic & residential>residential area. 2) To evaluate the correlation between a measured PAHs and other affecting factors such as air pollutant concentration and meterological data, statistical analysis was performed. PAHs and other affecting factors such as air pollutant concentration and meterological data, statistical analysis was performed. PAHs have negative correlation with temperature (r=-0.593, p<0.05), radiation(r=-0.535, p<0.05), and O3(r=-0.719, p<0.05), but have positive correlation with NO(r=0.615, p<0.05) 3)Finally, multivariate analysis was performed for the PAHs dat set to identify and to estimate the source contributions of PAHs. According to results of statistical analysis, it could be identifies as three factors such as vehicular/gasoline, vehicular/diesel, and combustion in Taegu area.

• 전기학회논문지
• /
• 제66권2호
• /
• pp.328-338
• /
• 2017

In this paper, a zero torque control scheme adopting current sharing function (CSF) used in integrated Switched Reluctance Motor (SRM) drive with DC battery charger is proposed. The proposed control scheme is able to achieve the keeping position (KP), zero torque (ZT) and power factor correction (PFC) at the same time with a simple novel current sharing function algorithm. The proposed CSF makes the proper reference for each phase windings of SRM to satisfy the total charging current of the battery with zero torque output to hold still position with power factor correction, and the copper loss minimization during of battery charging is also achieved during this process. Based on these, CSFs can be used without any recalculation of the optimal current at every sampling time. In this proposed integrated battery charger system, the cost effective, volume and weight reduction and power enlargement is realized by function multiplexing of the motor winding and asymmetric SR converter. By using the phase winding as large inductors for charging process, and taking the asymmetric SR converter as an interleaved converter with boost mode operation, the EV can be charged effectively and successfully with minimum integral system. In this integral system, there is a position sliding mode controller used to overcome any uncertainty such as mutual inductance or DC offset current sensor. Power factor correction and voltage adaption are obtained with three-phase buck type converter (or current source rectifier) that is cascaded with conventional SRM, one for wide input and output voltage range. The practicability is validated by the simulation and experimental results by using a laboratory 3-hp SRM setup based on TI TMS320F28335 platform.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
• /
• pp.587-592
• /
• 2002

A new digital correlator fur an airborne synthetic aperture radiometer was designed in order to replace the conventional analog correlator unit which will become very complicated while the number of channels is increasing. The digital correlator uses digital IQ demodulator instead of the intermediate frequency (IF) phase shifter to make the correlation processing performed digitally at base band instead of analogly at IF. This technique has been applied to the digital receiver in softradio. The down-converted IF signals from each pair of receiver channels become low rate base-band digital signals after under-sampled, Digitally Down-Converted (DDC), decimated and filtered by FIR filters. The digital signals are further processed by two digital multipliers (complex correlation), the products are integrated by the integrators and finally the outputs from the integrators compose of the real part and the imaginary part of a sample of the visibility function. This design is tested by comparing the results from digital correlators and that from analog correlators. They are agreed with each other very well. Due to the fact that the digital correlators are realized with the help of Analog-Digital Converter (ADC) chips and the FPGA technology, the realized volume, mass, power consumption and complexity turned out to be greatly reduced compared with that of the analog correlators. Simulations show that the resolution of ADC has an influence on the synthesized antenna patterns, but this can be neglected if more than 2bit is used.

• 한국산학기술학회논문지
• /
• 제17권9호
• /
• pp.641-646
• /
• 2016

화석 연료의 연소 과정에서 발생하는 그을음 입자의 형상은 작은 구형입자들이 군집체를 이루고 있는 프랙탈 형상을 하고 있기에 기존 Rayleigh나 Mie 탄성 광 산란 이론으로 분석하는 것에는 한계가 있다. 본 논문에서는 Rayleigh-Debye Gans(RDG) 산란 이론을 적용하여 프랙탈 차원을 가지는 미세 입자의 형상을 효과적으로 해석할 수 있는 과정을 자세히 묘사하였다. 이소옥탄 확산 화염에서 발생하는 그을음 입자를 열 영동 채취법을 이용하여 채집한 후, 투과전자현미경을 이용하여 그을음 입자의 형상을 관찰하였다. RDG 산란 이론을 적용하여, 그을음 입자의 프랙탈 형상을 조사 하였고, 그을음 개별 입자의 직경, 입자 수밀도 및 부피 분율을 산출하였다. 이러한 결과들은 그을음의 성장 과정에서는 뚜렷한 증감 경향을 보이진 않았으나, 그을음 산화 과정에선 전부 뚜렷하게 감소하는 경향을 보였다. 본 연구에서 RDG 산란 이론을 이용하여 도출한 그을음 군칩체의 프랙탈 차원은 약 1.82로 이는 기존의 유사연구 결과와 동일하며, 화석연료의 종류에 상관없이 생성된 모든 그을음 입자에 동일한 값을 갖는 것으로 사료된다.

• Journal of Radiation Protection and Research
• /
• 제11권2호
• /
• pp.91-103
• /
• 1986

가압 경수로형 원자로에서 발생하는 증발기 저부 폐액에서의 Cs-137의 용출에 대한 실험을 수행하였다. IAEA에 의해 제안된 용출실험 방법에 근거를 두고, ANS 방법의 일부를 채용하였다. 용출에 영향을 미치는 여러 인자들로서, 시료채취방법, 양생온도, 양생기간, 용출액 온도, Vermiculite 첨가와 체적 대 표면적비 등이 고려되었다. 준 무한 격판(Semi-infinite Slab)에 대한 확산 모델은 4주간 경화된 시료의 실험치와 좋은 일치를 보이고 있다. 4주간 $25^{\circ}C$에서 양생된 시료의 표면적 확산 계수는 $1.20{\sim}1.47{\times}10^{-11}cm^2/sec$가 됨을 확인했으며, 이 계수에 의해 Cs-137의 장기 용출을 예측을 유한 격판 근사(Finite-slab Approximation) 방법을 이용하여 수행하였다. 또한, 계산 결과로부터 Cs-137은 용출 개시후 약 25년이 되면 초기량의 0.66%인 최대치가 되며 100년 후에는 약 0.25%가 잔류한다.

• 한국산업보건학회지
• /
• 제31권4호
• /
• pp.331-341
• /
• 2021

Objectives: The aim of this study was to evaluate the concentrations and relationships of coarse particles with a diameter of 10 ㎛ (PM₁₀) with endotoxins according to the time of measurement in windowless poultry houses. Methods: In this study, measurement was performed on ten windowless poultry houses with a vertically integrated system from July to November. PM₁₀ was measured using personal environmental monitors and polytetrafluoroethylene (PTFE) filters with a 4 L/min-calibrated pump in selected sampling locations (two near the door and two near an exhaust fan). The endotoxin on PTFE filter was analyzed by the LAL turbidimetric method. Results: The range of geometric mean concentrations of PM₁₀ and endotoxins for each of the 38 samples were 0.12-3.30 mg/m³ and 11.9-3553.66 EU/m³, respectively. PM₁₀ and endotoxin concentrations varied by farm, increasing with the decrease in ventilation. The range of the coefficient of determination between PM₁₀ and endotoxin was 0.0009-0.9249. As the atmospheric temperature decreased, it was confirmed that the concentrations of PM₁₀ and endotoxin increased because the volume of ventilation was decreased. Conclusions: Endotoxins were more affected by time of measurement and ventilation than PM₁₀, which means that endotoxins could be an important indicator for intervention programs for improvement of indoor environments.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 1998년도 학술발표회 논문집
• /
• pp.3-3
• /
• 1998

In this pressentation it is argued that the heterogeneity of a hydrologic attribute which may seem to be nonstationary at one scale, may become stationary at a larger scale. The fundamental reason for transformation from nonstationarity to stationarity whith the increase in scale is the phenomenon of coarse-graining of the hydrologic processes with increasing scale. Due to the phenomenon of aliasing, a particular scale hydrologic process heterogeneity which is observed as a nonstationary process at that scale, may be observed as a stationary process at a higher(larger) scale whose size is bigger than the stationary extent of the lower scale heterogeneity. As one goes through a hierarchical sequence of larger and larger scales for observations, one would eliminate nonstationarities which emerge at some lower scales at the expense of losing information on the high frequency fluctuations of the lower scale heterogeneities which will no longer be observed at the larger sampling scales. We call this phenimenon as the "coarse-graining in hydrologic observations". In this presentation, it is also argued that by the coarse-graining of hydrologic processes due to the averaging and aliasing operations at increasing scales, the conservation laws corresponging to these scales may still be quite parsimonious, and need not be more complicated as the scales get larger. It is shown that shen a higher(larger) scale process is formed by averaging a lower(smaller) scale process in time or space, the high frequency components of the lower scale process will be eliminated by the averaging operation. Thereby, the resuliiting average hydrologic dynamics, free from the effects of the high frequency components of the lower scale process, can still be quite simple in form. This is demonstrated by means of some recent upscaling work on the solute teansport conservation equation for hetergeneous aquifers. By means of this solute transport example, it is also shown that for the ensemble average form of a hydrologic conservation equation to be equivalent to its volume-average form at any scale, the parameter functions of that conservation equation at the immediately lower scale must be ergodic.