• Analytical Science and Technology
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• v.5 no.1
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• pp.57-61
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• 1992

For the neutron spectrum measurement, $^6Li$ neutron spectrometer system is installed. The characteristic of the $^6Li$ detector are investigated using a $^{137}Cs$ and $^{207}Bi$ point source, and the neutron capture peaks and the pulse height spectrum using an $^{214}Am-Be$ neutron source are measured. Furthermore, the pulse height spectrum for the irradiation time variation from the (214)^Am-Be neutron source, and for the distance variation between detector and source, and the threshold variation of discriminator are measured.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.9-18
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• 2011

In this study the optimal volume for non-point source control retention is estimated considering spatio-temporal variation of land surface. The 3-parameter mixed exponential probability density function is used to represent the statistical properties of rainfall events, and NRCS-CN method is applied as rainfall-runoff transformation. The catchment drainage area is divided into individual $30m{\times}30m$ cells, and runoff curve number is estimated at each cell. Using the derived probability density function theory, the stormwater probability density function at each cell is derived from the rainfall probability density function and NRCS-CN rainfall-runoff transformation. Considering the antecedent soil moisture condition at each cell and the spatial variation of CN value at the whole catchment drainage area, the ensemble stormwater capture curve is established to estimate the optimal volume for an non-point source control retention. The comparison between spatio-temporally varied land surface and constant land surface is presented as a case study for a urban drainage area.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.582-584
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• 2007

In order to improve the accuracy of simulated results, new UV source was designed. Previously the optical simulation was performed with the symmetric planar UV source. To design new UV source, UV distribution from the plasma fluid code was implanted to the 3-dimensional optical code to generate the visible light distribution. The results from planar UV source and new UV source were compared with the ICCD (Intensified CCD) image in real PDP cell and analyzed the variation of geometries and optical properties.

• Science of Emotion and Sensibility
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• v.5 no.3
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• pp.29-34
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• 2002

This study aimed to investigate the effect of design factors of woven textiles on the consumer's sensibility and emotion. 60 textile design pictures and 18 adjectives were prepared to get responses from 512 adult subjects. Textiles designs were analyzed into 9 design factors, such as, motif source, motif-background ratio, motif interpretation, motif arrangement, motif variation, motif articulation, hue contrast, value contrast, and chroma contrast. The results are followings: 1) The design factors of textiles were connected to other design factors, for example, the type of motif interpretation determined the type of chroma contrast, motif source, the ratio, and chroma contrast significantly. 2) The correlational coefficients of the ratio, motif variation, chroma contrast, hue contrast, articulation, and value contrast were positively signed significantly. 3) Consumer's sensibility was changed in urban, natural, graceful, mannish, young, dynamic, new, modem and etc, as the textile designs were changed in motif source, arrangement, hue contrast and etc.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.61-67
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• 2006

We developed a constant current source which is insensitive to threshold voltage variation caused by irregular grain boundary distribution in polycrystalline silicon. The proposed current source has superior saturation characteristics over wide range of input voltages as well as small current error compared to the previously reported Vth compensated sources. We measured the circuit performance and error in current due to parameter variation by using HSPICE.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.393-396
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• 1990

This paper represented constant voltage power source equipment using voltage fed inverter. This system drived syncronizing power source, charged battery connected to DC side, and constantly maintained regardless of power source voltage variation and load variation. Output made good wave with PWM method and we proved stabile constant voltage output when AC power source is failure.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.180-181
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• 2017

Recently as distributed source has increased, the distribution system has changed from unidirectional power flow to bi-directional power flow. This power flow causes the PCC voltage variation, which can adversely affect voltage sensitive loads. In this paper, the relation between the active power, reactive power and PCC voltage of the distributed source is analyzed, and the PCC voltage control scheme by reactive power compensation is proposed in the distributed source itself. In addition, limitations and conditions according to the standard for interconnecting distributed resources are specified and verified through simulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.8
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• pp.725-734
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• 2000

The objective of this paper is to investigate the thermal properties of TMA clathrate applicable to cold storage system for building air-conditioning. Especially, the test tube experiments are peformed by comparing and analyzing the temperature of phase change, specific heat and subcooling characteristic according to the variation of concentrations and temperature of heat source in TMA clathrate. The results are summarized as follows; 1) temperature of phase change is dropped as the temperature of heat source is lower, 2) the effect of subcooling suppression with about $9.3^{\circ}C$ is confirmed when the temperature of heat source is $-10^{\circ}C$ in case of 30wt%, while the temperature of subcooling is about $0^{\circ}C$ when the temperature of heat source is $-15^{\circ}C$ in case of 25, 29wt% and 30wt% . Thus, the effect of subcooling suppression is greater as the temperature of heat source is lower. Additionally, the concentrative study is needed on mass concentration causing the phase change without subcooling phenomenon when the temperature of heat source is $-15^{\circ}C$ Thus, it is concluded that TMA clathrate has proper properties as the cold storage medium for building air-conditioning.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.29-38
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• 2013

In this paper, the illumination performances of three freeform lenses optimally designed for a point source were investigated for several LEDs with different source sizes, and also the tolerance characteristics of the lenses were analyzed. For comparison, two lenses with different sizes were designed with a divergent illumination model, and the last one was done with an overlapped illumination model. As the LED source size increased, the illuminance uniformity decreased more strongly, and the influence of a source misalignment on illumination performance became insignificant. However, the variation of LED radiation characteristics had strong effect on the illumination performance, irrespective of LED source size. Even though the lens based on a divergent illumination model showed superior performance compared to the lens based on an overlapped illumination model, the latter was less sensitive to the variation of LED radiation characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.322-332
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• 2013

Conventional single-phase series quasi Z-source voltage compensator can not compensate for voltage sag less than 50% that frequently occurs in the industrial field. In this study, single-phase series quasi Z-source voltage sag-swell compensator which can compensate the voltage variation of entire range is proposed. The proposed system is composed of two quasi Z-source AC-AC converters connected in series with output terminal stage. Voltage sag less than 50% could be compensated by the intersection switching control of the upper converter duty ratio and of the upper converter duty ratio. Also the compensation voltage and its flowchart for each compensation mode are presented for entire sag-swell region. To confirm the validity of the proposed system, a DSP(DSP28335) controlled experimental system was manufactured. As a result, the proposed system could compensate for the voltage sag/swell of 20% and 60%. Finally, voltage compensation factor and THD(Total Harmonic Distortion) according to voltage variation and load change were measured, and voltage quality shows a good results.