• Nuclear Engineering and Technology
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• 제38권1호
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• pp.99-108
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• 2006

SNU-RCCS is a water pool type RCCS (Reactor Cavity Cooling System) developed for VHTR (Very High Temperature Reactor) application by SNU (Seoul National University). Since radiation heat transfer is the major process of passive heat removal in a RCCS, it is important to determine the precise emissivity of the reactor vessel. Review studies have used a constant emissivity in the passive heat removal analysis, even though the emissivity depends on many factors such as temperature, surface roughness, oxidation level, wavelength, direction, atmosphere conditions, etc. Therefore, information on the emissivity of a given material in a real RCCS is essential in order to properly analyze the radiation heat transfer in a VHTR. The objectives of this study are to develop a method for compensation of the factors affecting the emissivity measurement using an infrared thermometer and to estimate the true emissivity from the measured emissivity via the developed method, especially in the SNU-RCCS environment. From this viewpoint, we investigated factors such as the attenuation effect of the window, filling gas, and the effect of background radiation on the emissivity measurements. The emissivity of the vessel surface of the SNU-RCCS facility was then measured using a sight tube. The background radiation was subsequently removed from the measured emissivity by solving a simultaneous equation. Finally, the calculated emissivity was compared with the measured emissivity in a separate emissivity measurement device, yielding good agreement with the emissivity increase with vessel temperature in a range of 0.82 to 0.88.

• 경영과학
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• 제22권1호
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• pp.47-66
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• 2005

Online game business has emerged as the most lucrative entertainment Industry, with over 10 million players in South Korea. The popularity of online games can be attributed to the availability of broadband network and the presence of numerous PC Bangs and around the country, which have pushed online games Into the main-stream entertainment culture. The age distribution of online game players is expanding and a variety of new games are under development to target certain age groups. While the interactive entertainment market continues to expand, with many new online game publishers entering the market, relatively little is known about which factors influence online game players' behavioral intentions to play continuously in this area. It appears that in this extremely attractive and growing services segment, academics, as well as practitioners, would benefit from in vestigating the relationships among the players' loyalty, interactivity, the sense of presence and the impacts of several other key game-related constructs. Several types of interaction in on-line games and their relationship with the flow construct are investigated, and the resulting conceptual model is proposed. Based on data collected from online questionnaire survey, the validity of the simultaneous equation model has been tested and interesting conclusions have been developed concerning the relationships between the players' loyalty to the sense of presence, flow, satisfaction and interactions. Other interesting results concerning game development strategy are also provided.

• 기술혁신연구
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• 제12권1호
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• pp.241-269
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• 2004

Online game business has emerged as the most lucrative entertainment industry, with over 10 million players in South Korea. The popularity of online games can be attributed to the availability of broadband network and the presence of numerous PC Bangs and around the country, which have pushed online games into the mainstream entertainment culture. The age distribution of online game players is expanding and a variety of new games are under development to target certain age groups. While the interactive entertainment market continues to expand, with many new online game publishers entering the market, relatively little is known about which factors influence online game players' behavioral intentions to play continuously n this area. It appears that in this extremely attractive and growing services segment, academics, as well as practitioners, would benefit from investigating the relationships among the players' intentions to play, flow, and the impacts of several other key game-related constructs n consumer behavioral intentions. Several types of interaction in on-line games and their relationship with the flow construct are investigated, and the resulting conceptual model is proposed. Based on data collected from online questionnaire survey, the validity of the simultaneous equation model has been tested and interesting conclusions have been developed concerning the relationships between the players' behavioral intentions to play, flow, and interactions. Other interesting results concerning game development strategy are also provided.

• 공학교육연구
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• 제15권5호
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• pp.93-97
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• 2012

Most of ubiquitous computing devices such as stereo camera, ultrasonic sensor based MIT cricket system and other wireless sensor network devices are widely applied to the 2 Dimensional(2D) localization system in today. Because stereo camera cannot estimate the optimal location between moving node and beacon node in Wireless Personal Area Network(WPAN) under Non Line Of Sight(NLOS) environment, it is a great weakness point to the design of the 2D localization system in indoor environment. But the conventional 2D triangulation scheme that is adapted to the MIT cricket system cannot estimate the 3 Dimensional(3D) coordinate values for estimation of the optimal location of the moving node generally. Therefore, the 3D triangulation scheme based on the space segmentation in WPAN is suggested in this paper. The measuring data in the suggested scheme by computer simulation is compared with that of the geographic measuring data in the AutoCAD software system. The average error of coordinates values(x,y,z) of the moving node is calculated to 0.008m by the suggested scheme. From the results, it can be seen that the location correctness of the suggested scheme is very excellent for using the localization system in WPAN.

• 유기물자원화
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• 제24권4호
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• pp.5-9
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• 2016

현대의 집적된 산업 사회에서 자정능력을 초과하여 발생하는 막대한 양의 유기성폐자원은 수질, 토양, 대기 등 총체적인 환경오염을 유발하는 처리 곤란 물질로 전락하였고, 화석연료의 지속적인 사용에 따른 온실가스의 방출은 지구온난화를 촉진시켰다. 개발된 회분식 공정을 적용하는 음식물쓰레기 수소발효에서, 세계 최초로 수소 전환율과 초기 및 운전 pH와의 관계를 수학적으로 표현하였고, 동시에 최적화하였다. 최적 초기 및 운전 pH는 각각 7.50, 6.01이었다. 축산폐수를 음식물쓰레기의 수소발효에 보조기질로 첨가 시 pH 제어를 위해 요구되는 알칼리량을 감소시킴과 동시에 수소발생률도 크게 증대시킬 수 있음을 관찰할 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제10권2호
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• pp.131-138
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• 1989

In this paper the feature of background EEG is extracted by LS Prony Method for the analysis of background EEG in the time domain. Autocorrelation leg estimates are not required with the LS Prony method. The Prony method is required any the solution of two serfs of simultaneous linear equation and a polynominal rooting. That the optimal order of this model is the 6-th order is determined by using Akaike' s Information Criterial test. From the experimential results the alpha band amplitude is the largest among alpha band beta band theta band delta band and beta band amplitude is larger than that of the delta band and theta band. The sustained time for the alph a band, the beta band, the delta band and the theta band is 2, 3461 (sec), 0.6490(sec), 0.3120(sec), 0.7046(sec) respectively. Consequenty the alpha band is maintained in the whole subjects, the beta band, the delta band, the theta band are existed intermittently in each subjects.

• 약학회지
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• 제13권1호
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• pp.1-15
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• 1969

A new method of qualitative and quantitative determination of barbiturates in the pharmaceuticals by means of $\alpha$-picoline-copper (II) was studied. Barbiturates in the pharmaceuticals were dissolved in the mixed solvent of 33% $\alpha$-picoline-Carbontetrachloride to yield Complex Compounds of barbiturates-copper (II)-$\alpha$-picoline. Complex Compounds of barbiturates show uniformly maximum absorption at the wavelength of 540m.mu. and wre to be identified at the concentration of 1 X 10$^{-4}$ Mole, and also was to be quantitatively determined at the concentration of 1 X 10$^{-3}$ Mole. By this method barbiturates in the pharmaceuticals could be determined in the presence of various compounds such as sulpyrine, isopropylantipyrine, antipyrine, phenacetin and etc. But Barbiturates could be also determined by this method after seperation with aminopyrine, acetaminophen, acetylsalicylic acid and etc. by column chromatography. And barbiturates and acetylsalicylic acid could be also determined by simultaneous equation while their complex compounds show uniformly each maximum absorption at the Wavelength of 540 m${\mu}$ and 620 m${\mu}$. I.R. spectra of these complex compounds show identification of Barbiturates derivatives. The composition ratio of these complex compounds were : barbiturates : Cu : ${\alpha}$-picoline=2:1:2.

• 터널과지하공간
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• 제2권2호
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• pp.199-211
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• 1992

Blasting vibrations of 3 quarries and 5 construction sites were measured and investigated with two reference data. Square and cubic root scaled distance were similar in fitness to peak particle velocity of individual blasting site, but the former is better fitted in total. It was suggested that the limit scaled distance for domestic surface blasting be 40kg/$\textrm{cm}^2$ for 10mm/s level and 60kg/$\textrm{cm}^2$ for 5mm/s level, which were lower than the OSM's regulation. Prevailing vibration components were in the order of radial, vertical and transverse directions. Prevailing vibration components were in the order of radial, vertical and transverse directons. Site factors K and m were 242 and -1.283 for all studied area, 357 and -1.348 for construction sites, 118 and -1.160 for quarries. Most prevailing frequency was in the range of 10~2Hz. Overlapping effect of delayed blasting vibrations were insignificant. Vibration history of delayed blasting was longer than simultaneous blasting, and it became longer as measuring distance increased. Wave form and predominant frequencies were more complicated for delayed blasting than instantaneous blasting. The influence of blasting scale and measuring distance were not significant to determine peak particle velocity equation.

• 대한기계학회논문집A
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• 제26권12호
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• pp.2647-2655
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• 2002

This research presents an analytical model to investigate the stability due to the ball bearing waviness i n a rotating system supported by two ball bearings. The stiffness of a ball bearing changes periodically due to the waviness in the rolling elements as the rotor rotates, and it can be calculated by differentiating the nonlinear contact forces. The linearized equations of motion can be represented as a parametrically excited system in the form of Mathieu's equation, because the stiffness coefficients have time -varying components due to the waviness. Their solution can be assumed as a Fourier series expansion so that the equations of motion can be rewritten as the simultaneous algebraic equations with respect to the Fourier coefficients. Then, stability can be determined by solving the Hill's infinite determinant of these algebraic equations. The validity of this research is proved by comparing the stability chart with the time responses of the vibration model suggested by prior researches. This research shows that the waviness in the rolling elements of a ball bearing generates the time-varying component of the stiffness coefficient, whose frequency is called the frequency of the parametric excitation. It also shows that the instability takes place from the positions in which the ratio of the natural frequency to the frequency of the parametric excitation corresponds to i/2 (i=1,2,3..).

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.437-442
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• 2001

계통연계형 태양광 발전 시스템은 태양 에너지를 전기 에너지로 변환하는 태양 전지부와 발생 전력을 계통에 연계하는 진력변환장치로 크게 나눌 수 있다. 또한 전력변환부는 승압용 컨버터부와 DC전력을 AC로 변환하는 인버터부로 구성된다. 종래 인버터의 주회로 방식은 저주파 트랜스나 고주파 트랜스를 사용하는 방식이 채러되었으나, 최근 이러한 방식에 비해 소형 경량화가 기대되는 트랜스리스 방식이 많이 연구되고 있다. 본 논문의 승압부는 2상 부스트 컨버터를 이용하여 입력 전류와 출력 전압의 리플을 줄여, 각 전력 소자의 전압 스트레스를 줄이고, 입력 리액터를 소형화한다. 그리고, 인버터 부의 출력 고조파 성분을 저감하기 위해 정현파 PWM에서 얻어진 스위칭 시간을 기본값으로 하여 푸리에 급수로 유도한 PWM 스위칭 시간을 채택하였고, PSpice를 이용하여 변환기의 동작을 시뮬레이션하여 그 유효성을 검증하였다.