• 한국지진공학회논문집
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• 제25권5호
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• pp.223-232
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• 2021

The spatial variation characteristics of seismic motions at the nuclear power plant's site and structures were analyzed using earthquake records obtained at the Fukushima nuclear power plant during the Great East Japan Earthquake. The ground responses amplified as they approached the soil surface from the lower rock surface, and the amplification occurred intensively at about 50 m near the ground. Due to the soil layer's nonlinear characteristics caused by the strong seismic motion, the ground's natural frequency derived from the response spectrum ratio appeared to be smaller than that calculated from the shear wave velocity profile. The spatial variation of the peak ground acceleration at the ground surface of the power plant site showed a significant difference of about 0.6 g at the maximum. As a result of comparing the response spectrums at the basement of the structure with the design response spectrum, there was a large variability by each power plant unit. The difference was more significant in the Fukushima Daiichi site record, which showed larger peak ground acceleration at the surface. The earthquake motions input to the basement of the structure amplified according to the structure's height. The natural frequency obtained from the recorded results was lower than that indicated in the previous research. Also, the floor response spectrum change according to the location at the same height was investigated. The vertical response on the foundation surface showed a significant difference in spectral acceleration depending on the location. The amplified response in the structure showed a different variability depending on the type of structure and the target frequency.

• 한국지반환경공학회 논문집
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• 제11권4호
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• pp.19-24
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• 2010

사면의 거동에 관한 종래의 해석 기법은 사면거동을 시간과 변위의 2차원 크리프로 해석하는 것이었으나, 이러한 해석 기법은 강우에 의한 응력변화를 고려 않고 시간에 따른 변위만을 고려하여, 강우 시 사면의 거동 및 붕괴를 설명하지 못한다. 또한 강우에 의한 이력현상으로 인해 파괴면내의 전단에너지가 감소한다. 크리프 해석은 응력항을, 이력현상 해석은 시간항을 무시한 해석이므로, 두 가지 해석을 결합하여, 사면의 거동을 해석한다면, 응력변화, 변위 및 시간을 모두 고려한 실제 사면의 거동해석이 됨을 알 수 있다. 그러나 응력변화에 관한 항은, 강우로 인한 실제 사면의 침투 및 배수 시, 전단응력의 변화 및 전단강도의 변화를 동시에 유발하므로, 이 두 항을 동시에 고려할 수 있는 안전계수항으로 바꾸어야 한다. 본 논문은 강우의 지반침투 및 배수로 인하여 사면의 단위중량이 변하는 과정에 대한 크리프와 이력현상을 고려할 수 있는 결합해석으로 고찰하고 이에 따른 사면붕괴에 관한 전단응력과 전단강도의 변화 및 안전계수변화를 3차원으로 나타내고자 수행한 결과이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1257-1260
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• 1996

This paper describes a fully digitalized driver for BLDC motors and the driver is realized by a single chip microprocessor. The speed change can be done by using the signal obtained from the position detecting sensor and adjusting the pulse width at the input channel of power module. In order to verify the effectiveness, an repetitive control method is adopted in the speed control tracking a periodic reference change in the BLDC motor system. The experimental results are shown for the reference tracking accurately according to the design parameter variation in the repetitive controller design.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.483-484
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• 2008

In this paper, we present high-temperature characteristics of tunable all-optic filter using fiber Bragg grating(FBG), including peak reflectivity, FWHM bandwidth, refractive index change along temperature variation. The characteristics of a FBG tunable filter with refractive index change is affected by its thermal stability.

• 전력전자학회논문지
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• 제15권1호
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• pp.69-74
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• 2010

풍력발전기가 계통에 연계되어 운전 중 바람의 변동에 따라 유효전력이 변동하면 연계지점에서는 전압변동이 발생하며 풍력발전기의 연계 위치 (PCC, Point of Common Coupling) 에 따라 그 값은 변동한다. 본 논문에서는 이러한 계통 연계 지점의 전압변동이 이상 전원에서 PCC지점까지의 등가 선로 임피던스와 풍력발전기 출력 전류의 곱에 비례함을 보였으며 이러한 전압변동을 억제하기 위하여 필요한 무효전력 요구량을 해석적인 방법으로 구하였다. 만일 풍력발전기 출력단 인버터의 용량 제한에 의해 무효전력 주입량에 한계가 있거나 전압변동 허용범위가 주어진 경우에는 그에 따라 무효전력 주입량을 변화시킬 수 있다. 제안된 알고리즘을 가변속 풍력발전시스템의 출력단 인버터에 사용하면 수시로 변동하는 유효전력에 따라 무효전력 요구량을 실시간으로 계산함으로서 PCC전압변동을 최소화할 수 있다. 제안된 알고리즘의 타당성을 검증하기 위해 실제 서해 도서지역에 설치된 소형 풍력발전기 및 전력 시스템 파라메터를 사용하여 Matlab과 PSCAD/EMTDC 시뮬레이션을 수행하였다.

• 교육시설 논문지
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• 제21권2호
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• pp.13-24
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• 2014

This study compared and analyzed middle and high school's homebase and media space which are installed along with the introduction of subject classroom system operation method, with regard to the position of arrangement, the type of arrangement, and the change of area, etc. which were changed and applied per the phase of project. For this, design competitions were implemented since 2006 targeting the cases which participated in design directly-indirectly in the researcher's architectural firm, present construction documents among the selected BTL(Build-Transfer-Lease) were completed, and the examples of 10 schools(design competitions 2 schools, BTL selected plans 8 schools) were analyzed, which were operating variation type.

• 대한가정학회지
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• 제44권12호
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• pp.167-178
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• 2006

The purpose of this study is to analyze the transformed fashion design based on the principles of visual design. Wucius Wong classified the kinds of transformation techniques as internal variation, external variation, extension, superimposition, transfiguration, dislocation, and distortion, which create and modify the shape. And the kinds of shape grammar for transformation are rule deletion, rule addition, and rule transformation, which are applied to interpretate for the change of wearing, the specialization & development of clothes, and the avant-garde styles in subculture groups. The formative meanings of the transformed fashion design are multi-transformation with complexity, formal beauty pretending confusion, and the basis for new trend.

• Journal of Radiation Protection and Research
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• 제31권4호
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• pp.197-201
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• 2006

Daily and seasonal variations of the ambient gamma ray exposure rates were measured by using a pressurized ion chamber from January 2003 to December 2005 in the CheongJu Regional Radiation Monitoring Post and the patterns of the distributions were studied. The annual average of the daily variation of the exposure rate was $\sim0.17{\mu}R/h$. The exposure rate was found to be maximum during 8:00 am to 9:00 am and minimum during 8:00 pm to 10:00 pm. For the annual data, the exposure rate was the minimum during the month of February. The exposure rate increased from February to mid-October (except during the period from May to July with no change) and decreased from October to February. The seasonal variation was found to be about $1{\mu}R/h$. Most of the measured values (96%) of the exposure rates fell under the normal distribution with a deviation of less than 4.8% and the remaining 4% had large fluctuations caused mainly by the rainfalls.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.606-610
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• 2004

In this paper, we would like to explain about the structure analysis of wheel set as variation of contact position between wheel and rail. Measurement of interacted force between wheel and rail is necessary for running safety evaluation as important factor of derailment mechanism. It's necessary to running safety evaluation of rolling stock. Wheel unload and lateral force change as variation of contact position between wheel and rail. Interacted force between wheel and rail got as each contact position through computer simulation. This is necessary process as first research for evaluation of derailment phenomenon and running safety.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.598-605
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• 2000

The design of a current collection system of high speed train requires the fundamental understandings fer the dynamic characteristics of a catenary system and pantograph. The stiffness of the catenary system of high speed train has the varying characteristics for the change of the contact point with a pantograph, since the supporting pole and hanger make the different boundary conditions for the updown stiffness of a trolley wire. The variation of stiffness results in Mathiue equation, which characterizes the stability of the system. However, the two terms variation of the stiffness due to span length and hanger distance cannot be solved analytically. In this paper, the stiffness variations are calculated, and the physical reasoning of linear model and one term Mathieu equation are reviewed. And the numerical analysis for the two term variation of the stiffness is done for the several design parameters of the pantograph.