• 가족자원경영과 정책
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• 제9권4호
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• pp.21-40
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• 2005

The purpose of this study was to exam the activities by the distribution of time and space occupancy on their weekday and weekend. to study the space and labor segregation by sex. The sample population included 23 wives and their husbands(30-40 years old). The major findings of the research are as follows: First, it shows that wives' time use by activity was consistent with the space occupancy on weekday. Second, on weekend, wives was used to stay in living room most of time. Thirdly, husbands show the stereotype of time use on weekday, and substitute leisure time for labor time. Finally, on weekend, the wives and husbands have the joint time in the household labor or leisure activities.

• 대한수학회논문집
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• 제33권1호
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• pp.305-315
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• 2018

This note provides a study of lightlike hypersurfaces of a generalized Robertson-Walker(GRW) space-time with a certain screen distribution, which are integrable and have good properties. Focus is to investigate geometric features from the relation of the second fundamental forms between lightlike hypersurfaces and leaves of the integrable screen distribution. Also, we shall apply those results on lightlike hypersurfaces of a GRW space-time to lightlike hypersurfaces of a Robertson-Walker(RW) space-time.

• 방사선산업학회지
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• 제4권1호
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• pp.85-89
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• 2010

The radioactive experiments are carried out for diagnosis of a variety of industrial processes in terms of the operation condition and the efficiency by measuring the residence time distribution. However, it is not easy to interpret the residence time distribution using the conventional methods when the flow rate is not constant and a number of processes are coupled in a complicated manner. In these cases, they can be analyzed by describing the system with mathematical models that can be defined with the state-space equations. In this paper, the residence time distribution of sludge was measured with a radiotracer, $^{46}Sc-EDTA$, in the digester of which the flow rate varies with time. The digester was assumed as a linear time variant system since the flow rate changed during the experiment and the operation efficiency of the digester was calculated by applying the state-spae equations.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권9호
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• pp.502-509
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• 2000

In this paper in order to evaluat quantitavely the formation mechanism of space charge and its effects on the conduction characteristics in LDPE we have carried out the numerical analysis on the basis of experimental results of space charge distribution cathode field and current with time which had been simultaneously measured at applied field of 50kV/mm and room temperature. As the models for numerical analysis we employ the Richarson-Schottky theory for charge injection from electrode into LDPE and the band-tail conduction at crystalline regions and the hopping conduction by traps which mainly exist at the interface regions of crystalline-amorphous region for charge transport in LDPE. Futhermore in order to investigate the influence of physical parameters on the time characteristcs of space charge distribution and measured current we have changed the values of trap density activation energies for charge injection and transport and have analyzed their effects.

• 한국경제지리학회지
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• 제18권1호
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• pp.87-102
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• 2015

본 연구에서는 정보통신정책연구원에서 실시하고 있는 미디어패널조사에서 얻어진 미디어 이용자들의 미디어 다이어리 데이터에서 미디어 수용자들의 활동공간 이용 시공간 정보를 추출하고, 이를 활용하여 도시 실시간 인구분포를 산정하는 방법론을 제시하고자 한다. 이를 위하여 도시민의 시공간 정보가 상대적으로 다양하여 비교검토가 가능한 서울시를 연구대상 지역으로 선정하고, 서울시 미디어 이용자들이 도시민들의 주요 활동공간인 주거, 업무, 교육, 교통, 상거래 등 다양한 활동공간별로 하루 중 시간 흐름에 따라 머무는 비율의 변화를 분석한다. 활동공간에 따라 하루 중 시간 흐름에 따라 머무는 인구비율은 상당한 차이를 보인다. 이러한 미디어 이용자의 시공간 정보 활용의 타당성을 확보하기 위하여 서울시 대중교통이용자의 시공간적 이동 정보를 담고 있는 교통카드 데이터에서 얻어진 내용과 비교한다. 도시민의 활동공간을 주거, 업무, 상거래의 활동공간으로 범주화하여 활동공간 범주별 실시간 인구 분포률을 산정하고, 이에 서울시 각 동별 거주 인구수 및 관련 산업별 고용자 수를 결합하여 서울시 동별 실시간 인구수를 산정한다. 서울에서 낮과 밤의 인구 분포에 나타나는 공간적 특성을 파악하기 위하여 주거 공간에 머무는 인구수에 가장 큰 격차를 보이는 오전 3시와 오후 3시 두 시점의 각 활동공간 범주별 및 이들을 총합한 실시간 인구수를 GIS를 활용 하여 지도화 하였다. 도시민의 대부분이 거주지를 떠나 일상과 관련된 활동공간에 머무르고 있는 오후 3시의 서울 실시간 인구분포는 업무공간과 상업공간의 분포가 결정적인 역할을 한다는 것을 확인할 수 있다. 반면에 밤 시간대의 인구분포는 주거공간 인구 분포와 거의 유사한 양상을 나타나고 있다.

• Journal of the Korean Statistical Society
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• 제28권1호
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• pp.93-106
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• 1999

In this paper we consider estimation of a real valued parameter in the drift coefficient of a Hilbert space valued Ito stochastic differential equation. First we consider observation of the corresponding diffusion in a fixed time interval [0, T] and prove the Bernstein - von Mises theorem concerning the convergence of posterior distribution of the parameter given the observation, suitably normalised and centered at the MLE, to the normal distribution as Tlongrightarrow$\infty$. As a consequence, the Bayes estimator of the drift parameter becomes asymptotically efficient and asymptotically equivalent to the MLE as Tlongrightarrow$\infty$. Next, we consider observation in a random time interval where the random time is determined by a predetermined level of precision. We show that the sequential MLE is better than the ordinary MLE in the sense that the former is unbiased, uniformly normally distributed and efficient but is latter is not so.

• 제어로봇시스템학회논문지
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• 제15권11호
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• pp.1144-1149
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• 2009

This paper deals with the time synchronization problem over SpaceWire links. SpaceWire is a standard for high-speed links and networks between spacecraft components, which was invented for better, cheaper, faster on-board data handling in spacecraft. The standard defines Time-Code for time distribution over SpaceWire network. When a Time-Code is transmitted, transmission delay and jitter is unavoidable. In this paper, a mechanism to remove Time-Code transmission delay and jitter over SpaceWire links is proposed and implemented with FPGA for validation. The proposed mechanism achieves high resolution clock synchronization over SpaceWire links, complies with the standard and can be easily adopted over SpaceWire network.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.302-309
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• 2017

The ageing of XLPE cable insulation will lead to the accelerating accumulation of space charge, which will greatly affect the safe operation of the HVDC cable. In order to investigate the influence of different ageing modes on the space charge distribution of the HVDC cable, thermal stressed, electrical stressed and electro-thermal stressed endurance tests were carried out on the XLPE peelings. The tested XLPE peelings were obtained from 160kV HVDC cable insulation. The endurance tests were carried at thermal stress of 363K, electrical stress of 20kV/mm DC and a combination of both. The Pulsed Electro-Acoustic (PEA) method was used to measure the space charge distribution of the samples. The influences of ageing on the trap energy distribution were analyzed based on the isothermal relaxation theory and the decay characteristics of the space charge. The results showed that thermal ageing would help to improve the crystalline morphologies of the XLPE at the early stage. The total amount of space charge decreased compared to the ones before thermal ageing. The long term of electrical stress would result in the cleavage of polymer molecule chains which would intensify the accumulation of space charge and increase the density and depth of electron traps. With a combination of electrical and thermal stress, the injection and migration of space charge were more significant. Besides, the depth and density of electron traps increased rapidly with the increase of endurance time.

• 한국실내디자인학회논문집
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• 제25권5호
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• pp.130-139
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• 2016

To determine "how humans move in space, what they want, and through which visual information they act and choose," this study aims to define in which sense space is preferred in gaze. The ultimate goal is to extract data of human visual awareness and preference in space. This study analyzed the observation characteristics perceived through observation frequency and time depending on the purpose cafe customers to understand what intension of visiting the space has on the observation characteristics which are the results obtained as information through visual perception. This research methods are as follows. First, the areas of preference in $caf{\acute{e}}$ space gazed by visual concentration are analyzed by divided into 12 by 12 grid A and B images separated depends on existence of people. Second, eye-tracking visual path in conscious gaze is analyzed to examine. Third, though the higher section frequency is likely to have more observation time, the interest area of I(3sec/180), II(6sec/360) and III(9sec/540) had higher frequency of Intention. The followings are the results of this study. First, the time range for searching or wandering and the observation characteristics could be estimated by the meaning of observation time by grade with the time-range out of the distribution of sections. Second, at the time distribution by section, when there was intention, the observation time was found to have higher occupation. In conclusion, this study is to determine the correlation of human concentration gazing at space images. It is an exploratory research on research methodologies, and aims to develop methodologies and provide basic data to plan attractive spaces in light of the subconscious of consumers in the future by interpreting gaze data related to concentration.

• Design & Manufacturing
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• 제12권2호
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• pp.5-10
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• 2018

Vacuum-assisted thermoforming is one of the critical steps for successful application of film insert molding(FIM) to parts of complex shape. In this study, the simulations and experiments of thermoforming processes were performed to investigate the effects of process conditions on thickness distribution and printed pattern deformation of films in vacuum-assisted thermoforming. The film thickness uniformity increased with decreasing film heating time, whereas it increased with increasing vacuum delay time. After thermoforming of films with uniform pattern space of 5mm, the maximum space was 9.432mm. Based on the simulation, a modified pattern was calculated to obtain uniform spaces after thermoforming. In the experiments for film with the modified pattern, the maximum space appeared 5.837mm. In, addition. the predicted patterns were in good agreement with the experimental results.