• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.1
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• pp.6-10
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• 2010

A measurement of very high torque for track drive unit in construction equipment is usually in difficulties due to the requirement of a torque meter with high capacity, and the limitation of geometry for an experimental set-up. To improve the troublesome problem, a new device was proposed, where a torque transmitted through the torque arm can be measured by load cells attached at each torque arm. The experimental set-up of the new device was carried out in order to measure the torque values for a mechanical feedback type planetary gear box, in which the power flow circulates itself in a closed-loop. The new device enables to measure torque values of 60,000Nm. Additionally, the measured values were estimated statistically in the aspect of their repeatability and reproducibility, so that an acceptable behaviour as a measuring device can be confirmed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.10
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• pp.649-656
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• 2010

The aim of this study is to investigate the influence of the secondary fluid flow rate through GLHX on a GSHP system with vertical single U-tube type GLHXs. The COP of a GSHP system with large flow rate was lower than it with small flow rate due to large power consumption of ground loop circulating pump. It is suggested that the heat pump unit with high COP and low flow rate through the GLHX have to be selected in order to enhance the performance of the system and reduce the length of GLHX.

• KIPE Magazine
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• v.13 no.4
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• pp.28-32
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• 2008

Power Supply Designer는 부품설계, large-sign -al 시뮬레이션, feedback control design 그리고 소신호 해석 등 완전한 스위칭 전원공급장치(SMPS)의 설계를 위한 시뮬레이션 프로그램입니다. 또한 최종 정확도 모델링 기술을 사용한 전류-모드 시뮬레이션, CCM & DCM 컨버터 시뮬레이션, loop gain이 포함된 컨트롤 시스템의 해석, 필터 디자인 및 해석, 모든 주요 부품에 대한 파워손실 측정 및 스트레스 해석을 하기 위한 빠르고 순환적인 시뮬레이션과 시뮬레이션시 자주 발생하는 Convergence 에러를 최소화할 수 있는 Convergence 마법사 기능을 수행할 수 있습니다. Power Supply Designer는 ICAP/4 Power Delu -xe라는 시뮬레이터와 인덕터 및 트랜스포머를 설계할 수 있는 Magenetics Designer가 패키지로 구성이 되어 있는 제품입니다. Solar Pro는 일사량, 온도, 각 지역의 위치정보에 대한 데이터와 태양광모듈에 대한 데이터를 고려하여 그림자 분석, I-V계산, 발전량계산, 경제성분석을 제공하는 솔루션입니다. 또한 그림자의 궤적과 발전량을 계산하여 애니메이션으로 볼 수가 있고 경제성을 포함한 시스템 성능을 표시할 수 있기 때문에 태양광 설치 고객에게 태양광 발전 시스템 자체에 대한 이해와 설득력 있는 프리젠테이션을 할 수가 있습니다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.231-234
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• 2001

본 논문은 다단계 상호연결망에서 높은 처리율과 결함 허용을 위해 중복 경로를 제공하는 E-Cube-network 구조를 제안한다. Cube network의 확장된 형태인 E(Extended)-Cube network 구조를 통해 패킷 전송중 충돌이 발생한 경우 스위치 자신을 순환하고, 재차 충돌이 발생하면 멀티플렉서를 통해 또 다른 새로운 경로로 패킷을 전송하는 새로운 알고리즘을 제시한다. 그리고 모의실험을 통해 기존의 Cube network 구조보다 높은 종단간 처리율을 보인다.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.1
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• pp.46-58
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• 2024

Pollinators are organisms that carry out the pollination process of plants and include Hymenoptera, Lepidoptera, Diptera, and Coleoptera. Among them, bees not only pollinate plants but also improve urban green spaces damaged by land use changes, providing a habitat and food for birds and insects. Today, however, the number of pollinating plants is decreasing due to issues such as early flowering due to climate change, fragmentation of green spaces due to urbanization, and pesticide use, which in turn leads to a decline in bee populations. The decline of bee populations directly translates into problems, such as reduced biodiversity in cities and decreased food production. Urban beekeeping has been proposed as a strategy to address the decline of bee populations. However, there is a problem asurban beekeeping strategies are proposed without considering the complex structure of the socio-ecological system consisting of bees foraging and pollination activities and are therefore unsustainable. Therefore, this study aims to analyze the socio-ecological system of honeybees, which are pollinators, structurally using system thinking and propose a green space planning strategy to revitalize urban beekeeping. For this study, previous studies that centered on the social and ecological system of bees in cities were collected and reviewed to establish the system area and derive the main variables for creating a causal loop diagram. Second, the ecological structure of bees' foraging and pollination activities and the structure of bees' ecological system in the city were analyzed, as was the social-ecological system structure of urban beekeeping by creating an individual causal loop diagram. Finally, the socio-ecological system structure of honey bees was analyzed from a holistic perspective through the creation of an integrated causal loop diagram. Citizen participation programs, local government investment, and the creation of urban parks and green spaces in idle spaces were suggestedas green space planning strategies to revitalize urban beekeeping. The results of this study differ from previous studies in that the ecological structure of bees and the social structure of urban beekeeping were analyzed from a holistic perspective using systems thinking to propose strategies, policy recommendations, and implications for introducing sustainable urban beekeeping.

• Korean Journal of Construction Engineering and Management
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• v.6 no.3 s.25
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• pp.144-155
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• 2005

Since 1950s, the Korean housing market has continually experienced the chronicle lack of housing stock because of lower housing investment in comparison with a population explosion, prompt urbanization and rapid restructuring of family. The Korean housing market have thus been driven not by the pricing model by housing demand-supply chain but by the Korean housing policies focusing on the increase of housing supply and the living stability of the middle or low-income bracket. After all, repetitive economic vicious circle of housing price and the increase of unsold apartments aggravated the malfunction of the Korean housing market. Meanwhile, the Korean construction firms have exacerbated their profitability. Such terrible situations are mainly triggered by the Korean construction firms that weighed on the short-term profits and quick response of the government policy alterations rather than the prospect of housing market Therefore, this research focusing on the dynamics of housing market identified and classified the demand and supply elements that consist not only of housing system structures but also of the environmental elements that affect the structures. Based on the system thinking and traditional theory of consumer's choice, the interactions of these elements were constructed as a causal loop diagram that explains the mutual influences among housing subsystems with feedback loops. This paper describes and discusses about the causes of the dynamic changes in the Korean housing market. This study would help housing suppliers, including housing developers, construction firms, etc., to form a more comprehensive understanding on the fundamental issues that constitute the Korean housing market and thereby increasing their long term as well as minimizing the risk involved in the housing supply businesses.

• Journal of Broadcast Engineering
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• v.25 no.2
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• pp.157-165
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• 2020

In this paper. we propose an effective compensation scheme to the quantization error arisen from quantized learning in a machine learning on an embedded system. In the machine learning based on a gradient descent or nonlinear signal processing, the quantization error generates early vanishing of a gradient and occurs the degradation of learning performance. To compensate such quantization error, we derive an orthogonal compensation vector with respect to a maximum component of the gradient vector. Moreover, instead of the conventional constant learning rate, we propose the adaptive learning rate algorithm without any inner loop to select the step size, based on a nonlinear optimization technique. The simulation results show that the optimization solver based on the proposed quantized method represents sufficient learning performance.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.236-246
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• 2003

This paper is implemented a control algorithm in order to be stable and minimized to entire train traffic system at delayed case. Signal ing system is described wi th algebraic equations given for train headway, Discrete-event simulation principles are reviewed and a demonstration block signaling model using the technique is implemented. Train congestion at station entrance for short headway operation is demonstrated and the propagation of delays along a platform of trains from any imposed delay to the leading train is also shown. A rail way signaling system is by nature a distributed operation with event triggered at discrete intervals. Although the train kinematic variables of position, velocity, and acceleration are continually changing, the changes are triggered when the trains pass over section boundaries and arrive at signals and route switches. This paper deals with linear-mode1ing, stability and optimal control for the traffic on such metro line of the model is reconstructed in order to adapt the circuits. This paper propose optimal control laws wi th state feedback ensuring the stability of the modeled system for circuits. Simulation results show the benefit to be expected from an efficient traffic control. The main results are summarized as follows: 1. In this paper we develop a linear model describing the traffic for both loop lines, two state space equations have been analyzed. The first one is adapted to the situation where a complete nominal time schedule is available while second one is adapted when only the nominal time interval between trains is known, in both cases we show the unstability of the traffic when the proceeding train is delayed following properties, - They are easily implemented at law cost on existing lines. - They ensure the exponetial stability of loop system. 2. These control laws have been tested on a traffic simulation software taking into the non-linearites and the physical constraints on a metro line. By means of simulation, the efficiency of the proposed optimal control laws are shown.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.360-365
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• 2005

SMB (simulated moving bed) is a continuous chromatographic process by shifting periodically port position. Binary of mixture, Blue dextran and Orange G, was separated by SMB. These components have unique color individually, that is, Blue dextran is blue and Orange G is orange. It is easy to understand SMB process by observing the shift of color changes in SMB. These components was not adsorbed to stationary phase and isolated by difference of size exclusion factor. Mass transfer coefficient was determined by single pulse test under several flow rate conditions. Operation condition was obtained by standing wave theory and optimized for high purities in extract and raffinate streams. Experiment was performed in open loop 4 zone (2-2-2-2) SMB. There are several advantages in open loop SMB, where extract is product for high purity. It is also easy to control flow rate and monitor experimental state during operation. Experimental, extract and raffinate history is well fitted with simulation results, however, column concentration profile is a little different from simulation results. Purities were 99.5％ for extract and 98.9％ for raffinate and extract and raffinate yields were obtained as 98.9％ and 99.4％ respectively.

• Design Convergence Study
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• v.15 no.5
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• pp.55-70
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• 2016

Multi shopping malls provide us new life-style nowadays with the term, malling. Multi shopping malls are consisted of selling space, entertainment space and convenience space so that arrangement and circulation planning of each facilities have large influence to users. Based on this influences, this study aims to provide basic data for multi shopping malls' circulation planning. Therefore, this study selected 6 multi shopping malls in Seoul and conducted survey that satisfaction of circulation planning of multi shopping malls. For user satisfaction investigation, we studied concept of multi shopping mall following Korean building act and selected composition and characteristics of circulation. Also, we classified the malls to size and circulation shapes for comparison of the satisfaction results. Classified types are high-rise and low-rise and they are separated to small size and big size. In addition, classified circulation shapes are categorized to net type, loop type, cyclical loop type and multi type by forms of central space and main stream of the malls.