• 한국정밀공학회지
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• 제33권6호
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• pp.517-523
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• 2016

Unlike household refrigerators, commercial refrigerators are composed of separate indoor and outdoor units. The outdoor unit of most commercial refrigerators is designed to run at a fixed speed, which results in low energy efficiency and loud fan noise. Moreover, it cannot respond flexibly to changing thermal load in the indoor unit. Inverter type outdoor units can address such problems through speed changes based on information obtained from the indoor unit. However, using two units from different manufacturers is often not a viable solution. If condition changes in the indoor unit can be detected without communication between the two units, it is possible to adjust the speed of the outdoor unit. This paper attempts to analyze the signal from the outdoor unit when the condition of the indoor unit changes by varying the thermal load.

• 콘크리트학회논문집
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• 제12권5호
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• pp.25-34
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• 2000

When concrete is placed underwater, it is diluted with separating cementitious material and as a result the quality of concrete becomes poor. To solve this problem, antiwashout underwater concrete is increasingly used for the construction and repair of the concrete structure underwater. The objective of this study is to investigate the characteristics of antiwashout underwater concrete as to the mix proportion, casting and curing water through experimental researches. The unit weight of water and cement, water-cement ratio, fine aggregate ratio, unit weight of antiwashout underwater agent and superplasticizer, and casting and curing water were chosen to measure the suspended solids, pH, air contents, slump flow, unit weight of hardened concrete, and compressive strength. From this study, the incremental modulus at mix proportion design and unit weight of antiwashout underwater agent were increased more than fresh water, and it is a optimum mix proportion that the unit weight of water(and cement) is 230kg/$\textrm{m}^3$(460kg/$\textrm{m}^3$), waterOcement ratio is 50%, fine aggregate ratio is 40%, unit weight of antiwashout underwater agent is 1.2% of water contents per unit weight of concrete, and unit weight of supeplasticizer is 2.5% of cement contents per unit weight of concrete when the antiwashout underwater concrete is used for the underwater work of ocean.

• 한국주거학회논문집
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• 제11권2호
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• pp.129-137
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• 2000

This study is about the difference of South and East facing Cooling load of Apartment s Houses using Dynamic Heat-flow Calculation. Therefore, the purpose of this study is come in to use Material for the Thermal Environments of Apartment Houses. The results of the analysis are below. (1) For the peak load of degree hour; The highest is "I" unit and the next high load is H, F, E, C, B, G, D and A unit for the south facing Apartment houses. The higher load is "H" unit and the next high load is I, E, F, B, C, G, D, A Unit for the east facing Apartment houses. (2) For the total load of degree day; The highest load is "I" unit and the next high load is H, G, F, E, C, B, D and A Unit for the south facing Apartment houses. The highest load is "H" unit and the next high load is I, G, E, F, B, C, D, A Unit for the east facing Apartment houses. (3) For the total load of degree day; The highest load is "H" Unit for the east facing Apartment houses and the Lowest load is "A" Unit for the south facing Apartment houses.is "A" Unit for the south facing Apartment houses.nt houses.

• Journal of Biosystems Engineering
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• 제25권5호
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• pp.341-350
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• 2000

This study was conducted to develop a control unit for a tying device of a variable chamber round baler. The work process of the tying device was thoroughly analyzed and the control sequence was established according to the work process. Based on this control sequence, a control unit using an 8 bit microprocessor AT 89C52 as a CPU was developed. The driving circuit to control the actuator motion was developed and the PWM method was used to regulate the velocity of the actuator. On the front panel of the control unit, indicators were also installed to show the operations being conducted. A prototype of the developed control unit was manufactured and tested. A total of 50 complete cycles of the control sequence was repeated and no failure was observed. It was evaluated that the developed control unit has an excellent performance and can be used practically for variable chamber round balers.

• 한국수자원학회논문집
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• 제44권1호
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• pp.41-49
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• 2011

본 연구는 한 유역 내에서 단위유량도의 첨두치가 강우 강도에 따라 변동되는 기존 연구 분석 사례를 근간으로 하여 고찰된다. 시간불변이라는 이론적 기본 가정과 달리 호우별 강우강도에 따라 시변(時變)하는 단위유량도를 설정하고 강우사상에 적용하여 유출수문곡선을 산출하여 검토한다. 이 때 적용되는 단위유량도의 경우 첨두유량과 첨두발생시간은 기왕 연구된 강우강도와의 관계식을 검토하여 이용하고 단위유량도 형상은 산출된 첨두치를 적용한 Nash의 단위유량도로 설정된다. 비교 목적을 위해서 적용하는 유역 평균 단위유량도는 강우사상별로 유도된 26개의 단위유량도의 평균 첨두치에 의한 Nash의 모형이다. 호우사상의 강우강도별로 변동되는 단위유량도와 평균단위유량도로부터 산출된 수문곡선의 첨두유량과 첨두발생시간을 관측수문곡선과 비교한다. 비교한 결과 본 연구에서 보완적으로 제시한 시변(時變)의 단위유량도는 평균 단위유량도에 의해서 계산한 첨두홍수량과 첨두발생시간 보다 관측치에 접근함을 보인다.

• 대한수학회지
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• 제54권1호
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• pp.177-191
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• 2017

In this note we consider the right unit-duo ring property on the powers of elements, and introduce the concept of weakly right unit-duo ring. We investigate first the properties of weakly right unit-duo rings which are useful to the study of related studies. We observe next various kinds of relations and examples of weakly right unit-duo rings which do roles in ring theory.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권11호
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• pp.521-527
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• 2002

The Hemodialysis system is the device for the patients who have suffered from end stage renal failure as the kidney which removes the waste products in a human body. The existing hemodialysis is based on a 8-bit micro-controller and it is not a touch-screen type but a manual type. This paper is focused on hemodialysis system based on high control and expension embedded system. The whole system consists of main control unit and sub control unit(dialysis control unit, blood control unit, monitoring control unit, networking unit). The dialysis control unit, blood control unit, monitoring control unit are processed by 3 microcontrollers and network unit is for monitoring a renal failure patient's condition. For the evaluation of the system performance, the saline was pured into blood unit and then water removal rate, conductivity and temperature of hemodialysis liquid were measured 10 times in an each state suing the UF pump in the fluid unit varing the quantity of saline to 1000cc, 2000cc, 3000cc and 4000cc. As a result, the rates of water removal are 98.6% in condition of 000cc saline, 96.9% in 2000cc, 98.9% in 3000cc and 98.3% in 4000cc. The conductivities of hemodialysis liquid are 99.6% in the first to third condition and 99.7% in the forth condition. The temperatures of hemodialysis liquid are 99.8% in the first to third condition and 99.6% in th forth condition.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.894-900
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• 2005

A new approach to the straightforward implementation of the unscented filter in a unit quaternion space is proposed for spacecraft attitude estimation. Since the unscented filter is formulated in a vector space and the unit quaternions do not belong to a vector space but lie on a nonlinear manifold, the weighted sum of quaternion samples does not produce a unit quaternion estimate. To overcome this difficulty, a method of weighted mean computation for quaternions is derived in rotational space, leading to a quaternion with unit norm. A quaternion multiplication is used for predicted covariance computation and quaternion update, which makes a quaternion in a filter lie in the unit quaternion space. Since the quaternion process noise increases the uncertainty in attitude orientation, modeling it either as the vector part of a quaternion or as a rotation vector is considered. Simulation results illustrate that the proposed approach successfully estimates spacecraft attitude for large initial errors and high tip-off rates, and modeling the quaternion process noise as a rotation vector is more optimal than handling it as the vector part of a quaternion.

• International Journal of Human Ecology
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• 제5권2호
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• pp.81-91
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• 2004

The purpose of this study is to evaluate consumer use of unit price information introduced in Korea 1999. A total of 571 observations were analyzed by frequency, percent, and paired t-test using SPSS. The main findings are (1) consumers use unit price information to make better purchase decisions, (2) consumers with higher than average attentiveness in purchase behavior utilize unit price information to make better buying decisions, and (3) consumers with higher than average knowledge utilize unit price information to make better buying decisions. (4) Also if either attentiveness in purchase behavior or consumer knowledge is lower than average, unit price information helped consumers make better purchase decisions. (5) However, there was no difference among those consumers with below average or above average attentiveness and knowledge.

• 대한수학회논문집
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• 제13권4호
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• pp.913-931
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• 1998

Using invariant theory, new invariant cubature formulas over a unit cube are given by imposing a group structure on the formulas. Cools and Haegemans [Computing 40, 139-146 (1988)] constructed invariant cubature formulas over a unit square. Since there exists a problem in directly extending their ideas over the unit square which were obtained by using a concept of good integrity basis to some constructions of invariant cubature formulas over the unit cube, a Reynold operator will be used to obtain new invariant cubature formulas over the unit cube. In order to practically find integration nodes and weights for the cubature formulas, it is required to solve a system of nonlinear equations. With an IMSL subroutine DUNLSF which is used for solutions of the system of nonlinear equations, we shall give integration nodes for the new invariant cubature formulas over the unit cube depending on each degree of polynomial precision.