• 대한전자공학회논문지
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• 제14권1호
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• pp.23-28
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• 1977

본논문은 고주파유도가열전원으로 주목을 끌고있는 SCR inverter의 실용적인 설계에 관한 것이다. 시간적으로 변화하는 부하에 대하여, 주파수제어방식에 의하여 출력과 역률을 일정하게 유지하도록 설계하여, 그특성을 측정검토한바, 만족스러운 결과를 얻었다. 시작시험한 inverter dir 3[KHz], 3[KW]의 것이었다.

• Journal of Information Display
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• 제10권1호
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• pp.19-23
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• 2009

In this paper, we review the proposed liquid crystal display (LCD) with a tunable viewing angle consisting of a conventional liquid crystal display (LCD) panel and a thermally variable retardation layer (TVRL) characterized by uniformly aligned LC film with transparent indium-tin-oxide electrodes for Joule heating. In the TVRL, nematic phase is transitioned into isotropic by Joule heating. The numerical calculation showed that the intrinsic wide viewing angle was achieved at the isotropic phase of the TVRL by Joule heating, whereas the narrow viewing angle was obtained at the nematic phase of the TVRL. The simulated and experimental results of the proposed LCD show continuous and symmetrical viewing angle characteristics by tuning the retardation of TVRL using Joule heating. The structure of the viewing angle control proposed here is adoptable to all LCD modes with wide viewing angle characteristics.

• 설비공학논문집
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• 제6권2호
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• pp.78-92
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• 1994

Thermal performance of pipe network of continuous heating system controlled by thermostat and flow control valve was simulated in consideration of radiation heat transfer and solved by linear analysis method. Thermal performance of real apartment building with radiant floor heating system was simulated by equivalence heat resistance-capacity method. This method enables to simulate the unsteady variation of temperature or each element of building. Heat transfer characteristics of each element were also investigated.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.323-324
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• 2006

The nanostructure control of $Si_3N_4$ ceramics can be achieved by using fine starting powder and retardation of grain growth. The spark plasma sintering technique is useful to retard the grain growth by rapid heating. In the present work, the change of microstructure was investigated with emphasis on the particle size of starting powder, the amount of sintering additive and the heating schedule. The rapid heating by spark plasma sintering gave the fine microstructure consisting of equiaxed grains with the same size as starting particles. The spark plasma sintering of $Si_3N_4$ fine powder was effective to control the microstrucutre on nano-meter level.

• 대한기계학회논문집B
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• 제21권5호
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• pp.670-678
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• 1997

A method to mitigate the thermal stratification phenomenon of pressurizer surge line is proposed by heating bottom outside of horizontal pipe. Unsteady two dimensional model has been used to numerically investigate an effect of heating the bottom of pipe. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature and streamline profiles of fluids and pipe walls with time are compared with the previous study result. The numerical result of this study shows that the outside heating can relaxate the thermal stratification flow of the pressurizer surge line. Maximum dimensionless temperature difference between hot and cold sections of the pipe inner wall which causes thermal stratification was reduced from 0.514 to 0.424 at dimensionless time 1, 632 and 1, 500 respectively.

• 대한핵의학회지
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• 제33권4호
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• pp.430-438
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• 1999

목적: 마이크로웨이브를 이용한 방사성 동위원소의 표지와 Sep-Pak 카트리지를 이용한 정도관리 방법의 개선으로 신속한 제조가 가능하면서도 높은 표지효율을 가진 방사성 의약품을 얻고자 하였다. 대상 및 방법: $C_{18}$ 그리고 alumina N Sep-Pak카트리지를 이용한 정도관리 방법을 $^{99m}Tc$-ECD, $^{99m}Tc$-MIBI, $^{99m}Tc-MAG_3$에 적용하였고 표지효율을 측정하였다. 마이크로웨이브를 사용하여 상기의 키트에 방사성 동위원소를 표지하여 표지효율을 비교하였다. 결과: 마이크로웨이브에 의해 생성된 세 가지방사성 의약품은 3 ml용액에 $^{99m}Tc$-ECD와 $^{99m}Tc$-MIBI는 10초, $^{99m}Tc-MAG_3$는 15초의 짧은 마이크로웨이브를 조사하여 모두 95% 이상의 표지효율을 나타내었다. $^{99m}Tc$-ECD와 $^{99m}Tc$-MIBI는 Sep-Pak alumina N 카트리지를 사용하여 짧은 시간 내에서도 정확한 정도관리 결과를 얻을 수 있었다. 방사성 의약품의 제조시간은 정도관리를 포함하여 모두 6분 이하를 나타내었다. 결론: Sep-Pak 카트리지를 이용한 정도관리 방법과 마이크로웨이브에 의한 방사성 의약품의 제조 방법은 일상적인 방사성 의약품의 제조에 적용이 가능하였으며, 방사성 의약품의 제조시간을 크게 단축시킬 수 있었다.

• 아시안잔디학회지
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• 제23권2호
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• pp.279-286
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• 2009

빌딩에서 발생하는 폐열을 활용할 목적으로 동절기 옥상정원에서 푸른 잔디를 유지하기 위한 잔디생육시험을 실시하였다. 옥상정원 지반에 Heating system을 설치하여 시기별 잔디생육상태를 조사한 결과는 다음과 같다. 겨울철 옥상녹화 지반을 heating처리한 결과, 무처리구에 비해 잔디품질 및 피복률이 우수하였으며, 잔디의 뿌리길이, 잔디밀도가 모두 상승하였다. 표면온도를 비교한 결과, heating지반의 온도는 평균 $10.9^{\circ}C$로 $0^{\circ}C$를 유지하였던 무처리 지반에 비해 월등히 높았으나, 수분함량은 평균 1.9% 낮아진 것은 $10.9^{\circ}C$로 유지된 지온으로 인해 수분증발이 계속 이루지는 것으로 사료되었다. 적설량이 15cm 이상 쌓인 상황에서, 히팅 시스템이 설치된 잔디밭에서는 4일만 눈이 완전히 녹았으나 대조구에서는 적설량의 변화가 거의 없었다. Heating system의 보일러 수온을 $55^{\circ}C$에서 $60^{\circ}C$로 높이자, 잔디는 건조 스트레스를 받아 잎끝이 마르는 증상이 나타났다. 앞으로 옥상정원에서의 잔디 재배과 관계된 세부적인 생리적 스트레스에 관한 연구가 필요하다고 판단된다.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1042-1050
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• 2003

A heating flow discharged from a 4-way ceiling type indoor unit has been investigated to determine the design parameters for the optimal flow control. The flow was measured by a PIV(particle image velocimetry) system and an experimental model of 1/10 scale with a transparent room was devised by satisfying the Archimedes number. This similarity is generally used in cases where the forced convection has similar magnitude of the natural convection. To optimize the heating flow, several vane angles and vane control algorithms of cross and right angle controls were considered. Regarding the vane angle, experimental results show that 30$^{\circ}$is an optimal angle to avoid re-suction flows without significant increase in flow noise. Temperature distribution measured in the environmental chamber ensures the increased thermal comfort when compared to the case, 60$^{\circ}$angle. At the optimal angle, applying open/close control gives rise to more uniform distribution of the heating flow than without control. Especially, the cross-control seems to be satisfactory for thermal comfort.

• 시스템엔지니어링학술지
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• 제12권1호
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• pp.113-120
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• 2016

Steel in a continuous reheat furnace is heated to higher temperature to be treated in the rolling steel process. Due to this reason the continuous reheat furnace system requires an optimal control system to adjust the temperature inside the furnace. Level 2 control systems for continuous reheat furnaces generate automatic heating set points for the level 1 system of the furnace based on the mathematical thermal model which can give a good estimation of steel heating inside the furnace and is used to adjust heating requirements to optimize furnace combustion. For the current study the analytic methodology based on the design procedure from the systems engineering to develop new level 2 control system of a continuous reheat furnace was proposed. The system analysis and the requirements of the level 2 control system were derived using the unified modeling language (UML) 2.0, and the design of database and the graphic user interface (GUI) for the level 2 control system were conducted.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1383-1388
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• 2015

Proportional integral derivative (PID) control is one of the conventional control strategies. Industrial PID control has many options, tools, and parameters for dealing with the wide spectrum of difficulties and opportunities in manufacturing plants. It has a simple control structure that is easy to understand and relatively easy to tune. Injection mold is warming up to the idea of cycling the tool surface temperature during the molding cycle rather than keeping it constant. This “heating and cooling” process has rapidly gained popularity abroad. However, it has discovered that raising the mold wall temperature above the resin’s glass-transition or crystalline melting temperature during the filling stage is followed by rapid cooling and improved product performance in applications from automotive to packaging to optics. In previous studies, optimization methods were mainly selected on the basis of the subjective experience. Appropriate techniques are necessary to optimize the cooling channels for the injection mold. In this study, a digital signal processor (DSP)-based PID control system is applied to injection molding machines. The main aim of this study is to optimize the control of the proposed structure, including a digital PID control method with a DSP chip in the injection molding machine.