• Title/Summary/Keyword: Cooling and Heating

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Environmental Control of Plant Production Factory Using Programmable Logic Controller and Computer (PLC와 컴퓨터를 이용한 식물생산공장의 환경제어)

  • Kim Dong-Eok;Chang Yu-Seob;Kim Jong-Goo;Kim Hyeon-Hwan;Lee Dong-Hyeon;Chang Jin-Taek
    • Journal of Bio-Environment Control
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    • v.15 no.1
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    • pp.1-7
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    • 2006
  • This study was conducted to develop a system and an control algorithm for control the environment of a plant factory. The greenhouse control system for environmental control was largely composed of a computer and a PLC. The screen of control program was composed of a greenhouse figure which was included machinery and equipments for greenhouse, the graph of environmental factors of inside greenhouse and the image of greenhouse. In order to reduce temperature change, the operation time of ventilation window was changed by 3 stage according to difference between a target and present temperature. When is heating, a temperature variation was shown to be $16.7{\pm}0.8^{\circ}C$. When is cooling, a temperature variation was shown to be $23.1{\pm}0.6^{\circ}C$. When is humidifing, a humidity variation was shown to be $39.3{\pm}1.6^{\circ}C$ %RH. An environmental control system and a control algorithm were proved that it was shown a good performance in a control accuracy. So a computer control system should be adapted to a control system of a greenhouse and a plant factory.

An Experimental Study on the Performance Improvement of the Seasonal Energy Efficiency Ratio(SEER) of a Heat Pump by Optimizing Operating Parameters under Partial Load Conditions (부분부하 조건에서 히트펌프의 운전변수 최적화를 통한 냉방계절성능(SEER) 향상에 관한 실험적 연구)

  • Choi, Sungkyung;Lee, Sang Hun;Kim, Sunjae;Kim, Yongchan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.3
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    • pp.111-118
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    • 2017
  • Performance factors such as the EER(Energy Efficiency Ratio) and the COP (Coefficient of Performance) are being replaced by seasonal energy efficiency factors, like the SEER (Seasonal EER) and the SCOP (Seasonal COP) to evaluate the performance of a heat pump by the time of the year. Seasonal performance factors, such as the CSPF (Cooling Seasonal Performance Factor) and the HSPF (Heating Seasonal Performance Factor) are used to describe the heat pump's performance during the cool and hot seasons. In this study, the optimization of all heat pump's operating parameters was experimentally conducted to enhance the SEER based on the EU standard (EN 14825). Moreover, the SEER was improved by the compressor frequency, as well as indoor and outdoor fan speeds. In addition, the performance characteristics of the heat pump were studied under partial load conditions. As a result, the SEER was enhanced by 17% when the compressor frequency was optimized. An additional 2% improvement was achievable with the optimization of indoor and outdoor fan speeds.

Characterization of Thermo-optical Properties of Ferroelectric P(VDF-TrFE) Copolymer Using Febry-Perot Interferometer (Febry-Perot 간섭계를 이용한 강유전 P(VDF-TrFE) 폴리머 열광학 특성평가)

  • Song, Hyun-Cheol;Kim, Jin-Sang;Yoon, Seok-Jin;Jeong, Dae-Yong
    • Korean Journal of Materials Research
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    • v.19 no.4
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    • pp.228-231
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    • 2009
  • Phase transition in ferroelectric polymer is very interesting behavior and has been widely studied for real device applications, such as actuators and sensors. Through the phase transition, there is structural change resulting in the change of electrical and optical properties. In this study, we fabricated the Febry-Perot interferometer with the thin film of ferroelectric P(VDF-TrFE) 50/50 mol% copolymer, and thermo-optical properties were investigated. The effective thermo-optical coefficient of P(VDF-TrFE) was obtained as $2.3{\sim}3.8{\times}10^{-4}/K$ in the ferroelectric temperature region ($45^{\circ}C{\sim}65^{\circ}C$) and $6.0{\times}10^{-4}/K$ in the phase transition temperature region ($65^{\circ}C{\sim}85^{\circ}C$), which is a larger than optical silica-fiber and PMMA. The resonance transmission peak of P(VDF-TrFE) with the variation of temperature showed hysteretic variation and the phase transition temperature of the polymer in heating condition was higher than in the cooling condition. The elimination of the hysteretic phase transition of P(VDF-TrFE) is necessary for practical applications of optical devices.

Corrosion Resistance of Cr-bearing Rebar in Concrete Subjected to Carbonation and Chloride Attack (중성화와 염해의 복합 열화 환경하의 콘크리트 내에서의 Cr강방식철근의 방식성)

  • Tae, Sung-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.3
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    • pp.115-122
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    • 2006
  • Ten types of steel bars having different Cr contents were embedded in concretes with chloride ion contents of 0.3, 0.6, 1.2, and $2.4kg/m^3$ to fabricate specimens assuming such deteriorative environments. After being carbonated to the reinforcement level, these concretes were subjected to corrosion-accelerating cycles of heating/cooling and drying/wetting. The time-related changes in the corrosion area and corrosion loss of the Cr-bearing rebars were then measured to investigate their corrosion resistance. The results revealed that in a deteriorative environment prone to both carbonation and chloride attack, corrosion resistance was evident with a Cr content of 7% or more and 9% or more in concretes with chloride ion contents of 1.2 and $2.4kg/m^3$, respectively.

Numerical Study of the Performance Characteristics of a Cascade Heat Pump Water Heater at Low Ambient Temperatures (저온 외기조건에서 케스케이드 급탕열펌프의 성능특성에 관한 해석적 연구)

  • Song, Jaehyun;Jung, Haewon;Park, JaeWoo;Kang, Hoon;Kim, Yongchan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.5
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    • pp.225-232
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    • 2013
  • Heat pump systems have been widely adopted in buildings for cooling and heating, due to their higher energy efficiency. Recently, the demand for hot water supply from the heat pump system has been increasing. To increase the water supply temperature with higher system efficiency and reliability, a heat pump water heater adopting cascade cycle was investigated in this study. The cascade heat pump water heater consisted of a low-stage cycle using R410A, and a high-stage cycle using R134a. A simulation program for the cascade heat pump water heater was developed, and verified by comparison with experimental data. The performance of the cascade heat pump water heater was optimized, by varying the compressor rotating speeds of the low- and high-stage cycles. At low ambient temperatures, the performance of the cascade cycle was compared with that of the single-stage cycle. The system efficiency of the cascade cycle was higher than that of the single-stage cycle, showing a lower compression ratio and compressor discharge temperature.

A Comparison of Performance on the Orthogonal and Refraction Heat Exchanger Shape in Air Ventilation System (환기시스템의 굴절 및 평판형 열교환기 형상에 따른 성능비교)

  • Hyeon, Hyeong-Ho;Jeong, Byeong-Ho;Kim, Ji-won;Lee, Kang-yeon
    • Journal of the Korea Convergence Society
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    • v.10 no.7
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    • pp.281-287
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    • 2019
  • Application of heat recovery system applying air supply and cexhaust ventilation device essential in energy management system for the optimum ventilation system utilization and energy saving. This is a key element of infrastructure technology for high-efficiency energy buildings, because it can save heating and cooling energy in winter and summer. In this paper, heat transfer efficiency was simulated using paper, plastic, and aluminum materials that was examined to compare heat exchanger performance under uniform flow conditions. We tested heat transfer efficiengy according to the shape of two of that, one is orthogonal and the other is refraction shape. Based on the simulation results, it is expected to contribute to the production of high performance heat exchanger with heat transfer performance and pressure loss.

How Supernovae Ejecta Is Transported In A Galaxy: DependenceOn Hydrodynamic Schemes In Numerical Simulations

  • Shin, Eun-jin;Kim, Ji-hoon
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.2
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    • pp.48.4-48.4
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    • 2019
  • We studied the metal-distribution of isolated Milky-way mass galaxy using various hydrodynamic solvers and investigated the difference of the result between AMR and SPH codes. In particle-based codes, physical quantities like mass or metallicity defined in each particle are conserved unless being injected explicitly by the effect of the supernova, whereas in the Eulerian codes the diffusion is simply accomplished by hydro-equation. Therefore, without including explicit physics of diffusion on the SPH- codes, the metal mixing in the galaxy or CGM only can be accomplished by the direct motion of the particles, however, the standard-SPH codes depress the instability of the turbulent fluid mixing. In this work, we simulated under common initial conditions, common gas-physics like cooling-heating models, and star-formation feedback using ENZO(AMR) GIZMO and GADGET-2 codes. We additionally included a metal-diffusion algorithm on the SPH-codes, which follows the subgrid-turbulent mixing model investigated by Shen et al. (2010) and compared the effect of the metal-outflow on the halo region of the galaxy in different hydro-solvers. We also found that for the implementation of the diffusion scheme in the SPH-codes, the existence of a sufficient number of the gas-particles, which is the carrier of the metals, is necessary. So we tested a new initial condition for proper implementation of the diffusion scheme on the SPH simulations. By comparing the metal-contamination of the circumgalactic medium with different hydrodynamics models, we quantify the diffusion strength of AMR codes using diffusion parameterization of the SPH codes and also suggest the calibration solutions in the different behavior of codes in metal-outflow.

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Counting People Walking Through Doorway using Easy-to-Install IR Infrared Sensors (설치가 간편한 IR 적외선 센서를 활용한 출입문 유동인구 계측 방법)

  • Oppokhonov, Shokirkhon;Lee, Jae-Hyun;Jung, Jae-Won
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2021.10a
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    • pp.35-40
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    • 2021
  • People counting data is crucial for most business owners, since they can derive meaningful information about customers movement within their businesses. For example, owners of the supermarkets can increase or decrease the number of checkouts counters depending on number of occupants. Also, it has many applications in smart buildings, too. Where it can be used as a smart controller to control heating and cooling systems depending on a number of occupants in each room. There are advanced technologies like camera-based people counting system, which can give more accurate counting result. But they are expensive, hard to deploy and privacy invasive. In this paper, we propose a method and a hardware sensor for counting people passing through a passage or an entrance using IR Infrared sensors. Proposed sensor operates at low voltage, so low power consumption ensure long duration on batteries. Moreover, we propose a new method that distinguishes human body and other objects. Proposed method is inexpensive, easy to install and most importantly, it is real-time. The evaluation of our proposed method showed that when counting people passing one by one without overlapping, recall was 96% and when people carrying handbag like objects, the precision was 88%. Our proposed method outperforms IR Infrared based people counting systems in term of counting accuracy.

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An Experimental and Numerical Analysis on Performance Comparison of a Trigeneration Desiccant System and Conventional Air-conditioning System (Trigeneration 제습공조시스템과 일반공조시스템의 성능 비교 실험 및 수치해석)

  • Kim, Hyoung-Tae;Chae, Jungmin;Cho, Young-Ah;Park, So-jin;Song, Geun-Soo
    • Journal of the Korean Institute of Gas
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    • v.22 no.3
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    • pp.32-37
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    • 2018
  • Recently, the distributed power generation market using natural gas is expected to expand gradually according to the government's future energy conversion policy. Distributed power generation means small power generation source near the power demand site, which has the advantage of reducing the construction costs of the transmission and distribution infrastructure, operating cost and power loss. A typical example of distributed generation using natural gas is the trigeneration system. In this study, we conducted a basic study on the performance analysis of trigeneration desiccant system for dehumidifying / cooling / heating in the air conditioner room by using the cold and engine waste heat energy generated in the trigeneration system. It shows that the system efficiency increases and the energy consumption decreases as the temperature difference between the inlet and outlet of the trigeneration system increases compared with the general air conditioning system.

Research on Heat and Mass Transfer Coefficient in the Packing Layer With a Solar Desiccant Heating/Cooling System (태양열 데시컨트 냉난방시스템 중 충진층에 있어서의 열 물질전달에 관한 연구)

  • Yohana, Eflita;Choi, Kwang-Hwan;Kim, Bu-Ahn;Kim, Dong-Gyu;Paek, Ki-Dong;Kim, Ji-Won
    • Journal of the Korean Solar Energy Society
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    • v.26 no.3
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    • pp.17-24
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    • 2006
  • 최근에 에너지절약 차원에서 종래의 공조방식을 대신할 새로운 냉난방시스템 개발이 요구되고 있는데, 본 논문에서는 태양열 집열기를 이용하는 데시컨트 시스템 중 제습역할을 실질적으로 담당하는 제습기의 충진층 부분에서의 열 및 물질전달에 관한 일련의 해석 결과를 발표하고 있다. 제습과정에서 액체흡수제는 충진층에서 열 뿐만 아니라 물질전달을 수반하게 되는데, 이 결과 건물에 냉방 및 난방효과를 가져다 준다. 따라서 이 충진층의 최적 설계가시스템의 효율을 극대화하기 위해서는 무엇보다도 중요한데, 이를 위해서는 충진층에서의 열 및 물질전달 양상을 규명하여야 한다. 따라서 금번 실험에서는 공기와 액체흡수제와의 접촉면적을 넓히기 위해서 충진재로써 3cm(직경) ${\times}$ 3cm(높이)인 시판중인 플라스틱 재질을 사용하고, 실질적으로 40cm(너비)${\sim}$40cm(깊이)${\times}$40cm(높이)의 충진층을 직접 제작하여 실험을 행하였다. 그 결과, 공기측 열 및 물질전달 계수는 공기 온도와 밀접한 관계를 갖고 있으며, 또한 물질전달계수는 열전달계수와 같은 경향을 보이고 있음을 알 수 있었다.