• 한국농공학회논문집
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• 제62권2호
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• pp.17-29
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• 2020

The objective of this study was to find an optimum methane yield condition in anaerobic digestion of sewage sludge with microwave pretreatment. The pretreatment process was carried out using a lab scale industrial microwave unit (2,450 MHz frequency). The digestion efficiency of pretreated sludge was evaluated by biochemical methane potential (BMP) test. Box-Behnken design and Response Surface Analysis (RSA) were applied to determine the optimal combination of sludge mixing ratio (0 to 100%), power (400 to 1600 W), holding time (0 to 10 min) and pretreatment temperature (60 to 100℃). BMP test results showed that Volatile Solid (VS) removal efficiency was up to 48% at a condition of 0% for mixing ratio, 1600 W for power, 5 min for holding time, and 80℃ for pretreatment temperature. Methane production was up to 832.3 mL/g VS_removed at a condition of 50% for mixing ratio, 1000 W for power, 5 min for holding time, and 80℃ for pretreatment temperature. The results of the variance analysis (ANOVA) showed that the p-value of the power and pretreatment temperature among the independent variables were significant (p<0.05), and in particular, the pretreatment temperature significantly affected on the solubilization and methane production. The optimum condition for the maximum methane yield (847 mL/g VS_removed) was consist of 38.4% of mixing ratio, 909.1 W of power, 4.1 min of holding time, and 80℃ of temperature within the design boundaries.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.403-407
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a greenhouse culture facility for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex in Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• 신재생에너지
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• 제1권2호
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.485-493
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• 2016

Recently submarine and unmanned underwater vehicle (UUV) are equipped with a fuel cell system as an air independent propulsion system. Methanol fuel processor can efficiently supply the hydrogen to the fuel cell system to improve the ability to dive. This study investigated the optimal conditions of the methanol fuel processor that may be used in the closed environment. For this purpose, the numerical model based on Gibbs minimization equation was established for steam reformer and three exhaust gas burners. After simulating the characteristics of steam reformer according to the steam-to-carbon ratio (SCR) and the pressure change, the SCR condition was able to narrow down to 1.1 to 1.5. Considering water consumption and the amount of heat recovered from three burners, the optimum condition of the SCR can be determined to be 1.5. Nevertheless, the additional heat supply is required to satisfy the heat balance of the methanol fuel processor in the SCR=1.5. In other to obtain additional amount of heat, the combustion of methanol is better than the increased of SCR in terms of system design.

• 상하수도학회지
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• 제20권1호
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• pp.138-146
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• 2006

The characteristics of backwash and concentrate discharges depend upon the quality of the water being treated and the net recovery of the membrane system. This paper is to indicate a design methods on the capacities of residuals treatment facilities in membrane processes for drinking water. We operated a demonstration membrane plant with a recovery rate of 90% for designing G-water treatment plant. We investigated on design parameter (optimum coagulant dosage and surface loading rate etc.) to design efficiently the residuals treatment facilities. The settling test was conducted with 1m columns dosing PACl to kaolin and membrane residuals under the experimental condition that discharge permit was under a 60mg/L. When the quantity of membrane residuals was $1,575m^3/day$, the estimated results for 1st thickener demonstrated the surface loading rate of 14.4m/day, detention time of 5.83hr, available depth of 3.5m.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.423-431
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• 2016

In this study, wing design optimization for long-endurance unmanned aerial vehicles (UAVs) is investigated. The fluid-structure integration (FSI) analysis is carried out to simulate the aeroelastic characteristics of a high-aspect ratio wing for a long-endurance UAV. High-fidelity computational codes, FLUENT and DIAMOND/IPSAP, are employed for the loose coupling FSI optimization. In addition, this optimization procedure is improved by adopting the design of experiment (DOE) and Kriging model. A design optimization tool, PIAnO, integrates with an in-house codes, CAE simulation and an optimization process for generating the wing geometry/computational mesh, transferring information, and finding the optimum solution. The goal of this optimization is to find the best high-aspect ratio wing shape that generates minimum drag at a cruise condition of $C_L=1.0$. The result shows that the optimal wing shape produced 5.95 % less drag compared to the initial wing shape.

• 한국인공지능학회지
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• 제6권1호
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• pp.1-10
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• 2018

Compressed Air is an important energy source used in most factories nowadays. The automation trend using air compressor has been gradually increasing with the interest of the 4th industry in recent years. With the air compressor system, it is possible to construct the device at low cost and easily achieve automation and energy saving. In addition, With trend of FA, miniaturation and light weight manufacturing trend expand their use in the electronics, medical, and food sectors. Research method is to design the technology for the remote control of the following information as USN base. Development of flexible sensing module from real time observation module for fusion of IT technology in compressed air systems, design and manufacture of flexible sensing module, and realiability assessment. Design of real-time integrated management system for observation data of compressed air system - Ability to process observation data measured in real time into pre-processing and analysis data. This study expects unconventionally decreasing effect of energy cost that takes up 60~70% of air compressor layout and operation and maintenance management cost through USN(Ubiquitous Sensor Network) technology by using optimum operational condition from real time observation module. In addition, by preventing maintenance cost from malfunction of air compressor beforehand, maintenance cost is anticipated to cut back.

• 한국지열·수열에너지학회논문집
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• 제11권4호
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• pp.28-34
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• 2015

The groundwater heat pump (GWHP) systems have great potential for heating-cooling system which use annual constant groundwater temperature for heat source. Generally, the performance of GWHP system significantly depends on the geological and hydraulic properties such as hydraulic conductivity, thermal conductivity, soil condition so on. Therefore, in order to use GWHP systems efficiently, it is necessary to analyze the effect of design factors on the system performance. However, there are a few researches on the optimum design method for the open-loop geothermal system. In this research, the design factor in the open-loop geothermal system was analyzed quantitatively for the optimal design method by using numerical simulation. As a result, it was found that the temperature change of heat source depends on the design factor.

• 대한기계학회논문집A
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• 제28권2호
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• pp.109-117
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• 2004

Optimization has been successfully applied to systems with a single discipline. As many disciplines are involved in coupled fashion, MDO (multidisciplinary design optimization) technology has been developed. MDO algorithms are trying to solve the coupled aspects generated from interdisciplinary relationship. In a general MDO algorithms, a large design problem is decomposed into small ones which can be easily solved. Although various methods have been proposed for MDO, the research is still in the early stage. This research proposes a new MDO method which is named as MDOIS (Multidisciplinary Design Optimization Based on Independent Subspaces). Many real engineering problems consist of physically separate components and they can be independently designed. The inter-relationship occurs through coupled physics. MDOIS is developed for such problems. In MDOIS, a large system is decomposed into small subsystems. The coupled aspects are solved via system analysis which solves the coupled physics. The algorithm is mathematically validated by showing that the solution satisfies the Karush-Kuhn-Tucker condition.

• 한국포장학회지
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• 제7권2호
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• pp.19-24
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• 2001

현재 국내에는 통기성 상자의 설계에 관한 기준이 마련되어 있지않아, 통기공으로 인한 상자 압축강도 저하와 통기성 면에서도 좋지 않은 형편이다. 선진 외국과는 물류 및 포장환경이 다르고, 방법에 있어서도 큰 차이가 있기 때문에 외국의 사례를 국내의 포장설계에 적용하는 데는 한계가 있다. 따라서 본 연구는 현재 국내에서 유통되는 통기성 상자에 대한 실태분석과 온 습도 변화에 따른 압축강도 저하와 통기성을 분석하므로써, 통기성 상자의 최적설계를 위한 설계 기준을 마련하고자 수행되었다. 현행 유통되는 통기성 상자의 통기공의 면적 비율은 $1.41{\sim}2.65%$ 였으며, 통기공의 형태, 크기 및 위치가 매우 다양하여, 이로 인한 상자 압축강도 저하율은 $8.5{\sim}20.2%$의 범위에 있었다. 대체로 통기공의 면적비율 보다는 통기공의 형태와 위치가 상자의 압축강도 저하에 미치는 더 중요한 요인으로 분석되었다. 통기공의 면적비율이 클 수록 온도와 상대습도의 평형도달시간은 짧았으며, 온도가 상대습도에 비하여 더 빨리 형평상태에 도달하였으며, 또한 통기공의 면적 비율이 같은 경우, 통기공의 형태에 따른 온도 및 상대습도의 평형도달 시간과 평형도달 온 습도에 있어서는 큰 차이가 없었다.