• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.4
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• pp.12-21
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• 2022

Steam assisted gravity drainage(SAGD) is a process that drills well in the underground oil sands layer, injects hightemperature steam, lowers the viscosity of buried bitumen, and recovers it to the ground. Recently, direct contact steam generator(DCSG) is being developed to maximize steam efficiency for SAGD process. The DCSG requires high technology to achieve pressurized combustion and steam generation in accordance with underground pressurized conditions. Therefore, it is necessary to develop a combustion technology that can control the heat load and exhaust gas composition. In this study, process analysis of high-pressurized DCSG was conducted to apply oxygen enrichment technology in which nitrogen of the air was partially removed for increasing steam production and reducing fuel consumption. As the process analysis conditions, methane as the fuel and normal air or oxygen enriched air as the oxidizing agent were applied to high-pressurized DCSG process model. A simple combustion reaction program was used to calculate the property variations for combustion temperature, steam ratio and residual heat in exhaust gas. As a major results, the steam production efficiency of DCSG using the pure oxygen was about 6% higher than that of the normal air due to the reducing nitrogen in the air. The results of this study will be used as operating data to test the demonstration device.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1682_1683
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• 2009

터빈으로 유입되는 증기유량을 제어하여 속도를 제어하는 시스템 즉, 터빈제어시스템은 발전소에서 주요한 설비 중에 하나이다. 터빈제어시스템의 검증된 제어 알고리즘 기능은 발전소 계통의 안정성 증진 및 전력 생산의 품질을 향상시키고 경제적 손실을 경감시킨다.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.613-620
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• 2005

There are some problems in utilizing recycled concrete aggregate go structural use because of the difficulties concerning about quality control and durability. It seems to be possible to utilize recycled concrete aggregate for making concrete products because quality control of concrete products is easier than ready-mixed concrete, but there are little studies about the properties of the steam-cured recycled aggregate concrete. In this study, various tests were performed such as compressive strength, flexural strength, splitting tensile strength, bonding strength and chloride ion penetration test to evaluate the effect of substitution of recycled concrete aggregate. The results of strength test showed that the concrete strength decreased with the increase of the substitution ratio of recycled concrete aggregate, but it was in the reasonable range and almost equal to that of normal concrete below the substitution ratio of $50\%$. On the other hand, strength test of furnace slag cement concrete shows that the strength of recycled concrete with furnace slag cement under curing condition lower than that of recycled concrete with ordinary portland cement under same condition. From the result of this study, it can be concluded that recycled concrete aggregate is able to be utilized for structural use but substitution ratio should be decided with care in each case. The result of this study could be used as the basic data for the structural use of recycled concrete aggregate.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.141-148
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• 2017

This study is experimentally investigated the effects of various steam curing parameters on the early-age compressive strength development of high strength concrete (over 40 MPa) in the precast plant production. High strength concrete are used only ordinary portland cement (type I) and water-cement ratio selected 3cases (25%, 35% and 45%). Also, steam curing parameters are as followings ; (1) Preset period 2cases (3 hours and 6 hours) (2) Maximum curing temperature 3cases ($45^{\circ}C$, $55^{\circ}C$ and $65^{\circ}C$) (3) Maintenance time of curing temperature 3cases (4 hours, 6 hours and 8 hours) (4) Maximum rate of heating and cooling $15^{\circ}C$/hr. Initial setting time and adiabatic temperature rising ratio of these concrete according to water-cement ratio are tested before main tests and examined the compressive strength development for the steam curing parameters. Also compressive strength are compared with optimum steam curing condition and standard curing at test ages. As test results, the optimum steam curing conditions for high strength concrete(over 40 MPa) are as followings. (1) Preset period ; over initial setting time of concrete (2) Maximum curing temperature ; bellow $55^{\circ}C$ (3) Maintenance time of curing temperature ; bellow 6hours. Also strength development of steam curing concrete show in the reversed strength at 28 days. It is to propose an efficient steam curing condition for high strength concrete in the precast method.

• Korean journal of food and cookery science
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• v.29 no.4
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• pp.387-398
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• 2013

Seasoned soy sauce is one of the popular seasoning sauces added to the Korean traditional foods such as Bulgogi, Galbi. However, industrially processed sauces have poor sensory quality because of heating treatment for sterilization. The purpose of this study was to develop seasoned soy sauce having fresh taste and good quality by applying superheated steam (SHS) and high hydrostatic pressure (HHP) technologies. To maintenance the sauce qualities, food materials such as apple, onion, and garlic were pretreated with SHS (heater $100^{\circ}C$, steam $280^{\circ}C$, 30 s~1 min 30 s) before mixing with other ingredients. During storage of 7 days, color, pH, and browning potential of SHS treated samples (apple, onion and garlic) did not change and also polyphenol oxidase was inactivated (p<0.05). The seasoned soy sauce including SHS treated materials was sterilized by thermal process ($85^{\circ}C$, 30min) or non-thermal process, HHP (550 MPa, $5{\sim}10^{\circ}C$, 3 min). In SHS+HHP treated sauce, salinity, sugar contents, lightness, viscosity did not change (p<0.05), and total viable cell counts were detected below 4 log cycle at $5^{\circ}C$ for 30 days. E.coli and B.cereus are not determined in all samples. In sensory evaluation, Bulgogi prepared with SHS+HHP treated sauce was more acceptable than others.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.663-665
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• 2007

생산시설에서의 소음원은 여러 가지가 있으나 증기 방출시 발생되는 소음은 대기 중에 직접 노출되기 때문에 증기 방출시 소음저감을 위한 사이렌서의 설치가 필요하다. 스팀 사이렌서는 습기와 고온에 항상 노출되기 때문에 일반적인 흡음 및 차음재료의 사용에 제한이 있다. 본 연구에서는 스틸 울과 스틸 타공판으로 구성된 사이렌서와 사이렌서를 둘러싸는 외부 용기로 구성된 스팀 사이렌서를 대상으로 소음저감성능을 평가하였다. 스팀 방출시 소음 저감 성능을 평가하여야 하지만 사이렌서 내부에서 스팀이 방출되는 조건에서의 실험에 어려움이 있어 스팀사이렌서의 내부에 라우드 스피커와 마이크로폰을 설치하여 스팀사이렌서 내부에서 발생되는 음압레벨을 측정하였다. 또한 소음이 표면에서 1m 이격된 지점에서의 소음레벨을 측정하여 소음저감성능을 평가하였다. 소음 저감성능 평가 결과 500 Hz 이상 주파수 범위에서 약 40 dB이상의 소음저감성능을 확인하였다.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1883-1884
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• 2006

원자력발전소는 원자로의 증기발생기에서 생산한 증기의 압력으로 터빈발전기를 돌려서 발전을 하고 있다. 터빈속도를 제어하는 디지털식 터빈 조속기는 마이크로프로세서를 기반으로 하는 디지털식 제어기가 널리 사용하고 있으며, 조속기에 사용되는 제어기는 빠른 제어 응답성과 높은 신뢰성을 요구하고 있으므로 제어 프로그램의 실행속도에 따라서 제어의 특성과 질이 좌우 될 수 있다. 디지털식 제어기는 제어프로그램을 순차적으로 반복 실행하며, 중요도에 따라서 몇 개의 그룹으로 나누어 실행 주기를 달리함으로써 제어기의 과도한 부하율을 피하고 있다. 이렇게 함으로써 빠른 제어 응답성과 시스템 안정성을 모두 만족하는 실행주기로 최적화하는 과정이 필요하여 본 시험을 하였으며 이러한 제어특성을 사전에 확인하여 원자력발전소의 아날로그식 조속기를 디지털식 조속기로 개선을 하고자 시험한 사례를 소개한다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.107-112
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• 1996

In this paper it is proposed a new approach to the development of the automatic vision system to examine and repair the steam generator tubes at remote distance. In nuclear power plants workers are reluctant of works in steam generator because of the high radiation environment and limited working space. It is strongly recommended that the examination and maintenance works be done by an automatic system for the protection of the operator from the radiation exposure. Digital signal processors are used in implementing real time recognition and examination of steam generator tubes in the preposed vision system, Performance of proposed digital vision system is illustrated by experiment for similar steam generator model.

• Journal of the KSME
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• v.29 no.1
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• pp.12-13
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• 1989

분쇄도구는 점차수차, 풍차 그리고 증기기관이란 동력기술과 맞물려 제분공정이 대규모화되어 지배자는 이를 독점, 집중화시켜 마침내 공장제도의 원형이 이루어졌던 것이다. 여기서 우리는 wind mill, water mill, rolling mill, miller, milling M/C 등 단어가 뜻하듯 단순히 "제분하는 기계" 뿐만 아니라 "자연력으로 구동되는 기계설비를 사용하였던 모든 Manufacture"라는 것을 공통어 밀(mill)에서 엿볼 수가 있다. James Watt의 증기기관이 실용 중에도 한동안 수차는 산 업 여러 분야에서 동력원으로 자리를 지켜 왔지만 현재는 획기적으로 성능이 좋은 Francis, Pelton, 및 Ossberger 수차가 상업발전소에서 쉬지 않고 돌아가고 있다. 통차, 동미차, 번차, 수대, 연애, 파쇄 등 전통적인 수차와 석구가 기본이 되어 분명히 근세 생산기계설비를 발명케 하였고 동력원으로서 화려한 전성기를 누렸다. 지금은 역사속에 잊혀져 가지만 우리는 시골 산간에서 돌아가는 물레방아의 수연한 고태를 볼 때면 민속문화학, 그리고 기술사적 측면에서 문화재로서의 명맥을 기려 잘 보존할 의무가 절실하다고 생각한다. 보존할 의무가 절실하다고 생각한다.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.1-10
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• 2003

Pressurized fluidized bed combustion unit is operated at pressures of 1~1.5 MPa with combustion temperatures of 850~87$0^{\circ}C$. The pressurized coal combustion system heats steam, in conventional heat transfer tubing, and produces a hot gas supplied to a gas turbine. Gas cleaning is a vital aspect of the system, as is the ability of the turbine to cope with some residual solids. The need to pressurize the feed coal, limestone and combustion air, and to depressurize the flue gases and the ash removal system introduces some significant operating complications. The proportion of power coming from the steam : gas turbines is approximately 80:20%. Pressurized fluidized bed combustion and generation by the combined cycle route involves unique control considerations, as the combustor and gas turbine have to be properly matched through the whole operating range. The gas turbines are rather special, in that the maximum gas temperature available from the FBC is limited by ash fusion characteristics. As no ash softening should take place, the maximum gas temperature is around 90$0^{\circ}C$. As a result a high pressure ratio gas turbine with compression intercooling is used. This is to offset the effects of the relatively low temperature at the turbine inlet.