• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.41-45
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• 2010

The physical properties of DME(Dimethyl Ether) are very similar to LPG and well-mixed. As cetane number of DME is similar to diesel fuel that can replace diesel fuel and alternative energy. DME is a clean energy source that can be manufactured from various raw materials such as natural gas, CBM(Coal Bed Methane) and biomass. DME has no carbon-carbon bond in its molecular structure and its combustion essentially generates no soot as well as no SOx. The development of DME process in KOGAS have 4 section. First, syngas section can be manufactured various syngas ratio. This completes the tri-reforming process for the synthesis gas ratio of approximately 4.0 to 1.0 range can be adjusted. Second, $CO_2$ is removed from the $CO_2$ removal section of about 92~99%, so the maximum concentration of $CO_2$ entering the DME synthesis reactor should not exceed 8%. Third, in the DME synthesis section, if the temperature of DME reactor increases, the activity of DME catalyst increased. but for the long-term activity is desirable to maintain the proper temperature. Finally, the purity of DME in the DME purification section is over 99.6%.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.7
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• pp.387-394
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• 2016

Commercial 28 algae removal technologies that have been applied in domestic rivers and lakes with green tide were investigated, analyzed and classified. The classification of algae removal technologies was based on the three criteria (i.e., principle, flow rate of water body, and application period). Also, algae removal technologies were evaluated in terms of cost effectiveness, field applicability, effect durability, and eco friendliness. From the analysis results, technologies using physical, chemical, biological, and convergent controls were 32.2%, 25%, 21.4%, and 21.4%, respectively. The 75% of technologies have been applied to stagnant water body (${\leq}0.2m/s$). Also, algae harvesting ship with dissolved air flotation, conveyor belt and filtration processes and natural floating coagulant were found to have better field applicability, compared to other technologies. However, proper algae removal technology in specific rivers and lakes should be chosen after the evaluation of long-term pilot scale field test. Also, development of energy and resource recovery technologies from algae biomass is warranted.

• Journal of Biosystems Engineering
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• v.9 no.1
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• pp.62-70
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• 1984

가축배설물(家畜排泄物)의 콤포스트화(化) 작업(作業)의 공학적(工學的)인 국면(局面)은 축산(畜産) 경영(經營)의 축산물(畜産物) 생산성(生産性), 에너지 보전(保全), 공해방지(公害防止)와 분뇨처리(糞尿處理)의 노력(勞力) 절약(節約)에 긴밀(緊密)한 관계(關係)가 있다. 그러나 우리나라에 있어서 축산업(畜産業)의 사양(飼養) 규모(規模)와 두수(頭數)는 매년(每年) 증가(增加)하고 있는 경향(傾向)인바 전통적(傳統的)인 가축(家畜) 배설물(排泄物) 처리(處理) 및 재이용(再利用) 과정(科程)에서 발생(發生)되는 문제점(問題點)에 대(對)한 연구(硏究) 자료(資料)가 없고 특(特)히 콤포스트화(化) 작업(作業)이 원시적(原始的)이므로 개선(改善) 확립(確立)이 절실(切實)히 요구(要求)되는 실정(實定)이다. 본(本) 연구(硏究)의 목적(目的)은 가축(家畜) 분뇨(糞尿)의 콤포스트화(化) 작업(作業) 과정(科程)에서 공학적(工學的)인 제(諸) 문제점(問題點)을 조사(調査) 분석(分析)하여 현상(現狀)을 평가(評價)하고 개선(改善) 방안(方案)을 모색(摸索)하기 위한 기본자료(基本資料)를 제공(提供)하고져 수행(遂行)하였다. 이에 관한 조사(調査)와 분석(分析) 결과(結果)를 요약(要約)하면 다음과 같다. 1. 축산농가(畜産農家)의 가축(家畜) 배설물(排泄物) 처분(處分) 방법(方法)은 대부분(大部分)이 자연건조(自然乾燥), 퇴적(堆積), 혐기적(嫌氣的)인 고형(固形) 또는 액상(液狀) 퇴비화(堆肥化)에 의하여 실시(實施)되고 있었으며 가축분뇨(家畜糞尿)로 인(因)한 공해(公害)는 심각(深刻)하다는 것을 알 수 있었다. 2. 호기성(好氣性) 야적(野積) 콤포스트의 통기작업(通氣作業)은 트랙터에 부착(附着)되어진 전후(前後) 작동식(作動式) 로우더가 바람직하다. 3. 농축산(農畜産) 폐기물(廢棄物)의 콤포스트화(化) 작업(作業)은 축산농가(畜産農家)를 중심(中心)으로 한 콤포스트 센타에서 전체 농가(農家)가 지방(地方) 증진(增進)과 오염(汚染) 방지(防止)를 하기 위해 참여(參與)하여 완전(完全) 공동(共同) 이용(利用) 체계에 따라 일관성(一貫性)있게 수행(遂行)되어야 한다. 4. 호기성(好氣性) 야적(野積) 콤포스트 작업(作業)은 다른 방법(方法)에 비하여 운영비(運營費)가 적게 들어 영세적(零細的)인 축산업(畜産業)의 경우(境遇)에 가장 적당(適當)하고 공해(公害)를 방지(防止)함으로서 한국(韓國) 축산농가(畜産農家)의 콤포스트화(化) 시설(施設)로 전망(展望)이 밝다고 판단(判斷)된다.

• Journal of the Korean association of regional geographers
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• v.13 no.1
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• pp.32-42
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• 2007

In Sagye coast of Andeok-myeon, southwestern Jeju, shore platform of noncohesive Hamori Formation, marine terrace deposit of round gravels, coastal dune composed of shell sand and volcanic sand, and back lake are linked closely with each other. In this paper, the formation process of Sagye coastal geomorphic system analysed by using OSL dating method is as follows: Firstly, Hamori Formation is a horizontal stratum filed up of tuff reworked by submarine volcanic eruption during 3$\sim$7.6 ka BP. Hollow at the boundary between Hamori Formation' flat and Kwangheak Basalt's gentle slope become a back lake when block is appeared over the sea level by uplift. Secondly, while Hamori Formation was laid below sea level, gravels which had been broken and abraded at southwestern rocky coast composed of Kwangheak basalt or been transported through the small stream from adjacent hillslope were deposited in rapid flow environment. Thirdly, deposition of round gravels was ceased by earth uplift, and shore platform was constructed by abrasion process of energy of swash moving forward. As altitude of shore platform is equal to high tidal level of spring tide, compared it with present high tidal level of study area, earth is uplifted about 105m since shore platform was formed. Fourthly, much sandy sediments transported from offshore bottom covered shore platforms and marine terrace deposits. Lighter sediments among sandy sediments was blown to back, formed secondary sand dune since about 500 year.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.233-239
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• 2013

Recently, a number of wind turbines are being installed due to the increase of interest in renewable, environment-friendly energy. Especially, an offshore wind turbine is being watched with keen interest in that it has no difficulty in securing a site and can get high quality of wind, as compared with a wind turbine on land. The offshore wind turbine is transferred to and installed on the site by an offshore floating crane after it was made in a factory on land such as shipyard. At this time, it is important to secure the safety of the turbine because of its huge size and expensive cost. Thus, a dynamic analysis of the offshore wind turbine which is connedted with the offshore floating crane was performed based on the multibody systems dynamics in this study. As a result. it is shown that the analysis can be applied to verify the safety of a method for the transportation and installation of the offshore wind turbine suspended by the crane.

• Journal of The Korean Association For Science Education
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• v.35 no.3
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• pp.509-521
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• 2015

Argumentation is a social and collaborative dialogic process. A large number of researchers have focused on analyzing the structure of students' argumentation occurring in the scientific inquiry context, using the Toulmin's model of argument. Since SSI dialogic argumentation often presents distinctive features (e.g. interdisciplinary, controversial, value-laden, etc.), Toulmin's model would not fit into the context. Therefore, we attempted to develop an analytical framework for SSI dialogic argumentation by addressing the concepts of 'discourse clusters' and 'discourse schemes.' Discourse clusters indicated a series of utterances created for a similar dialogical purpose in the SSI contexts. Discourse schemes denoted meaningful discourse units that well represented the features of SSI reasoning. In this study, we presented six types of discourse clusters and 19 discourse schemes. We applied the framework to the data of students' group discourse on SSIs (e.g. euthanasia, nuclear energy, etc.) in order to verify its validity and applicability. The results indicate that the framework well explained the overall flow, dynamics, and features of students' discourse on SSI.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.69-78
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• 2003

In this study, the energy conversion equipment from the radiation energy to mechanical energy by using n­pentane as the operating fluid was constructed and the performance to pump the water was tested for the utilization of solar powered water pump. The equipment was designed optimally, after the theoretical analyses of the water pumping head and water quantity per cycle were done. The pentane vapour temperature in the condenser and the temperature of the outlet water from the condenser became lowered and the heat transfer rate became higher with decreasing the water inlet level to the condenser. The temperature difference between the condenser and the water tank was significant. Therefore, the distance between the water tank and condenser was recommended to be shorten and the diameter of their connecting pipe was recommended to be narrow in order to reduce the resistance of the fluid passage and improve the heat transfer rate. The amount of water pumped was 1.6­2.4 liters. Mass flow rate of the cooling water became lowered when the cooling water pipe was prolonged from the condenser to improve the heat transfer rate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.504-511
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• 1990

Weather data acquisition and potential evapotranspiration (PET) calculation procedure were investigated to support the agricultural development efforts in the mid-altitude mountainous region of Cheju Island. Automated weather stations (AWS) were installed at two points representing the east and the west of the study area. A personal computer was employed to collect the near-real time weather data from AWS through the public telephone line. Hourly data were available for solar radiation, air and soil temperature, relative humidity, wind speed and direction, and precipitation. Based on the data for the month of June 1989, daily climatic features were comparatively analyzed for the two areas and the Penman equation was used to calculate PET. Air temperature was higher by 1 to 2 degree C in the east due mainly to the higher solar radiation and partly to the Fohn effect caused by the daytime southwesterly blowing over Mt. Halla. Diurnal march of soil temperature lagged by 4 hours behind that of air temperature and the diurnal range for 10cm subsurface soil was 3 degree C. Wind was consistently stronger and a marked sea-land breeze circulation was detected in the west. Calculated PET values were higher in the east by 6% than in the west. Overall values from the east and the west of the mid-altitude mountainous region were higher by 30% than those of the coastal region, which were estimated from the Class A Pan evaporation measured by the Korea Meteorological Service Offices.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.201-212
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• 2016

A Wind resource assessment and optimal micrositing of wind turbines were implemented for the development of an onshore wind farm of 30 MW capacity on Gadeok Island in Busan, Republic of Korea. The wind data measured by the automatic weather system (AWS) that was installed and operated in the candidate area were used, and a reliability investigation was conducted through a data quality check. The AWS data were measured for one year, and were corrected for the long term of 30 years by using the modern era retrospective analysis for research and application (MERRA) reanalysis data and a measure- correlate-predict (MCP) technique; the corrected data were used for the optimal micrositing of the wind turbines. The micrositing of the 3 MW wind turbines was conducted under 25 conditions, then the best-optimized layout was analyzed with a various wake model. When the optimization was complete, the estimated park efficiency and capacity factor were from 97.6 to 98.7 and from 37.9 to 38.3, respectively. Furthermore, the annual energy production (AEP), including wake losses, was estimated to be from 99,598.4 MWh to 100,732.9 MWh, and the area was confirmed as a highly economical location for development of a wind farm.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.24-31
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• 1997

2매의 금속을 맞대어 그 한 쪽에 접촉면과 평행하게 고주파진동을 가하면 단 시간에 접합된다. 이공정을 초음파 용접이라고 하며 그 물리적인 본질은 아직 불분명 하지만, 첫째로는 강한 마찰에 의해 금속 자유면의 산화물층이 제거되기 때문이라는 점과 둘째로는 마찰에 의해 금속 표면이 강하게 가열되어 이에 따른 연화에 의해 접합 이 된다고 하는 점이다. 그러나 이와 같이 가열된다고 하더라도 가열은 표면부에만 국한되고 다른 부분은 가열되지 않는다. 따라서 초음파용접은 냉간접합이라고도 한다. 또 가압력과 진동에 의한 힘이 동시에 작용하기 때문에 용접할 면을 미리 청정하게 할 필요는 없고 용접전의 단계에서 자연적으로 청정화가 이루어진다고 하는 사실이 간접 적으로 증명되고 있다. 초음파 용접(Ultrasonic welding)의 특징을 요약하면 고상용접 의 일종으로서 용접중에 국부적으로 고주파 진동에너지와 압력을 가하여 용접하는 방법이다. 이 때 모재를 용융시키지 않고 건전한 야금학적 결합부가 얻어진다는 데에 큰 특징이 있다. 또한 초음파용접은 다른 용접법에 비해 경제성이 매우 높고, 초음파 용접에 필요한 출력이 전기아크 용접에 필요한 출력의 5 - 10%로 충분한 경우가 많다. 초음파 용접은 통상의 방법으로는 용접하기 어려운 동종 금속이나 이종 금속의 용접에 널리 사용된다. 이 용접법은 반도체, 미세회로, 전기 접점의 형성에 대한 생산기술 로서 사용되고 있는데 소형 모터, 알루미늄 박의 가공, 알루미늄 합금의 조립 등에 이용되고 있다. 한편 최근에는 자동차, 우주항공산업 분야의 구조제 용접용으로도 채용되고 있다.출함이 바람직하다.분비되는 배설-분비 항원의 자극과 깊은 관계가 있음을 알 수 있었다.넌트 명세서를 대한 XML DTD(Document Type Definition)를 정의하고, HTML 기반 검색 방법과 XML 기반 검색 방법에 대한 컴포넌트 검색 성능을 비교한다.따라 NO 생산 및 세포독성이 증가하였고. NO 생산을 저하시키는 약제들은 활성화된 복강 대식세포 및 RAW264.7 세포에 의한 질편모충에 대한 세포독성을 현저히 감소시키는 것으로 보아 NO는 질편모충에 대한 대식세포의 숙주 방어기전에서 중요한 역할을 감당할 것으로 생각된다.nction index) 와 최대개구시 동통의 정도는 시술전과 시술 4주후간에 유의한 차이가 관찰되었다.피부온도는 검사자간에는 특정부위에 따라 다소 차이가 있을 수 있으나 일반적으로 높은 재현성을 보여줌으로서 향후 교근 및 측두근의 임상연구 평가에 피부온도조사는 도움이 되리라 사료된다. lactobacilli의 양은 peroxidase system을 함유하거나(p < 0.01) 함유하지 않은(p < 0.05) 치약을 사용한 군 모두에서 양치전에 비해 유의성있게 감소하였다. 6. 양치후 30분에 채취한 구강건조증 환자의 자극성 전타액내 S. mutans 양은 peroxida system을 함유한 세치제를 사용한 군에서 대조군에 비해 유의성있게 낮았다(p < 0.05). 7. 양치후 30분에 채취한 구강건조증 환자의 자극성 전타액내 lactobacilli양은 peroxidase system을 함유한 세치제를 사용한 군에서 대조군에 비해 상대적으로 낮게 나타났으나(p = 0.067)