• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.27-33
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• 2004

The Noise generation mechanisms of propane laminar premixed flames on a slot burner have been studied experimentally. The sound levels and frequencies were measured for various mixture flow rates (velocities) and equivalence ratios. The primary frequency of self-induced noise increases with the mean velocity of mixture as $f{\;}{\propto}{\;}U_f^{1.144}$ and the measured noise level increases with the mixture flow rate and equivalence ratio as $p{\;}{\propto}{\;}U_f^{1.7}$$F^{8.2}$. The nature of flame oscillation and the noise generation mechanisms are also investigated using a high speed CCD camera and a DSRL camera. The repetition of sudden extinction at the tip of flame is evident and the repetition rates are identical to the primary frequencies obtained from the FFT analysis of sound pressure signals. CH chemiluminescence intensities of the oscillating flames were also measured by PMT with a 431 nm(10 FWHM) band pass filter and compared to the pressure signals.

• 한국기계기술학회지
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• 제13권4호
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• pp.85-91
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• 2011

Experimental analysis has been carried out to investigate thermal characteristics of hydraulic system in special vehicles. Hydraulic system performance is largely influenced by oil temperature, and there are considerable performance decline and malfunctions in the system for high temperature conditions caused by heavy load and continuous operation. Transient oil temperature and pressure variation are analyzed and heat generation rates in the several main system parts are compared for various flow rates. With the start of system operation oil temperature gradually increases, and viscosity deceases by about 70% as temperature increases from $20^{\circ}C$ to $80^{\circ}C$. Operation pressure in the hydraulic system decreases with oil temperature, and its variation rate becomes less steep as oil temperature increases. Heat generation rate in hydraulic pump also depends on the oil temperature, and it reaches maximum near $50^{\circ}C$. These results in this study can be applied to optimal design of efficient hydraulic system in special vehicles.

• 토지주택연구
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• 제5권1호
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• pp.41-51
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• 2014

국내 신축 공동주택 건설은 2002년 11% 이상의 증가를 기록한 후 매년 3~4% 대의 꾸준한 증가추세를 보이고 있다. 최근 공공부문의 아파트 신축공사 현장에서 폐기물 분리발주제도에 의한 최초 발주물량과 실제 발생물량의 과다한 차이가 발주자와 수급인 사이에서 빈번하게 논란을 일으키고 있다. 이에 대해서는 현장 환경관리 미흡, 초기 계약물량의 과소 등 다양한 원인이 제기되고 있으며, 특히 건설폐기물 수량 예측에 적용되는 발생원단위 기준에 대한 개정 요구가 갈수록 증가하고 있다. 대부분의 현행 원단위는 2000년대 초에 수립되어 기술 발전에 따라 새롭게 적용되는 자재와 공법으로 인한 폐기물 발생 유형과 수량의 변화를 반영하지 못한다는 문제점을 지니고 있다. 따라서 본 연구는 보다 정밀한 신축아파트 폐기물 발생 원단위를 개발하기 위한 기초작업으로서 현장의 공종별 폐기물 발생 유형과 수량 예측방법을 명확히 하고자 하였다. 이를 위해 2010년에서 2013년 사이에 착공한 신축 아파트 10개 현장의 건축공사 내역서를 확보하고, 건설폐기물 전문가와 현장 폐기물관리 담당자의 의견을 반영하여 각 내역항목에서 발생가능한 폐기물 유형과 실질 할증률을 검토하였다. 본 연구에서 가설공사부터 지급자재부문까지의 건축공사 내역항목별로 정리한 폐기물 발생여부와 유형, 수량예측 시 반영여부, 손실률 등의 자료는 향후 보다 현실적인 데이터에 근거한 간접추계방식의 원단위 개발에 기여할 것이다.

• International Journal of Railway
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• 제5권4호
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• pp.139-143
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• 2012

In Korea, almost 700 industrial parks are under operation. Generally, industrial parks consist of national industrial parks and local industrial parks which are managed by a central government and by local governments respectively. The developing countries such as Korea, China and Vietnam etc. have constructed many industrial parks, which result in the change of land use pattern and also affect future trip demands. Therefore, in estimating traffic demands, it is very important to consider the industrial park development. This study aims to improve the methodology in estimating a freight trip generation rate with the data based on a nationwide commodity freight survey. The result showed that it is desirable to apply freight trip generation rate by the industry sector in estimating freight trip generations and using the production area of firm as an indicator. Specially, the reliability of the rates through a survey could be made sure because a sample rate based on firms in industrial parks was over 25% and the response rate was over 67%. The sample rate and response rate are very superior as compared to surveys conducted in many other countries. Because industrial parks have significant effects on forecasting transportation demand in pre-feasibility studies of transport and logistics projects, it is expected that the accuracy of freight trip demands would be improved through the results of this study.

• 청정기술
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• 제18권3호
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• pp.320-324
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• 2012

본 연구에서는 리튬이온전지의 방전특성에 따른 열발생 속도를 계산하여 전지의 특성을 평가하였다. 이를 위하여 Butler-Volmer 식을 지배방정식으로 하여, 유사 2차원 모델링을 적용하고, 편미분 연산자인 FEMLAB을 이용하여 전산모사를 수행하였다. 전류밀도를 5 $A/m^2$에서 25 $A/m^2$까지 증가시켜 계산을 수행한 결과, 전류밀도가 증가함에 따라 전극표면에서 고체상 리튬의 소모량이 증가되는 것으로 나타났다. 이로 인한 확산제한의 발생시점이 단축되었으며, 동시에 리튬이온전지의 내부 전위가 컷오프 전위에 도달하는 시점에서 열발생 속도가 급격하게 증가되는 현상을 보여주었다.

• International Journal of Korean Welding Society
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• 제1권1호
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• pp.71-77
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• 2001

The characteristics of the fume generation in a flux cored arc welding were investigated using the fume collection chamber developed. The Korean Standard concerning the method for the evaluation of the fume generation rate(FGR) was updated by the evaluation method obtained through this study. It was found that the effect of humidity in the test environment should be considered and the automatic welding method had to be employed for the purpose of the exact evaluation of the fume generation rate. The results showed that the fume generation rate was influenced by the welding parameters. The important factors were the welding current arc voltage, travel speed, and contact tip to work distance(CTWD) that affected the heat input as well as the torch angle and the shielding gas flow rate that influenced the shielding effect. The fume generation rate increased as the heat input increased and the shielding effect decreased. It was also observed that the effect of the welding current is much grater than the other welding parameters.

• 한국가스학회지
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• 제19권6호
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• pp.72-79
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• 2015

천연가스 감압기지에 터보팽창기 감압시스템을 도입하여 천연가스의 감압과정에서 전기에너지를 생산할 수 있다. 터보팽창기의 효율은 천연가스의 유량과 터보팽창기 설계유량의 비에 따라 달라진다. 따라서 터보팽창기로 들어가는 유량을 조절함으로써 감압시스템을 운전하기 위한 최적조건을 결정할 수 있다. 본 연구에서는 두 곳의 저압 정압기지에서 천연가스의 압력이 17.5 bar에서 8.5 bar로 감압될 때 천연가스의 유량에 따라 생산 가능한 전력을 계산하고 계산결과의 비교를 통해 터보팽창기 감압시스템이 최적으로 운전되기 위한 조건을 찾았다. 천연가스의 평균 유량이 크고 유량의 변화가 작을 때 터보팽창기가 효율적으로 운전되었고 터보팽창기의 설계유량은 천연가스의 유량을 가장 많이 포함하는 용량에서 결정되었다. 선정된 두 정압기지에서 회수 가능한 전력생산량은 9 MW(B 기지), 12 MW(D 기지)로 추산되었다.

• 산업기술연구
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• 제17권
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• pp.169-174
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• 1997

This investigation was carried out to study on the generation property, management and seperate collection rate of solid waste in the Gu-Gok Falls. Generation rate of solid waste was 80.785kg/day and unit waste generation rates was $65.55g/day{\cdot}tourist$ one person. Physical component of solid waste were garbage 46%, papers 20%, empty bottles 10%, respectively. A plan is required to decrease generation rate of garbage waste. As result to investigate separated garbage can, papers and can were separated more than 60%. But empty bottles and scrap iron were separated less than 50%. P.E.T, steel can, aluminum can and empty bottles were 20% of total generation rate, and profit of reuse is \700,800/year.

• 한국IT서비스학회지
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• 제22권3호
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• pp.101-118
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• 2023

The 'MZ generation' is accustomed to expressing their thoughts and opinions online. As a result, the role of social media in understanding the opinions and public sentiment of the MZ generation has become increasingly important. In particular, the role of social media in understanding the opinions of young people in political contexts such as policies and elections is becoming more significant. Traditionally, in such political situations, various institutions conduct opinion surveys to grasp the opinions of the people. However, existing opinion surveys have many errors and limitations in understanding the specific opinions of the entire population since they are conducted on arbitrary individuals through survey techniques. Online communities are representative social media that share the opinions of the public on specific issues such as politics, economics, and culture. Therefore, online communities are widely used as a means to supplement the limitations of traditional opinion polls. In particular, the MZ generation is familiar with online platforms, and their political support has significant influence on election results and policy decisions. With this regard, this study analyzed the relationship between the sentiment reflected in online community text data by age group on major candidates and public opinion survey support rates during the Korean presidential election for those in their 20s. The analysis showed that negative sentiments reflected in online communities by the MZ generation have a negative correlation with public opinion survey support rates. This study contributes to theory and practice by revealing a significant association between social media and public opinion polls.

• Genomics & Informatics
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• 제16권1호
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• pp.14-20
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• 2018

Despite the importance of mutation rate, some difficulties exist in estimating it. Next-generation sequencing (NGS) data yields large numbers of single-nucleotide polymorphisms, which can make it feasible to estimate substitution rates. The genetic substitution rates of Hanwoo and Holstein cattle were estimated using NGS data. Our main findings was to calculate the gene's substitution rates. Through estimation of genetic substitution rates, we found: diving region of altered substitution density exists. This region may indicate a boundary between protected and unprotected genes. The protected region is mainly associated with the gene ontology terms of regulatory genes. The genes that distinguish Hanwoo from Holstein in terms of substitution rate predominantly have gene ontology terms related to blood and circulatory system. This might imply that Hanwoo and Holstein evolved with dissimilar mutation rates and processes after domestication. The difference in meat quality between Hanwoo and Holstein could originate from differential evolution of the genes related to these blood and circulatory system ontology terms.