• Nuclear Engineering and Technology
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• 제49권1호
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• pp.196-208
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• 2017

This study presents an experimental work in a petrochemical company for scanning a buried pipeline using $Tc^{99m}$ radiotracer based on the measured velocity changes, in order to determine the flow reduction along a pipeline. In this work, $Tc^{99m}$ radiotracer was injected into the pipeline and monitored by sodium iodide scintillation detectors located at several positions along the pipeline. The flow velocity has been calculated between every two consecutive detectors along the pipeline. Practically, six experiments have been carried out using two different data acquisition systems, each of them being connected to four detectors. During the fifth experiment, a bypass was discovered between the scanned pipeline and another buried parallel pipeline connected after the injection point. The results indicate that the bypass had a bad effect on the volumetric flow rate in the scanned pipeline.

• 항공우주시스템공학회지
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• 제17권5호
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• pp.11-18
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• 2023

The architecture of the Fuel Thermal Management System (FTMS) in a commercial aircraft engine was built to model and simulate the fuel system. The study shows the thermal interactions between the fuel and engine lubrication oil through the mission profile of a high bypass ratio, two-spool turbofan engine. Fuel temperature was monitored as it flowed through each sub-component of the fuel system during the mission. The heat load in the fuel system strongly depended on the fuel flow rate, and was significantly increased for the periods of cruise and descent with decrease of fuel flow rate, rather than for the periods of take-off. Due to the thermal interaction in the pump housing, the fuel temperature at the outlet of the low-pressure pump was increased (4.0, 9.2, and 30.0) % over the case without thermal interaction for take-off, cruise, and descent, respectively.

• 한국식생활문화학회지
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• 제8권4호
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• pp.337-348
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• 1993

This study was carried out to investigate the succession patterns of dietary culture and to find out all the educational problems with female college students in both countries as the central figure. The results are as follows. The degree of knowledge acquisition about food of annual custom is 58% in Korea and 72% in Japan. What the rate of knowledge acquisition is high among both countries’ similar food of annual custom are ${\ulcorner}Seolnal(Gantan){\lrcorner}$, ${\ulcorner}Sambok(Doyonohi){\lrcorner}$, and ${\ulcorner}Chuseok(Tsukimi){\lrcorner}$. Cooking experience of festive food is 45% in Korea and 58% in Japan. Among both countries' common festive food what cooking experience is high in Korea are ${\ulcorner}Seolnal{\lrcorner}$ and ${\ulcorner}Chuseok{\lrcorner}$, which are over 97%. In Japan those are ${\ulcorner}Gantan{\lrcorner}$ and ${\ulcorner}Tsukimi{\lrcorner}$, which are over 80%. Regarding learning experience of festive food ${\ulcorner}Seolnal{\lrcorner}$ and ${\ulcorner}Gantan{\lrcorner}$ are beyond 80% and ${\ulcorner}Chuseok{\lrcorner}$ is 88%. In Japan ${\ulcorner}Tsukimi{\lrcorner}$ is 71% and ${\ulcorner}Omisoka{\lrcorner}$ is 85%. The learning sources of food of annual custom are parents and schools in common, and Korea has another learning sources, mass communication. Festive food that is cooked shows much similarity between two countries, but each country has originality. As common food of annual custom ${\ulcorner}Seolnal{\lrcorner}$ has nine kinds of food, ${\ulcorner}Sambok{\lrcorner}$ has three kinds, and ${\ulcorner}Chuseok{\lrcorner}$ has five kinds in Korea In Japan ${\ulcorner}Gantan{\lrcorner}$ has fourteen kinds of food, ${\ulcorner}Doyonohi{\lrcorner}$ has three kinds, and ${\ulcorner}Tsukimi{\lrcorner}$ has five kinds. The successive consciousness about food of annual custom is concentrated on a specific food in Korea. And Japanese consciousness is shown as an expansion-type on diverse food. Korean successive consciousness is 69.4% and Japanese consciousness is 82%. The higher the rate of knowledge acquisition, cooking experience, and learning experience are in both countries, the higher successive consciousness is. So we must note for the importance of home and school’s education.

• 소성∙가공
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• 제28권6호
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• pp.368-374
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• 2019

The past recent years have seen an increasing use of high-strength steel sheets in the automotive industry. However, the formability and damage prediction of these materials requires accurate acquisition of necking and fracture strains. Digital image correlation (DIC) is used to accurately capture the necking and fracture strains during testing. The fact that single time points of capturing vary with frame rate makes the need for an investigation necessary. For the high-strength steel DP980, the frame-rate dependences of the final necking and fracture strains values are analyzed here. To eliminate the influence of gauge length, the strains were measured locally by DIC. Results for three specimen shapes obtained with frame rates of 1 and 900 fps (frames per second) were considered and based on them, triaxiality failure diagrams (TFD) are established. It was observed that after diffuse necking, the deformation path departed from the initially linear one, and the stress triaxiality grew with ongoing deformation. It was further revealed that the frame rate-dependence of the necking strain was rather low (< 2%), whereas the fracture strain could be underestimated by up to 8% when the lower frame rate of 1 fps was used (compared with 900 fps). In this study, this issue is investigated while taking into consideration the three different triaxialities. These results demonstrate the importance of choosing an appropriate frame rate for the determination of necking and fracture strains in particular.

• 한국도서관정보학회지
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• 제54권4호
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• pp.281-306
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• 2023

본 연구는 최근 3년(2020-2022)간 국내 전자출판물의 납본·자체수집·수증 현황과 ISBN이 발급된 전자출판물의 납본 및 미납본 현황을 분석하였다. 이를 통해 국내 전자출판물의 납본 의무 이행 독려하기 위한 개선방안을 제안하고자 하였다. 먼저 국내 전자출판물의 납본·자체수집·수증 현황의 주요 분석결과는 다음과 같다. 전자출판물 수집형태는 자체수집(57.07%), 납본(41.74%), 수증(1.19%)이었으며, 파일 형식은 전자책(pdf, epub), 웹툰(jpg), 오디오북(mp3)으로 다양하였다. 주로 2012년부터 2022년 사이에 출판된 전자출판물이 수집되었으며, 1960년부터 2011년 사이에 출판된 자료도 일부 수집되었다. 자체수집은 웹툰이 많았고, 납본은 전자책이 주를 이루었다. ISBN 발급 현황을 보면, 자료유형은 전자책(96.2%)이, 주제분야는 문학 분야가 가장 많은 ISBN을 발급받았다. 2020년부터 2022년 사이에 가장 많은 ISBN이 발급되었다. ISBN 발급 상위 10위 발행처의 납본율을 보면, 전체적으로 ISBN 발급을 받은 발행처들의 납본율이 저조하여 이를 개선하기 위한 노력이 필요한 것으로 나타났다. 이에 개선방안으로 발행처의 납본 의무에 대한 인식 제고, 인센티브 제공 및 제재 조치 강화, 납본 현황의 투명한 공개를 통한 자발적 참여 유도, 그리고 ISBN 발급 및 납본 시스템의 데이터 정확성 향상을 위한 기술적 조치의 필요성을 제안하였다.

• 벤처창업연구
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• 제17권4호
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• pp.219-232
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• 2022

창업의도에 관한 실증연구는 지난 수년간 다양한 관점에서 진행되어왔다. 최근에는 COVID-19 팬데믹의 여파로 전 세계적으로 경기가 침체되면서 실업률이 증가하고 있으며 창업이 고용 창출의 대안으로 떠오르고 있다. 창업의도에 긍정적인 영향을 주는 수많은 선행 변수들이 있지만, 본 연구에서는 창업자 개인의 특성이라 볼 수 있는 창업 자기효능감과 환경적 특성인 창업자 가족배경에 초첨을 맞추어 이 변수들이 창업의도에 미치는 영향에 대하여 고찰하였다. 본 연구는 스크리닝 질문을 통하여 창업교육을 받은 경험이 있는 사람을 대상으로 Prolific에서 300명의 글로벌 응답자에 대한 온라인 조사로 진행되었다. 창업자기효능감의 매개효과에 대한 연구는 국내 연구에서 다수 확인된 바가 있으므로 본 연구에서는 글로벌 샘플을 대상으로 하여 연구의 일반화를 도모하고자 한다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 창업지식습득은 창업의도에 긍정적인 영향을 미쳤다. 둘째, 창업자기효능감은 창업지식습득과 창업의도의 관계를 매개하였다. 셋째, 창업자 가족배경은 이 관계를 조절하였다. 구체적으로 살펴보면, 창업지식습득 수준이 낮을 때에는 창업자 가족배경의 낮고 높음에 상관없이 창업의도가 낮은 반면, 창업지식습득수준이 높을 때에는 창업자 가족배경이 낮을 때에 비하여 창업자 가족배경이 높은 경우에 창업의도가 증가하였다. 본 연구의 시사점은 다음과 같다. 첫째, 창업 준비 과정에서 창업교육이 창업의도를 향상하는데 필요한 조건이며, 성공적인 창업을 위해서는 지속적인 창업교육이 이루어져야 한다. 둘째, 창업지식습득 수준을 높일수록 창업자기효능감이 높아지고 궁극적으로 창업의도 또한 고양시킬 수 있다. 셋째, 가족 중에 창업 경험이 있는 경우 창업 심화 과정을 이수하도록 하여 창업자기효능감을 증진시켜 창업을 더욱 촉진할 수 있다. 결론적으로 대학생들의 창업 활성화를 위해서는 창업 활동, 창업 교육 등 창업 관련 프로그램 활성화가 중요하다. 따라서 교육기관은 학생들이 창업지식습득을 할 수 있는 기회를 더 많이 제공함으로써 창업자기효능감을 향상시키고, 이를 통하여 창업의도를 높일 수 있도록 다양한 수준의 창업프로그램을 개발하고 제공해야 한다. 또한 가족 중에 창업 경험이 있는 사람들을 위한 창업지원 정책이나 심화 교육 과정을 개발할 필요가 있다.

• 한국치위생학회지
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• 제8권3호
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• pp.161-175
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• 2008

With the change of medical environment, people are taking interest not just in treatment but in the prevention of oral diseases. As people's interest in oral diseases increases, the number of dental institutions is increasing continuously and this is heightening the necessity and importance of professional dental hygienists equipped with expert knowledge of oral health. Thus the present study purposed to survey and analyze the current state and weight of works carried out by dental hygienists, and to propose dental hygienists' works desirable in the medical environment changing its focus from treatment to prevention. The results of this study are as follows; 1. In the results of dividing dental hygienists' works into oral examination and preliminary examination, preventive works, assistance to dental treatment, oral health education, hospital administration and management, and surveying the performance rate of these works, the work of the highest performance rate in preliminary examination was collection of patients' systemic history (87.6%). It was also scaling (96.9%) in preventive dental treatment, preparation for treatment (96.5%) in assistance to dental treatment, education on the toothbrushing method (92.3%) in oral health education, and tool disinfection and management (72.2%) in hospital administration and management. 2. When the performance rate was surveyed according to age, institution, and work experience, the performance rate by work area was highest in dental hygienists aged between 27~28, those working at a dental clinic, and those with 4~6 years' work experience. 3. The weight of dental hygienists' works was high in order of assistance to dental treatment (59.1%), observation of oral health condition and preliminary examination (12.4%), oral health education (12.4%), hospital administration and management (10.4%), and preventive dental treatment (5.8%), but in the results of surveying perception on the importance of works, the importance was high in order of oral health education (34.7%), preventive dental treatment (29.0%), observation of oral health condition and preliminary examination (19.3%), assistance to dental treatment (11.2%), and hospital administration and management (5.8%), showing that the weight of works carried out current was different from perception on the weight of works regarded as important. 4. To the question on parts to be developed in response to the change of medical environment, the most frequent answers were the establishment of their roles as preventive dental practitioners (75.7%), and the establishment of their roles as oral health educators (74.9%). This was consistent with the works that dental hygienists gave the highest weight to, and suggested that dental hygienists regarded preventive dental treatment as most important. Development of abilities to give counsel to patients was 55.2%, acquisition of theoretical knowledge of dental treatment 42.1%, improvement in quality as a hospital manager 28.2%, and acquisition of skills to assist dental treatment 23.2%. These show that, even with regard to the development of future oriented dental hygienists' capacities, assistance to dental treatment was perceived less important as it was with regard to the importance of work.

• 핵의학기술
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• 제16권2호
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• pp.18-24
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• 2012

Lung SPECT는 planar scan 보다 깊이 위치한 병변을 명확히 보여주며 보다 예민한 것으로 보고되고 있다. 그러나 ventilation SPECT는 정맥주사를 통해 방사성의약품을 주입하는 perfusion SPECT와 다르게 환자의 호흡을 통해 흡입시키므로, 원활한 호흡이 불가능한 환자의 경우 목적 장기에 방사성의약품의 섭취율이 저하되고 검사에 유효한 적정count/rate가 낮아지므로 필연적으로 검사시간이 길어지게 되어 이에 수반되는 여러 문제로 인하여 실제 임상에 적용하기 어려운 실정이다. 따라서 본 연구는 고감도(high sensitivity) 특성을 지닌 AP (All Purpose) 혹은 GP (General Purpose) collimator를 사용하여 low count/rate 환자의 검사시간을 단축시킴으로써 lung ventilation SPECT 임상적용 가능성과 유용성을 평가하였다. 정상 성인 남녀 4명($24.3{\pm}0.95$세)을 실험대상으로 Technegas 370 MBq을 흡입시키고, E.cam SPECT를 사용하여 count/rate를 측정한 후, LEUHR, LEHR, LEAP collimator를 장착하여 300counts acquisition 조건으로 ANT, POST, LPO, RPO, both-LAT 총 6 view의 lung ventilation planar scan 하였다. 동일 실험 대상자를 본원에서 사용하던 기존 프로토콜을 적용하여 70 kcounts/view acquisition 조건으로 high counting mode SPECT를 시행하고, 같은 방법으로 7kcounts/view acquisition하여 비교 실험인 low counting mode SPECT를 시행한 후 모든 실험의 결과를 lung segmentation ratio와 검사 소요시간을 통해 비교하여 분석하였다. 각 실험군 사이의 상관관계를 분석하기 위해 paired t-test를 시행하였고, p값이 0.05를 초과할 때 실험의 통계적 의미가 있는 것으로 판단하였다. 모든 자료의 통계처리는 SPSS ver. 20을 사용하였으며, 각 실험 결과는 산술 및 기하 평균(mean)을 구하고${\pm}$표준편차(SD)를 산출하였다. 실험 결과 lung planar scan은 300 kcounts/6 iew를 acquisition하여 총 1,800 kcounts를 획득하였다. 반면 7 kcounts/view로 acquisition한 low counting mode SPECT의 경우 collimator 종류에 따라서 최소 773 kcounts에서 최대 1,106 kcounts를 획득하였고, 70 kcounts/view로 acquisition한 high counting mode SPECT의 경우 collimator 종류에 따라서 최소 7,984 kcounts에서 최대 10,222kcounts를 획득하였다. 모든 실험 자료를 통해 실험대상 4명의 lung segmentation ratio를 산출하고, 평균값과 표준편차를 계산한 결과, LT:RT lung ratio는 순서대로 각각 45.5:54.5 (${\pm}0.26$), 45.4:54.6 (${\pm}0.40$), 50.1:49.9 (${\pm}0.28$), 49.4:50.6 (${\pm}0.57$)이었다. 따라서 정량분석한 결과 planar scan과 low, high counting mode SPECT사이 collimator 종류에 의한 lung segmentation ratio는 오차 범위내에 모두 존재하였다. 보다 자세한 분석을 위해 기존의 LEHR collimator를 장착한 planar scan과 비교 실험인 LEAP collimator를 장착한 low counts mode SPECT를 통계처리한 결과 p-value가 0.10이상으로 두 실험의 결과는 통계적으로 유의하였다. 실험에 소요된 시간을 분석한 결과 planar scan은 LEUHR, LEHR, LEAP collimator 순서로 각각 $1803{\pm}268$ sec, $915{\pm}162$ sec, $501{\pm}134$ sec이었고, 비교실험인 low counting mode SPECT는 $1125.5{\pm}103.6$ sec, $900{\pm}64$ sec, $740{\pm}0$ sec 이었으며, 본원에서 사용하던 기존 프로토콜인 high counting mode SPECT는 $5794.5{\pm}946.5$ sec, $3620{\pm}397.9$ sec, $2020{\pm}104.5$ sec이었다. 관심실험인 LEAP collimator를 장착한low counting mode SPECT의 검사 소요시간 740 sec에 비하여, 기존 본원의 프로토콜인 LEHR collimator를 장착한 high counting mode SPECT의 검사 소요시간 평균은 3620sec이므로, 약 5배 정도 시간 단축이 가능한 것으로 조사되었으며, 모든 실험의 정량분석 결과도 임상적으로 유의한 것으로 분석되었다. 결국 high sensitivity LEAP collimator를 장착하여 lung SPECT를 시행하면, 임상적으로 유의한 정량분석 결과를 얻을 수 있으며, 동시에 검사시간을 효과적으로 단축시킬 수 있음을 의미한다.

• 한국가시화정보학회지
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• 제9권4호
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• pp.47-53
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• 2011

A water driven ejector loop was designed and constructed for air absorption. The used ejector was horizontally installed in the loop and annular water jet at the throat entrained air through the circular pipe placed at the center of the ejector. Wide range of water flow rate was provided using two kinds of pumps in the loop. The tested range of water flow rate was 100${\ell}$ /min to 1,000 ${\ell}$/min. Two-phase flow inside the ejector loop was simulated by CFD analysis. Homogeneous particle model was used for void fraction prediction. Water and air flow rates and pressure drop through the ejector were automatically recorded by using the LabView based data acquisition system. Flow characteristics and air bubble velocity field downstream of the ejector were investigated by two-phase flow visualization and PIV measurement based on bubble shadow images. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1002-1009
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• 2004

Direct contact air conditioning systems, in which heat and mass are transferred directly between air and water droplets, have many advantages over conventional indirect contact systems. The purpose of this research is to investigate the cooling and heating performances of direct contact air conditioning system for various inlet parameters such as air velocity, air temperature, water flow rate and water temperature. The experimental apparatus comprises a wind tunnel, water spray system, scrubber, demister, heater, refrigerator, flow and temperature controller, and data acquisition system. The inlet and outlet conditions of air and water are measured when the air contacts directly with water droplets as a counter flow in the spray section of the wind tunnel, and the heat and mass transfer rates between air and water are calculated. The droplet size of the water sprays is also measured using a Malvern Particle Analyzer. In the cooling conditions, the outlet air temperature and humidity ratio decrease as the water flow rate increases and as the water temperature, air velocity and temperature decrease. On the contrary, the outlet air temperature and humidity ratio increase in the heating conditions as the water flow rate and temperature increase and as the air velocity decreases.