• 설비공학논문집
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• 제13권8호
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• pp.730-738
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• 2001

This work discusses the pressure droop, heat and mass transfer of the finned-tube heat exchangers having 7 mm tubes and offset strips in dehumidifying applications. It focuses on the fin material saving and the reduction of pressure drop. The experiment was conducted using three times scaled-up models to simulate the performance of the prototype. Eight kinds of fins having different strips and S shape edges were tested. the area density of the strip was a major factor and its shape and the location were secondary factors on the pressure drop, the heat and mass transfer. The reduced-area fin can almost equal the non-reduced fin in the aspect of heat and mass transfer. The strip fins proposed in the present work can considerably reduce both the pressure drop and the fin material for similar thermal load.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.127-130
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• 2002

In this study, development of a new LTCC material using a non-glassy system was attempted with respect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. For LTCC application, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them, CaWO$_4$ was tamed out the suitable LTCC material. CaWO$_4$ can be sintered up to 98% of full density at 1200$^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 10.15, 62880GHz, and -27.8ppm/$^{\circ}C$, respectively. In order to modify the dielectric properties and densification temperature, 0.5∼1.5 wt% LiF were added to CaWO$_4$. LiF addition reduced the sintering temperature/time down to 800$^{\circ}C$/10∼30min due to the reactive liquid phase sintering. Dielectric constant lowered from 10.15 to 9.38 and Q x fo increased up to 92000GHz with increasing LiF content.

• 대순사상논총
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• 제44집
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• pp.53-96
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• 2023

이 글은 물질종교 접근법의 사례로 '영대(靈臺)'를 살핀 것이다. 동아시아에서 영대는 주문왕이 건립한 건축물이었다. 후대로 내려오면서 영대는 수행의 목표이자 대상인 마음 영대, 존사(存思)에서 나타나는 관념적 심장으로 그 의미가 변모되었다. 이렇게 동아시아에서 영대는 물질이기도 했고, 비물질이기도 했다. 그 두 의미는 각각의 맥락에서 사용되었을 뿐, 서로 연결되었던 적은 없었다. 한국 근대에 출현한 대순진리회는 봉신(封神)이라는 개념을 사용하여 이 둘을 하나로 묶었다. 그러니까 천지신명을 모시고 제천을 했던 주문왕의 영대를 신봉어지(神封於地)의 장소로 설명하고 자신의 신전 이름으로 활용했으며, 수행의 정도에 따라 그에 맞는 신명이 수행자의 마음을 통해 응한다는 논리를 세워 인간의 마음 영대를 신봉어인(神封於人)의 장소로 규정했다. 레비-스트로스의 관점에서 보면 동아시아의 전통에서 발견되는 요소들, 즉 주문왕의 건축물 영대와 『장자』·『황정경』 등에서 보이는 마음 영대를 일관된 논리로 묶어내면서 교리 체계 안에 구축하는 이 모습은, 과거의 전통 개념들을 재창조하는 브리콜라주에 해당한다. 그렇다면 에릭 홉스봄의 표현을 빌려서, 대순진리회의 영대는 기존하는 물질 영대와 비물질 영대를 가로지르는 '발명된 영대(invented Yeongdae)'라고 말할 수 있다.

• 한국의류학회지
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• 제18권3호
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• pp.327-338
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• 1994

KES-F system is widely used in hand evaluation, however, it has encountered some challenges, such as the overlapping of primary hand value, lack of predictability in case of women's thin dress, difficulties in communication due to complexity of primary hand expression and cultural differences in subjective evaluation. Therefore, this study was intended 1) to find out the Korean primary hand expressions(factors) of the overall concept of fabric hand associated with women's spring- fall dress fabrics, 2) to develope the fabric hand attributes of those fabrics and 3) to show whether there are any differences between Korean textile experts and non-experts in terms of the concept of fabric hand descriptors of hand attributes. Data base of hand descriptors were collected by extensive interview 60 experts and 10 non - experts using 110 spring-fall dress fabrics. Finally, hand of selected fabrics was assessed by 205 experts and 265 non-experts using 7-point scale of 26 descriptors based on the data base. Subjective ratings were analyzed by common factor analysis with varimax rotation. It was found that Korean primary hand expression indicated rather simple property, hence, did not equate exactly with Japanese experssion(e.g. koshi, shinayakasa, etc.) which contains several material properties. There were differences in stretch IE resilience, especially liveliness, between the judgement of non- ex- pert than to experts. Surface- related category was more important to non-experts than to experts. Slight differences were found between both groups in terms of preferred descriptors. Important descriptors as a rating scale were suggested.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.231-232
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• 2008

The coupling between electric, magnetic, and structural order parameters results in the so-called multiferroics, which possess ferroelectricity, ferromagnetism, and/or ferroelasticity. The simultaneous ferroelectricity and ferromagnetism (magnetoelectricity) allow potential applications in information storage, spintronics, and in magnetic or electric field sensors. Perovskite compound $BiFeO_3$ (BFO) is antiferromagnetic below Neel temperature of 647K and ferroelectric with a high Curie temperature of 1043K. It exhibits weak magnetism at room temperature(RT) due to the residual moment from a canted spin structure. It is likely that non-stoichiometry and second-phase formation are the factors which cause leakage in BFO. It has been suggested that oxygen non-stoichiometry leads to valence fluctuations of Fe ions in BFO, resulting in high conductivity. To reduce the large leakage current of BFO, one attempt is fabricating donor doped BFO compounds and thin films. We report here the successful fabrication of the Nd, Ti co-doped $BiFeO_3$ ceramics and thin films by pulsed laser deposition technique.

• 지구물리
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• 제6권2호
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• pp.71-77
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• 2003

Generally the dynamic characteristics of stone wall structures depend on several factors such as contact, the type of interlocking bonding stones, and the filling materials. This paper describes a non-destructive technique for diagnosis of historic masonry stone structures using the measurement of natural frequency technique. For this purpose, the castle wall of Nag-An Folk Town located in Sunchon, Korea was selected as a model. The Nag-An Town Castle is one of the well maintained historical remains constructed in the Chosun Kingdom of Korea. The construction started in 1397 A.D and was finished in 1626 A.D. The non-mortar castle wall is 1470m long and the average height is 4m with a width of 3 4m. The exterior of the wall is bonded with 1 2 m rectangular rough-faced stone and the inside of the wall is filled with gravel. The traditional village still remains inside the Nag-An Town Castle, and they have a regional food festival every October. Transverse vibrations were measured at 8 points around the castle. The measured natural frequency of the first mode was 26Hz 41Hz, and the shear modulus of filling material was 2.142 x $10^3$ ~ 8.915 x $10^3$kgf/$cm^2$ . With these results, it may be assumed that the filling material is gravel or a sand-gravel mixture. It is expected that the information provided by this paper will be useful for addressing the maintenance problems of the old castle walls.

• Metals and materials international
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• 제24권6호
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• pp.1432-1437
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• 2018

This work investigated edge-cracking behavior of equiatomic CoCrFeMnNi high-entropy alloy during hot rolling at rolling temperatures $500{\leq}T_R{\leq}1000^{\circ}C$. Edge cracks did not form in the material rolled at $500^{\circ}C$, but widened and deepened into the inside of plate as $T_R$ increased from $500^{\circ}C$. Edge cracks were most severe in the material rolled at $1000^{\circ}C$. Mn-Cr-O type non-metallic inclusion and oxidation were identified as major factors that caused edge cracking. The inclusions near edge region acted as preferential sites for crack formation. Connection between inclusion cracks and surface cracks induced edge cracking. Rolling at $T_R{\geq}600^{\circ}C$ generated distinct inclusion cracks whereas they were not serious at $T_R=500^{\circ}C$, so noticeable edge cracks formed at $T_R{\geq}600^{\circ}C$. At $T_R=1000^{\circ}C$, significant oxidation occurred at the crack surface. This accelerated edge crack penetration by embrittling the crack tip, so severe edge cracking occurred at $T_R=1000^{\circ}C$.

• 한국수산과학회지
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• 제28권1호
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• pp.15-22
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• 1995

새로운 식중독 원인균으로 알려지고 있는 V cholerae non-O1과 V mimicus의 분포와 서식 조건을 밝히고자 금강 하구에서 1993년 3월 26일부터 1994년 2월 22일까지 수질 환경과 V cholerae non-O1 및 V mimicus의 분포를 조사한 결과는 다음과 같다. 1. V cholerae non-O1은 해수 54개 시료에서 $16.7\%$, 뻘 49개 시료에서 $6.1\%$, 전체 $11.7\%$가 검출되었으며 V mimicus는 해수 54개 시료에서 $11.1\%$, 뻘 49개 시료에서 $10.2\%$, 전체 $10.7\%$가 검출되었다. 2. V cholerae non-O1과 V. mimicus는 수온 $24^{\circ}C$이상, 염도 $10\%o$ 이하의 기수에서 주로 검출되었으나, 수온이 $3.5^{\circ}C$인 1월에 뻘에서 검출되었다. 3. V cholerae non-O1과 V. mimicus의 서식에 영향을 주는 주요 인자는 온도, 염도 및 유기물질의 오염이며, V. cholerae non-O1은 V. mimicus보다 염도 변화에 대한 적응력이 더 높았다.

• Safety and Health at Work
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• 제8권2호
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• pp.206-211
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• 2017

Background: Self-reported low back pain (LBP) has been evaluated in relation to material handling lifting tasks, but little research has focused on relating quantifiable stressors to LBP at the individual level. The National Institute for Occupational Safety and Health (NIOSH) Composite Lifting Index (CLI) has been used to quantify stressors for lifting tasks. A chemical exposure can be readily used as an exposure metric or stressor for chemical risk assessment (RA). Defining and quantifying lifting nonchemical stressors and related adverse responses is more difficult. Stressor-response models appropriate for CLI and LBP associations do not easily fit in common chemical RA modeling techniques (e.g., Benchmark Dose methods), so different approaches were tried. Methods: This work used prospective data from 138 manufacturing workers to consider the linkage of the occupational stressor of material lifting to LBP. The final model used a Bayesian random threshold approach to estimate the probability of an increase in LBP as a threshold step function. Results: Using maximal and mean CLI values, a significant increase in the probability of LBP for values above 1.5 was found. Conclusion: A risk of LBP associated with CLI values > 1.5 existed in this worker population. The relevance for other populations requires further study.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.1988-1997
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• 2005

This study is concerned with structural integrity evaluations for the interference-fit flywheels in reactor coolant pumps (RCPs) of nuclear power plants. Stresses in the flywheel due to the shrinkage loads and centrifugal loads at the RCP normal operation speed, design overspeed and joint-release speed are obtained using the finite element method (FEM), where release of the deformation-controlled stresses as a result of structural interactions during rotation is considered. Fracture mechanics evaluations for a series of cracks assumed to exist in the flywheel are conducted, considering ductile (fatigue) and non-ductile fracture, and stress intensity factors are obtained for the cracks using the finite element alternating method (FEAM). From analysis results, it is found that fatigue crack growth rates calculated are negligible for smaller cracks. Meanwhile, the material resistance to non-ductile fracture in terms of the critical stress intensity factor (K$_{IC}$) and the nil-ductility transition reference temperature (RT$_{NDT}$) are governing factors for larger cracks.