• Journal of Welding and Joining
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• v.17 no.2
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• pp.25-28
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• 1999

국내에 건설되어 거의 20∼30년 가동되고 있는 발전설비, 석유화학 플랜트 등 거대설비 기기의 건전성(integrity) 및 신뢰성 확보와 잔존수명 예측을 위해서는 구조물 내부 또는 표층부에 존재하는 결 함의 특성을 아는 것과 함께 그 재료의 특정 부위에 어느정도의 응력이나 변형이 있는가를 아는 것이 매우 중요하다. 일반적으로 강 용접부의 비파괴적 결함검출에는 주로 SV파(vertically shear wave)와 SH파(horizontally shear wave)라 불리는 횡파를 이용한 초음파사각탐상법이 실용화되어 이용되고 있다. 그러나 비파괴적인 방법에 의한 실험적인 잔류응력 측정, 변형해석법에는 전기 저항 및 자기 스트레인 게이지법, X선회절법, 광탄성법(photoelasticity), 모아레(Mohr's)법, 레이저스펙클(Laser speackle)법, 응 력도료법, Barkhausen Nosise법, Caustics법 등이 제시되어 있으나 그 유용성 면에서는 아직 해결되야할 문제가 많이 남아 있는 실정이다. 응력이나 변형을 해석하는 방법으로 이론적 방법, 계산적 방법 실험적 방법이 잇다. 이론적 방법에는 재료 역학적으로 취급하는 방법, 탄성론 등이 있고, 계산적인 방법에는 유한요소법이 있지만, 이론적 방법이나 계산적 방법만으로는 해석이 불가능한 경우가 많기 때문에 실험 적 방법이 필요하게 된다. 이 글에서는 파괴 시험 또는 다른 비파괴평가기술에 비해 간편한 측정, 높은 측정정도, 시험결과 도출의 신속성, 검사비용의 절감 등 많은 장점을 가지고 있고 실험적으로 유용성이 일부 검증되고 있는 음탄성법(Acoustoelasticity)에 의한 잔류응력 측정법에 관해 소개하고자 한다.TEX> mg/L(평균 49 mg/L)로 비교적 안정적인 처리효율을 보여주었다. 본 연구결과 HVC 공정은 화학약품 사용량의 절감 및 이에 따른 화학슬러지 발생량의 감소를 기대 할 수 있는 친환경기술로 유지관리비를 최소화할 수 있는 장점이 있었다. 않은 사람들 중 미래의 검진실행의지에 건강소식지가 영향을 미친 경우는 48.7%였다. 보건교육을 받은 후 유방암 자가검진 실천율은 사업군에서 53.9%로 받기 전의 27.3%보다 증가하였으나 대조군의 경우는 별 차이가 없었다. 연령별로는 60대가 가장 높았고 사업군에서 검진율의 증가분은 30대가 가장 컸다. 교육수준별로는 사업군은 고졸이, 대조군은 전문대졸이 가장 높았고 사업군에서 검진율의 증가분은 고졸에서 가장 컸다. 보건교육 후 유방암과 관련된 건강지식의 정도는 사업군이 3.7점으로 대조군보다 유의하게 높았으며, 유방암 자가검진법을 실천하는 사람들의 동기는 ‘일반 대중매체의 영향’이 가장 많았으며 건강소식지가 동기인 경우도 20.4%였다. 사업군에서 건강소식지가 유방암 자가검진법 실천에 영향을 미친 경우가 79.6%였으며 유방암 자가검진법에 관한 보건교육을 받고 실천하지 않은 사람들 중 미래의 실천의지에 건강소식지가 영향을 미친 경우는 43.6%였다. 이상의 소견에서 지역주민을 대상으로 인쇄매체를 통한 보건교육은 인쇄물만으로도 쉽게 실천 할 수 있는 유방암 자가검진법이 가장 효과적이었으며, 자궁암검진에 관해서도 검진을 받을 수 있도록 지역사회의 보건의료의 하부구조를 정비하여 제도적 장치를 마련하고 정보를 제공한다면 자궁암검진 실천율도 증가할 것이다.고 12.9% 의 발달율을 보여 유의적인 차이를 보이지 않았다. 이상의 결과로 보아 핵이식 수정란을 효율적으로 생산하기 위하여

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.155-164
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• 2014

Carbon-fiber-reinforced plastic (CFRP) composites are increasingly being used in a variety of industry applications, such as aircraft, automobiles, and ships because of their high specific stiffness and high specific strength. Aircraft are exposed to high temperatures and high humidity for a long duration during flights. CFRP materials of the aircraft can absorb water, which could decrease the adhesion strength of these materials and cause their volumes to change with variation in internal stress. Therefore, it is necessary to estimate the characteristics of CFRP composites under actual conditions from the viewpoint of aircraft safety. In this study air-coupled ultrasonic testing (ACUT) was applied to the evaluation of water absorption properties of CFRP composites. CFRP specimens were fabricated and immersed in distilled water at $75^{\circ}C$ for 30, 60, and 120 days, after which their ultrasonic images were obtained by ACUT. The water absorption properties were determined by quantitatively analyzing the changes in ultrasonic signals. Further, shear strength was applied to the specimens to verify the changes in their mechanical properties for water absorption.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.717-724
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• 2001

This study was conducted in an attempt to quantify some traits that may be involved in the reproductive process of Pinus thunbergii. During the past 6 years (1995-2000), we surveyed flowering patterns of 60 P. thunbergii clones in a seed orchard which was established in Anmyon-do, 1979. From this survey, we estimated clonal contributions of male and female flowers and sexual asymmetry. Among 60 clones, 18 clones (30%) accounted for 0.37 (1999)~0.46 (1995) of clonal contribution in female flowers and 0.44 (1999)~0.57 (1995) of clonal contribution in male flowers. As compared with the previous reports in other pine species, more clones made contributions to reproductive process in P. thunbergii seed orchard. The relative effective population numbers for females (v♀) varied from 0.59 (1995) to 0.91 (1999) and those for males ( v♂) were between 0.56 (1995) and 0.83 (1998) at gamete level. This showed that the female gametes effectively contribute to the reproductive process more than did the male gametes. The relative effective population numbers at clonal level ($v_b$) were in the range of 0.72 (1995) and 0.93 (1999). More than 73% of the total clones showed values of 0.4~0.6 ($0.5{\pm}0.1$) in maleness index. The values averaged over all the clones were temporally variable with the range of 73% in 1996 and 100% in 2000. The degree of sexual asymmetry ($A_s$) ranged from 0.09 to 0.26. These values were relatively low when compared with those of other trees, suggesting that P. thunbergii seed orchard remains a high level of homogeneity in the number of male and female. All of the various types of effective population numbers were positively correlated with each other while they were negatively correlated with the degree of sexual asymmetry.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.383-389
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• 2021

Obesity is associated with impaired intestinal epithelial barrier function, which contribute to host systemic inflammation and metabolic dysfunction. Korean traditional foods, fiber-rich bean products, have been various biological activities in anti-inflammatory responses, but has not reported the large intestinal health. In this study, we investigated the intestinal health promoting effect of cooked soybeans (CSB) on high fat diet (HFD)-induced obesity model. SD rat were fed either a HFD or HFD supplemented with 10.6% CSB (HFD+CSB) for animal experimental period. CSB treatment significantly decreased the HFD-induced weights of body and fat. Also, CSB treatment improved HFD-reduced tight junction components (ZO-1, Claudin-1, and Occludin-1) mRNA expression in large intestine tissue. Additionally, histopathological evaluation showed that CSB treatment attenuated the HFD-increased inflammatory cells infiltration and epithelial damages in large intestine tissue. At the genus level, effects of CSB supplement not yet clear, while dietary effects showed differential abundance of several genera including Lactobacillus, Duncaniella, and Alloprevotella. NMDS analysis showed significant microbial shifts by HFD, while CSB did not shift gut microbiota. CSB increased the abundance of the genera Anaerotignum, Enterococcus, Clostridium sensu stricto, and Escherichia/Shigella by linear discriminant analysis effect size analysis, while reduced the abundance of Longicatena and Ligilactobacillus. These findings indicate that CSB supplement improves HFD-deteriorated large intestinal health by the amelioration of tight junction component, while CSB did not shift gut microbiotas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.252-262
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• 2019

Following the earthquake in Gyeongju (2016) and Pohang (2017), South Korea is no longer a safe place for earthquakes. Accordingly, the need for shelters suitable for disaster environments is increasing. In this study, a lightweight composite panel was used to produce post-disaster housing for refugees to compensate for the disadvantages of existing evacuation facilities. For this purpose, an evaluation of structural performance and thermal environment for post-disaster housing for refugees composed of lightweight composite panels was performed. To assess the structural performance, a lateral loading test was conducted on a system made of lightweight composite panels. The specimens consisted of two types, which differed according to the bonding method, as a variable. In addition, the seismic and wind loads were calculated in accordance with KBC 2016 and compared with the experimental results. Regarding the energy performance, optimization of south-facing window planning and window-wall ratio and solar heat gain coefficient were analyzed to minimize heating, cooling, and lighting energy. As a result, the specimens composed of lightweight composite panels will perform sufficiently safely for lateral loads and the optimized window planning will lead to a low-energy operation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.29-38
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• 2022

Recently, seismic design for anchors is required, which are used for connecting structural members and non-structural and structural members. In this study, pull-out tests on the new expansion anchors which have been developed for cracked concrete. The anchors of 12 mm and 20 mm diameters were tested which are commonly used. Experiments were conducted on non-cracked concrete and cracked concrete to evaluate the seismic performance of the post-installed anchor. The experimental method complies with the specified test protocol (KCI, 2018). Three experimental variables are included in this study: presence of cracks, concrete compressive strength, and effective embedment depth. The strength of the anchors was evaluated with the characteristic capacity K_5% determined from the test results incorporated with the safety of 5% fractile. The characteristic capacity K_5% of the non-cracked and cracked concrete specified in KDS 14 20 54 are 9.8 and 7.0, respectively. Test results show that all groups except the three groups have higher characteristic capacity K_5% than the KDS code and the nominal strengths of the tested anchors can be determined with the obtained characteristic capacity K_5%.

• Journal of Korea Entertainment Industry Association
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• v.15 no.6
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• pp.1-13
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• 2021

This study explored the mechanism by which Trot gained a superior position in the broadcasting contents market after the TV Chosun audition program was broadcast. We analyzed the narrative structure of the program to determine what differentiation and popularization strategy the trot audition program took from the existing audition program, and analyzed in-depth interviews with music experts and interviews with the production team. appealed to viewers with a strategy that reversed the success strategy of existing audition programs. First, the strong/non-competent participants did not compete with each other, but rather the strong/skilled players competed against each other. This trot audition set the singing ability as a new 'discourse on sincerity'. Second, we broke away from the 'demon editing', which was considered essential for audition programs, took a strategy of excluding villains. Third, we broke the practice of audition programs that were supposed to show expertise in specific genres, such as idol music, hip-hop, and bands, and combined trot with various genres. Fourth, unlike previous audition programs that mainly targeted specific generations or genders, the strategy was to expand the audience by targeting various age groups. Fifth, it has formed a middle-aged fandom with a 'subtitle strategy' that uses subtitles well to arouse viewers' interest and help empathize.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.106-112
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• 2021

Catalyst poisoning by ionomers in membrane electrode assemblies of alkaline membrane fuel cells has been reported recently. We tried to improve the membrane electrode assembly's performance by controlling the solvent's ratio during electrode manufacturing. 4 Different mixing ratios of N-Methyl-2-pyrrolidone (NMP) and ethylene glycol (EG) gave four different cathode electrodes with platinum and Fuma-Tech ionomers. The electrode with higher EG improved polarization performance by about 36% compared to the NMP-based commercial ionomer. The dependence of the ionomer's dispersibility on the solvent seems responsible for the difference, which means that the non-uniform distribution of ionomers improves the performance of the electrode. High-frequency resistance, internal resistance corrected polarization curve, Tafel slope, mass activity, and impedance spectroscopy characterized the electrode. We can find that the existence of poor solvent improves cathode electrode performance. It seems to be the result of reduced poisoning of the catalyst according to the particle size distribution of the ionomer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3C
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• pp.149-158
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• 2010

In this study, the behavior of Pile-Bent structure with varying diameters subjected to lateral loads were evaluated by a load transfer approach. An analytical method based on the beam-column model and nonlinear load transfer curve method was proposed to consider material non-linearity (elastic, yielding) and P-${\Delta}$ effect. For an effective analysis of behavior Pile-Bent structure, the bending moment and fracture lateral load of material were evaluated. And special attention was given to lateral behavior of Pile-Bent structures depending on reinforcing effect of materials and ground conditions. Based on the parametric study, it is shown that the maximum bending moment is located within a depth (plastic hinge) approximately 1~3D (D: pile diameter) below ground surface when material non-linearity and P-${\Delta}$ effect are considered. And distribution of the lateral deflections and bending moments on a pile are highly influenced by the effect of yielding. It is also found that this method considering material yielding behavior and P-${\Delta}$ effect can be effectively used to perform the preliminary design of Pile-bent structures.

• Journal of Food Hygiene and Safety
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• v.8 no.3
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• pp.135-140
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• 1993

Dried fishes such as dried pollack, dried sliced squid, dried white bait, dried anchoy) and dried cod used to cook Korean traditional foods were airpacked in polyethylene tube and irradiated with 7 kGy of gamma-ray source. The effect of gamma irradiation on microbial growth in dried fishes was investigated during storage at ambient temperature for 12 months. The total aerobic bacteria in the control group were contaminated by $3.9{\times}10^{3}\;cells/g$ in dried pollack, $5.6{\times}10^{5}\;cells/g$ in dried sliced squid, $1.2{\times}10^{5}\;cells/g$ in dried white bait, $1.2{\times}10^{4}\;cells/g$ in dried anchovy and $1.2{\times}10^{4}\;cells/g$ in dried cod and 7 kGy irradiation could eliminate the bacteria and also reduce aerobic bacterial load to 1~3 log cycle and no apparent growth of microorganisms occurred during storage. Molds in the control group were contaminated by $4.0{\times}10^{2}\;cells/g$ in dried pollack, $$1.3{\times}10^{2}\;cells/g$ in dried sliced squid, $2.5{\times}10^{2}\;cells/g$ in dried white bait, 90 cells/g in dried anchovy and $2.0{\times}10^{2}\;cells/g$ in dried cod, respectively. 7 kGy irradiation could sterilize the molds and the growth of molds of nonirradiated samples were slightly decreased during storage. Yeasts in the control group were contaminated by $1.4{\times}10^{3}\;cells/g$ in dried poUack, 75 cells/g in dried sliced squid, $1.1{\times}10^{3}\;cells/g$ in dried white bait, 50 cells/g in dried anchovy, $1.6{\times}10^{2}\;cells/g$ in dried cod, respectively and irradiation could sterilize the yeasts and growth of yeasts was slightly decreased in dried pollack and dried white bait but increased in order of dried anchovy, dried cod and dried sliced squid. Coliforms in all sample were sterilized by irradiation and its growth was decreased during storage except dried anchovy.