• 농촌의학ㆍ지역보건
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• 제39권4호
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• pp.256-263
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• 2014

이 연구의 목적은 농촌지역 여중생의 골밀도와 신체활동량을 비교하는 것이다. 연구 대상자는 경상북도 달성군 D 중학교 여중생 65명이었으며, 이들을 일일 도보수에 따라 하루에 4,800 미만은 저활동군(Low PA), 4,800 - 6,300 미만은 중간활동군 (Moderate PA) 그리고 6,300 이상은 고활동군 (High PA)으로 분류하였다. 그룹 간 요추, 대퇴부, 전완에서의 골밀도는 유의한 차이가 없었다. 하지만, 높은 신체활동 집단에서는 우세손과 비우세손의 전완 골밀도 차이가 없었으나, 중간 및 낮은 신체활동 집단에서는 우세손과 비우세손의 전완 골밀도에서 유의한 차이가 나타났다. 신체활동이 적은 여자 청소년들이 우세손과 비우세손의 골밀도 차이가 나타난다는 것은 보고된 적이 없다. 비록 해부학적으로 전완의 경우 중력부하를 받는 뼈가 아닐지라도, 높은 신체활동은 비우세손의 골밀도까지 강화시킬 수 있다는 것을 보여주었다. 따라서 향후 비교적 큰 표본과 장기간 연구를 통해 낮은 강도의 신체활동 효과에 대해 더 연구할 필요가 있다고 사료된다.

• 원예과학기술지
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• 제32권5호
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• pp.607-613
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• 2014

Calcium has been associated with improved cold tolerance in many crops. The aim of this study was to investigate the changes in leaf cell $Ca^{2+}$ distribution and cell organelle ultrastructure of loquat (Eriobotrya japonica Lindl.) plants in response to cold stress at $-3^{\circ}C$, using transmission electron microscopy (TEM). Two loquat accessions, Zaozhong 6 (a commercial cultivar) and oakleaf loquat (a wild relative) were used. Cold tolerance, as measured by leaf browning rate, was higher in oakleaf plants, and calcium treatment improved cold tolerance in both species. Cold stress first induced inward transport of $Ca^{2+}$ from the intracellular space. Then, the imported $Ca^{2+}$ was aggregated around the chloroplast membrane, finally entering the chloroplast. This pattern of $Ca^{2+}$ distribution in leaf cells occurred earlier in Zaozhong 6 than in the wild loquat. With increasing time of cold exposure, the chloroplast membranes of Zaozhong 6 leaves were damaged, blurred and even disappeared, while those of wild oakleaf loquat leaves maintained their structure longer. In Zaozhong 6, cold stress induced a clear cavity between poorly structured granal thylakoids and vesicles appearing inside the chloroplast, while in oakleaf leaves cold stress had little effect on the ultrastructure of chloroplasts (although chloroplast membranes looked blurred). Loquat leaves accumulated free calcium ions around chloroplasts in response to cold stress, with earlier calcium accumulation occurring in the cold-sensitive cultivar Zaozhong 6 than in wild oakleaf loquat. These results demonstrate that these two loquat species have differences in both cold tolerance and calcium accumulation dynamics.

• 한국의류학회지
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• 제23권6호
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• pp.853-863
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• 1999

the change of physical properties (thickness, weight, air permeability) and mechanical properties(abrasion resistance breaking load and displacement) of samples were determined after heat exposure by a RPP tester. The effect of exposure time and heat flux intensity on the changes and the relationship between physical properties and mechanical properties were investigated. FR treated cotton Kevlar/PBI and Nomex with different structureal characteristics were chosen for specimens. The changes of physical properties and mechanical properties were calculated based on their initial values before heat exposure. The longer exposure time and the high heat flux intensity the more changes of those properties. Heat flux intensity was more effective on the changes, The showed to be affected by an interplay of shrinkage and pyrolysis products loss. The changes of thickness and abrasion resistance showed to be higher for plain weave fabric and those of air permeabiliyt and breaking load and displacement for twill weave fabric. While FR treated cotton which have high RPP value experienced serious and detrimental changes after heat exposure Kevlar/PBI which has low RPP value showed no high changes. In conclusion it could be confirmed that when total performance of a protective clothing is estimated retention capability of physical and mechanical properties after heat exposure as well as RPP value must be considered.

• 한국해양공학회지
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• 제23권6호
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• pp.99-104
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• 2009

PTFE has good mechanical and chemical stability at a wide range of temperatures and demonstrates a low friction coefficient value. PTFE is being used for self-lubricating parts in industry. But it shows a high wear rate. Thus, PTFE and nano-diamond powder were mixed into a composite and the wear properties of a PTFE coating layer on Al6061 was investigated. A ball-on-disk type of wear tester was used under a dry condition and different temperatures of oil. After the wear test, the wear track wasexamined by optical microscope. The PTFE-diamond showed the lowest friction coefficient (0.02) of all the lubricants in the experiments. The friction coefficient was shown to be directly related to the diamond powder in the PTFE coating. Adhesion estimations were performed by a scratch test, which is mainly used for coatings. The critical load between the coating and substrate was defined through analyses of the friction load, normal load curve, and acoustic emissions, along with optical microscope observations. The scratch test results showed that an import item (SWISS) gave the highest critical load values.

• 전기학회논문지
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• 제57권12호
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• pp.2300-2307
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• 2008

This study receives the noise transmitted in a constant audio frequency range through a microphone array in which the noise(like grease in a pan) occurs on the power supply line due to the troublesome partial discharge(arc). Then by going through a series of signal processing of removing noise, this study measures the distance and direction up to the noise caused by the troublesome partial discharge(arc) and monitors the result by displaying in the analog and digital method. After these, it determines the state of each size and judges the distance and direction of problematic part. When the signal sound transmitted by the signal source of bad insulator is received on each microphone, the signal comes only in the frequency range of 20 kHz by passing through the circuit of amplification and 6th low pass filter. Then, this signal is entered in a digital value of digital signal processing(TMS320F2812) through the 16-bit A/D conversion. By doing so, the sound distance, direction and coordinate of bad insulator can be detected by realizing the correlation method of detecting the arriving time difference occurring on each microphone and the algorithm of detecting maximum time difference.

• 운동영양학회지
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• 제25권2호
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• pp.33-37
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• 2021

[Purpose] Sex hormones deficiency leads to dramatically bone loss in particular postmenopausal women. Royal jelly has anti-osteoporosis effect due to maintain bone volume in that condition. We hypothesized that royal jelly protein (RJP, a latent residue after extracting royal jelly) also prevents bone deficient in ovariectomized (OVX) female rats, the animal model of postmenopausal women. [Methods] Female Sprague-Dawley rats (n = 30, 6 weeks age old) were sham operated (Sham; sham operated group, n = 7), OVX control group (OC, n = 7), OVX with low RJP intake group (ORL, n = 8), and OVX with high RJP intake group (ORH, n = 8) during 8 weeks experimental periods. In the end point of this experiment, the bone samples (lumbar spine, tibia, and femur) were surgically removed under anesthesia. These bone samples were evaluated bone mineral density (BMD) and bone strength. [Results] BMD of lumbar spine in RJP intake groups (ORL, ORH) were higher than that in OC group (p < 0.05 and p < 0.01) in RJP intake volume dependent manner. BMD of tibial proximal metaphysis and diaphysis in RJP intake groups were also higher than these in OC group (p < 0.01 and p < 0.01 / p < 0.05 and p < 0.001). In addition, breaking force of femur in RJP intake groups were significantly increase compared with that in OC group (p < 0.001 respectively). [Conclusion] These findings indicate that RJP contribute to prevent sex hormone related bone abnormality.

• Current Optics and Photonics
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• 제8권3호
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• pp.246-258
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• 2024

In aerospace and energy engineering, the reconstruction of three-dimensional (3D) temperature distributions is crucial. Traditional methods like algebraic iterative reconstruction and filtered back-projection depend on voxel division for resolution. Our algorithm, blending deep learning with computer graphics rendering, converts 2D projections into light rays for uniform sampling, using a fully connected neural network to depict the 3D temperature field. Although effective in capturing internal details, it demands multiple cameras for varied angle projections, increasing cost and computational needs. We assess the impact of camera number on reconstruction accuracy and efficiency, conducting butane-flame simulations with different camera setups (6 to 18 cameras). The results show improved accuracy with more cameras, with 12 cameras achieving optimal computational efficiency (1.263) and low error rates. Verification experiments with 9, 12, and 15 cameras, using thermocouples, confirm that the 12-camera setup as the best, balancing efficiency and accuracy. This offers a feasible, cost-effective solution for real-world applications like engine testing and environmental monitoring, improving accuracy and resource management in temperature measurement.

• Applied Biological Chemistry
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• 제22권1호
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• pp.28-32
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• 1979

증산되고 있는 한국산 온주계통 감귤의 품질향상을 도모하여 새로운 수요를 개발하기 위한 목적의 일환으로 제주산 감귤의 품종별 가공특성 조사를 실시하였다. 1. 과실 맛의 주체라고 할 수 있는 당도는 $9.0{\sim}10.0^{\circ}Bx$였고 산도는 $1.43{\sim}l.70%$로써 당산비는 $5.3{\sim}6.6$수준으로 비교적 낮은 품질 수준을 나타냈다. 2. 감귤 통조림의 백탁 현상의 원인이라고 알려진 과육의 hespeidin 함량은 조생종에 비하여 만생종으로 갈수록 낮아져 45mg%정도였다. 3. 외피율은 만생종이 될수록 높아져서 25%정도였고 착즙율은 50%이었다. 그러므로 저장에는 만생종이 유리하며 착즙율은 품종간에 큰 차이가 없었다. 4. 착즙액의 비중은 평균 1.040정도였고 혼탁도는 만생종이 될수록 높은 흡광도를 보였다. vit. C 및 hesperidin 함량은 $25{\sim}30mg%$를 유지하였다.

• 한국화재소방학회논문지
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• 제25권3호
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• pp.51-56
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• 2011

도로터널에서의 미분무수 소화시스템의 화재진압 특성을 조사하기 위해 실물 터널 화재 실험을 수행하였다. 적용된 소화시스템은 압력이 3.5 bar인 저압 물분무 소화설비와 60 bar인 고압 미분무수 소화시스템이다. 미분무수 소화시스템은 물분무 소화시스템의 1/6 만큼의 소화용수량을 사용한다. 화원 (fire source)은 실물 승용차와 유류화재를 모사한 화원면적 $1.4m^2$의 헵탄 연료 팬 화재로 구성하였다. 터널 내의 환기조건을 구현하기 위해 실물모형 터널의 한쪽 끝단에 유속(0.9~3.8 m/sec 범위) 발생장치를 설치하였으며, 화원에서 하류 방향으로 터널 내 온도분포는 K-type 열전대 트리를 사용하여 측정하였다. 실험 결과 고압 미분무수 소화시스템은 B급 화재의 경우 저압 물분무 시스템과 동등한 수준의 냉각효과를 보였다.

• 대한간호학회지
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• 제51권1호
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• pp.5-14
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• 2021

Purpose: This study aimed to investigate sub-health status (SHS) of people living in China during the Coronavirus disease 2019 (COVID-19) COVID-19 pandemic. COVID-19 is a severe acute respiratory syndrome coronavirus (SARS-CoV) infection-induced acute infectious disease, which is featured by universal susceptibility and strong infectivity, and SHS (a status of low quality health) refers to a status of low-quality health. COVID-19 has gradually developed into a global pandemic, making the public in a high stress situation in physiological, psychological and social states in the short term. Methods: From March 6 to 11, 2020, a large-scale cross-sectional survey was conducted by convenient sampling, and SHS assessment scale was used in the questionnaire. The ordinal logistic regression analysis was used to identify the factors affecting SHS. Results: In this study, 17,078 questionnaires were delivered with 16,820 effective questionnaires collected, and 10,715 subjects (63.7%) were found with SHS, with moderate SHS primarily. Physiological sub-scale scored the highest, followed by psychological and social sub-scales. Ordinal logistic regression analysis indicated that man, only-child, workers and farmers were risk factors of SHS. Protective factors of SHS included living in rural areas and townships, laid-off retirees and education degree. Conclusion: It shows many people in China place in a poor health status during COVID-19 pandemic. It is necessary that relevant departments pay more attention to people with poor health such as men, only-child, urban people, workers and farmers, and groups with high education degree during and after pandemic stabilization.