• 한국직업건강간호학회지
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• 제14권2호
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• pp.118-128
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• 2005

A cross-sectional study was conducted to examine the prevalence and related factors of musuculoskeletal symptoms in automobile manufacturing, steel processing, electric assembly line, and wood processing industries. A study subjects were 3,434 workers from small and medium scale companies of Incheon. Walk-through surveys were performed from Feb. of 2004 to Oct. of 2004 to investigate various physical work factors. Symptom prevalence rate by related factors was that women worker showed higher rate than man, and married person was higher than single person. For the working year, group of person who were working less than 3 year showed the highest rate. However, the group of person who were working more than 10 hour per day showed the highest rate. For the total subjects, prevalence of symptoms by body area was as follows: shoulder symptoms were the most frequently reported symptoms(253 person, 7.0%), followed by back(155 person, 4.5%), hand or fingers (136 person, 4.0%), lower extremities(131 person, 3.9%), neck(108 person, 3.1%), and elbow symptoms(97 person, 2.8%).

• Journal of Gynecologic Oncology
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• 제29권6호
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• pp.90.1-90.12
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• 2018

Objective: We performed small-scale mutation and large genomic rearrangement (LGR) analysis of BRCA1/2 in ovarian cancer patients to determine the prevalence and the characteristics of the mutations. Methods: All ovarian cancer patients who visited a single institution between September 2015 and April 2017 were included. Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), and long-range polymerase chain reaction (PCR) were performed to comprehensively study BRCA1/2. The genetic risk models BRCAPRO, Myriad, and BOADICEA were used to evaluate the mutation analysis. Results: In total, 131 patients were enrolled. Of the 131 patients, Sanger sequencing identified 16 different BRCA1/2 small-scale mutations in 20 patients (15.3%). Two novel nonsense mutations were detected in 2 patients with a serous borderline tumor and a large-cell neuroendocrine carcinoma. MLPA analysis of BRCA1/2 in Sanger-negative patients revealed 2 LGRs. The LGRs accounted for 14.3% of all identified BRCA1 mutations, and the prevalence of LGRs identified in this study was 1.8% in 111 Sanger-negative patients. The genetic risk models showed statistically significant differences between mutation carriers and non-carriers. The 2 patients with LGRs had at least one blood relative with breast or ovarian cancer. Conclusion: Twenty-two (16.8%) of the unselected ovarian cancer patients had BRCA1/2 mutations that were detected through comprehensive BRCA1/2 genetic testing. Ovarian cancer patients with Sanger-negative results should be considered for LGR detection if they have one blood relative with breast or ovarian cancer. The detection of more BRCA1/2 mutations in patients is important for efforts to provide targeted therapy to ovarian cancer patients.

• Smart Structures and Systems
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• 제22권1호
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• pp.41-55
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• 2018

Damping ratio and frequency have influence on dynamic serviceability or instability such as vortex-induced vibration and displacement amplification due to earthquake and critical flutter velocity, and it is thus important to make determination of damping ratio and frequency accurate. As bridges are getting longer, small scale model test considering similitude law must be conducted to evaluate damping ratio and frequency. Analysis conditions modified by similitude law are applied to experimental test considering different scale ratios. Generally, Nyquist frequency condition based on natural frequency modified by similitude law has been used to determine sampling rate for different scale ratios, and total time length has been determined by users arbitrarily or by considering similitude law with respect to time for different scale ratios. However, Nyquist frequency condition is not suitable for multimode system with noisy signals. In addition, there is no specified criteria for determination of total time length. Those analysis conditions severely affect accuracy of damping ratio. The focus of this study is made on the determination of minimum analysis conditions for different scale ratios. Influence of signal to noise ratio is studied according to the level of noise level. Free initial value problem is proposed to resolve the condition that is difficult to know original initial value for free vibration. Ambient and free vibration tests were used to analyze the dynamic properties of a system using data collected from tests with a two degree-of-freedom section model and performed on full bridge 3D models of cable stayed bridges. The free decay is estimated with the stochastic subspace identification method that uses displacement data to measure damping ratios under noisy conditions, and the iterative least squares method that adopts low pass filtering and fourth order central differencing. Reasonable results were yielded in numerical and experimental tests.

• ALGAE
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• 제34권1호
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• pp.57-70
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• 2019

DNA metabarcoding is currently used for large-scale taxonomic identification to understand the community composition in various marine ecosystems. However, before being widely used in this emerging field, this experimental and analytic approach still has several technical challenges to overcome, such as polymerase chain reaction (PCR) bias, and lack of well-established metabarcoding markers, a task which is difficult but not impossible to achieve. In this study, we present an adapted PCR-free small-organelles enriched metagenomics (SoEM) method for marine biodiversity assessment. To avoid PCR bias and random artefacts, we extracted target DNA sequences without PCR amplification from marine environmental samples enriched with small organelles including mitochondria and plastids because their genome sequences provide a valuable source of molecular markers for phylogenetic analysis. To experimentally enrich small organelles, we performed subcellular fractionation using modified differential centrifugation for marine environmental DNA samples. To validate our SoEM method, two marine environmental samples from the coastal waters were tested the taxonomic capturing capacity against that of traditional DNA metabarcoding method. Results showed that, regardless of taxonomic levels, at least 3-fold greater numbers of taxa were identified in our SoEM method, compared to those identified by the conventional multi-locus DNA metabarcoding method. The SoEM method is thus effective and accurate for identifying taxonomic diversity and presents a useful alternative approach for evaluating biodiversity in the marine environment.

• 정보교육학회논문지
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• 제21권5호
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• pp.595-605
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• 2017

본 논문에서는 지역규모에 따라 초등학생의 ICT 리터러시 점수가 차이나는 원인을 분석하였다. 선행연구에 따르면 2016년 측정된 초등학생들의 ICT 리터러시 점수는 대도시, 중소도시, 읍면지역 순으로 높게 나타났다. 이에 본 논문에서는 그 원인을 알아보고자 지역규모별 초등학생들의 평소 ICT 활용 습관 차이와 ICT 리터러시 점수를 비교하여 분석하였다. 그 결과, 지역규모가 클수록 초등학생들의 ICT 리터러시 점수가 높은 원인은 큰 지역에 거주하는 학생들이 작은 지역에 거주하는 학생들보다 가정에서 컴퓨터를 사용하는 기회가 더 많고 컴퓨터를 이용하여 학습 활동을 더 많이 하며, 정보(컴퓨터)교육을 받은 경험도 더 많기 때문인 것으로 판단되었다. 이에 따라 본 논문에서는 지역 간 초등학생의 정보격차를 줄이기 위하여 지역규모가 작은 저소득계층의 자녀들에 대한 컴퓨터 지원과 함께 가정에서 컴퓨터를 활용한 학습 활동 안내 그리고 정보(컴퓨터)교육 기회 확대 등을 종합적으로 지원할 것을 제안하였다.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.1-8
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• 2018

본 연구는 Siphon Breaker Simulation Program(SBSP)을 이용하여 소규모 사이펀 차단기 실험장치를 설계 및 제작하고, 실험 수행 후 그 결과를 이용하여 다양한 규모의 사이펀 차단기에 대한 SBSP의 적용 가능성을 평가하기 위해 진행되었다. 실험장치 설계를 위하여 C factor와 Chisholm B 계수, Undershooting Height(UH)에 대한 시뮬레이션 결과값을 SBSP로 도출하였다. 실험장치의 중요파트는 upper tank, lower tank, downcomer, Siphon Breaker Line(SBL) 등이며, upper tank는 넓이 $0.09-m^2$, 높이 0.65-m의 크기로 제작되었고, downcomer 높이는 1.6-m로 제작되었다. 실험결과 분석을 위하여 압력계, 차압계, 전자저울이 사용되어 압력과 차압, 유량에 대한 정보를 도출하였다. 실험에서 사용된 실험변수는 Loss Of Coolant Accident(LOCA) 크기와 SBL 크기이며, LOCA는 30-mm와 38-mm에 대해서, SBL은 6/16-inch와 8/16-inch에 대해서 실험이 진행되었다. 실험의 결과로 유량과 압력, 그리고 UH를 도출하였으며, 실험결과를 SBSP의 시뮬레이션 결과와 비교, 분석하였다. UH 측면에서 SBSP가 수조의 총 높이 대비 2.5 %의 오차로 실험결과를 잘 예측하는 것을 관찰하였다. 그러므로 SBSP를 이용한 다양한 규모의 사이펀 차단기 설계가 가능한 것을 확인하였다.

• International Journal of Fluid Machinery and Systems
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• 제6권4호
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• pp.200-205
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• 2013

In order to investigate the characteristics of unsteady flow in a mixed flow pump guide vane under the small flow conditions, several indicator points in a mixed flow pump guide vane was set, the three-dimensional unsteady turbulence numerical value of the mixed flow pump which is in the whole flow field will be calculated by means of the large eddy simulation (LES), sub-grid scale model and sliding mesh technology. The experimental results suggest that the large eddy simulation can estimate the positive slope characteristic of head & capacity curve. And the calculation results show that the pressure fluctuation coefficients of the middle section in guide vane inlet will decrease firstly and then increase. In guide vane outlet, the pressure fluctuation coefficients of section will be approximately axially symmetrical distribution. The pressure fluctuation minimum of section in guide vane inlet is above the middle location of the guide vane suction surface, and the pressure fluctuation minimum of section in which located the middle and outlet of guide vane. When it is under the small flow operating condition, the eddy scale of guide vane is larger, and the pressure fluctuation of the channel in guide vane being cyclical fluctuations obviously which leads to the area of eddy expanding to the whole channel from the suction side. The middle of the guide vane suction surface of the minimum amplitude pressure fluctuation to which the vortex core of eddy scale whose direction of fluid's rotation is the same to impeller in the guide vane adhere.

• Tribology and Lubricants
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• 제24권1호
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• pp.27-33
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• 2008

A micro-impression creep machine was designed and developed, adopting a small punch in diameter of 150 um, displacement gage with an accuracy of sub-${\mu}m$ scale, and load-cell with an accuracy of mN scale in order to investigate creep behavior of small solder ball in diameter of less than 1 mm. Creep behavior of lead-free solder ball(Sn-3.0Ag-0.5Cu) in diameter of $760\;{\mu}m$ was investigated in the stress range of $8{\sim}60\;MPa$ and at $303\;K{\sim}393\;K$. The applied load became decreased slightly and continuously in the creep rate of $10^{-4}/s$ range during the current experiments. Also, the machine frame was so sensitive to the environmental temperature that nm scaled displacement recording was unstable according to the change in environmental temperature.

• 유통과학연구
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• 제15권1호
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• pp.43-49
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• 2017

Purpose - This study is to integrate organizational factors into UCD process. For this research purpose, we investigated the organizational factors which influence people behaviors in the context of user-centred design practice(UCP). And this study presents organizational culture, organizational learning and change management as the organizational factors. Especially, this study is to investigate how change management influences the relationship between the organizational culture/learning and UCD performance. Research design, data, and methodology - Using the survey methodology with a questionnaire, this study distributed the questionnaire to the experienced 112 practitioners of user-centred design practice in 52 Korean small and medium companies. The organizations differed in range and size from medium-scale, which is under 100 of employees, and to small-scale, which is from 100 to 500. Results - Organizational culture and organizational learning have positive effects on user-centred design practice performance as expected. And change management strengthens the positive relationship between organizational learning and user-centred design practice performance but has no effect on the relationship between organizational culture and user-centred design practice performance. Conclusions - This is the first empirical study of investigating and demonstrating some key organizational factors' relationships and UCD performance of an organization, which will support to institutionalize UCD within an organization, providing theoretical foundations.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.1052-1061
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• 2005

A small-scale loop heat pipe (LHP) with polypropylene wick was fabricated and tested for investigation of its thermal performance. The container and tubing of the system were made of stainless steel and several working fluids were tested including methanol, ethanol, and acetone. The heating area was $35\;mm\;{\times}\;35\;mm$ and nine axial grooves were provided in the evaporator to provide vapor passages. The pore size of the polypropylene wick inside the evaporator was varied from $0.5\; {\mu}m\;to\;25\;{\mu}m.$ The inner diameter of liquid and vapor transport lines were 2.0 mm and 4.0 mm, respectively and the length of which were 0.5 m. The size of condenser was $40\;mm\;(W)\;{\times}\;50\;mm\;(L)$ in which ten coolant paths were provided. Start-up characteristics as well as steady-state performance was analyzed and discussed. The minimum thermal load of $10\;W\;(0.8\;W\;/cm^{2})$ and maximum thermal load of $80\;W\;(6.5\;W\;/cm^{2})$ were achieved using methanol as working fluid with the condenser temperature of $20^{\circ}C$ with horizontal position.