• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1123-1129
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• 2015

A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time-consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.

• Journal of The Korean Association For Science Education
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• v.37 no.4
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• pp.651-658
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• 2017

The purpose of this study is to analyze the invention-related content of foreign science curricula and investigate the perception of science educators about the degree of relevance between science curriculum and invention. For the analysis of foreign science curricula, we investigated the programs of 10 nations, including the US, Canada, UK, Japan, Australia, Singapore, New Zealand, France, Finland and China. To analyze the relevance between Korean science curriculum and invention, we examined common topics such as science, integrated science, and science inquiry experiment, and investigated that the elements related to invention education were included in each 'achievement standard' and 'teaching and evaluation methods'. Science educators including science teachers were asked to evaluate the degree of relevance of invention education. The results were as follows. First, science curricula in many countries contained invention-related content. Second, science educators recognized that invention education was related to science curriculum, but the systematic connection was insufficient. Third, because it is mainly limited to the results of designing and device design, they recognized that the relevance of invention education, which focuses on various processes such as problem design, inventive techniques and intellectual property, was not revealed. Therefore, it is necessary to be process-oriented when developing invention education teaching-learning methods and related materials in science education for the future.

• Journal of the Korean Magnetics Society
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• v.22 no.2
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• pp.49-57
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• 2012

From among the NDT (Non-Destructive Testing) methods, the MFL (Magnetic Flux Leakage) PIG (Pipeline Inspection Gauge) is especially suitable for testing pipelines because the pipeline has high magnetic permeability. MFL PIG showed high performance in detecting the metal loss and corrosions. However, MFL PIG is difficult to detect the crack which occured by exterior-interior pressure difference in pipelines and the shape of crack is very long and narrow. Therefore, the new PIG is needed to be researched and developed for detecting the cracks. The CMFL (Circumferential MF) PIG performs magnetic fields circumferentially and can maximize the magnetic flux leakage at the cracks. In this paper, CMFL PIG is designed and the distribution of the magnetic fields is analyzed by using 3 dimensional nonlinear finite element method (FEM). By Simulating and Measuring the magnetic leakage field, it is possible to detect of axial cracks in the pipeline.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.2
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• pp.149-158
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• 2013

L-ascorbic acid, the representative antioxidants, has a great effect on skin whitening, collagen synthesis, and anti-aging, but has low oxidative stability during storage. Therefore, in this study, thermal and oxidation properties of L-ascorbic acid under various storage conditions (powder, aqueous phase, changes of temperature, UV-irradiation, and inflow of external air etc.) were investigated. And the storage stability of ingredient was validated in the double-spaced pouch by analysing oxidation properties under each storage conditions (powder phase and blended with essence). In oder to analyze the thermal properties, TGA, DSC, and FT-IR analysis were carried out and UV-visible spectrophotometer & redox titration were used in parallel for oxidation property analyses. From the result of experiment, L-ascorbic acid was oxidized fast when it contained lots of metallic ion, hydroxy ion in aqueous solution under high temperature, UV-irradiation & inflow external air, whereas it was not oxidized for a long time when it was stored as pure powder although it has same condition as heating up, UV-irradiation & inflow external air. Based on this result, retention period of cosmetics which is using L-ascorbic acid, less stable material in oxidation can be innovatively increased when using double-spaced pouch that is designed and produced for separating storage of active ingredients.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.249-255
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• 2010

Methods of the characteristics evaluation of turbo-molecular pumps (TMP) are well-defined in the international measurement standards such as ISO, PNEUROP, DIN, JIS, and AVS. The Vacuum Center in the Korea Research Institute of Standards and Science (KRISS) has recently designed, constructed, and established the integrated characteristics evaluation system of TMPs based on the international documents by continuously pursuing and acquiring the reliable international credibility through measurement perfection. The measurement of TMP pumping speed is normally performed with the throughput and orifice methods dependent on the mass flow regions. However, in the UHV range of the molecular flow region, the high uncertainties of the gauges, mass flow rates, and conductance are too critical to precisely accumulate reliable data. In order to solve the uncertainty problems of pumping speeds in the UHV range, we introduced a SRG with 1% accuracy and a constant volume flow meter (CVFM) to measure the finite mass flow rates down to $10^{-1}$ Pa-L/s with 3% uncertainty for the throughput method. In this way we have performed the measurement of pumping speed down to $10^{-4}$ Pa with an uncertainty of less than 6% for a 1000 L/s TMP. In this article we suggest that the CVFM has an ability to measure the conductance of the orifice experimentally with flowing the known mass through the orifice chambers, so that we may overcome the discontinuity problem encountering during introducing two measurement methods in one pumping speed evaluation sequence.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.3
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• pp.229-236
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• 2012

This experiment was conducted to evaluate agronomic characteristics and forage productivity of italian ryegrass cultivars at Seongju in the Kyeongbuk from 2010 to 2012. The experiment was arranged in randomized complete block design with three replications. Italian ryegrass cultivars were seeded on Oct. 12 in 2010 and Oct. 3 in 2011. The early-medium maturing cultivars were harvested on 29 Apr. and the medium late ones were harvested on 4 May in 2011. In 2012, the early-medium cultivars were harvested on 28 Apr. and medium late ones were harvested on 12 May. DM (dry matter) yield of the early-medium maturing cultivars 'Yeonbong3', 'Seongnong', 'Winter Hawk', 'Pride' and 'Kowinnearly' was 9,850, 9,778, 9,486, 9,363 and 9,267 kg/ha and DM yield of those were significantly higher (p<0.05) than other seven cultivars or ones. DM yield of the medium-late maturing cultivars 'Tetragold', 'Hwasan 101', 'Jumbo', 'Sungrazer', 'Master', 'SelectIV' and 'KB Royal' was 9,542, 9,492, 9,103, 8,981, 8,903, 8,870 and 8,681 kg/ha and DM yield of those were higher (p<0.05) than other three. Cold tolerance for 'Hwasan 101' was higher than others, in medium-late maturing cultivars. According to the results obtained from this study, it is suggested that early-medium maturing cultivars would be recommendable for DM production.

• The Journal of Engineering Geology
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• v.27 no.2
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• pp.133-141
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• 2017

In this study, filter conditions by difference in grading between core material and filter material used for dam construction was applied as evaluation condition for surrounding ground conditions near excavation site in a bid to identify the risk of land subsidence resulting from the erosion of soil particles. To that end, filter conditions proposed for the test was evaluated and the risk of land subsidence depending on grain size conditions was also evaluated using the filter conditions developed by COE. Consequently, evaluation diagram that can be used to determine the risk of land subsidence using grain size conditions obtained from ground investigation data was developed, which is expected to help evaluate the possibility of land subsidence depending on changes to the stratum. To simulate the particle flow process, PFC3D program was used. It's not only intended to determine the land subsidence pattern caused by falling ground water level but also predict and evaluate the land subsidence caused by soil erosion using grain size condition which can be verified by numerical analysis approach.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.11a
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• pp.32-37
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• 1999

본 연구는 컨조인트 분석기법을 이용하여 의자의 물리적 적합도를 분석, 평가하여 사용자가 선호하는 최적의 의자를 제시하고자 하는데 목적이 있다. 컨조인트 분석기법은 Marketing 분야에서 주로 많이 쓰여온 분석 방법으로서 제품의 중요한 속성들을 찾아내어 다양한 종류의 제품들에 대한 고객의 선호도를 분석하는 방법이다. 이러한 컨조인트 분석기법은 제품개발과 평가의 측면에서 매우 큰 가능성이 있음에도 불구하고 마켓팅 이외의 분야에서는 거의 적용되자 않고 있는 실정이다. 따라서 본 연구에서는 의자의 물리적 적합성 연구에 이 컨조인트 분석을 이용하여 그 적용의 가능성을 알아보고자 하였다. 또한 이러한 적합성 연구에 컨조인트 분석기법이 타당한 분석기법인지 비교하기 위해 분산분석의 기법도 병행하여 실시하였다. 문헌 조사와 전문가 의견 수렴을 통하여 선행연구에서 추출된 의자의 물리적 적합도 요소인 안정성, 여유성, 적합성, 안락성등 4개의 적합도 요소를 채택하여 종속변수로 사용하였다. 또한 의자 자체의 설계 요소에 해당하는 휴먼인터페이스 요소(HIE)는 높이 조절 여부, 팔걸이 유무, Tilting 유무의 3가지 속성을 선택하여 독립변수로 사용하였다. 분석에 사용된 의자는 각 속성을 특징적으로 대표하는 8개의 의자들로서 구성하였고 63명의 피험자를 사용하여 실험하였다. 분석의 결과는 안정성에 가장 큰 영향을 주는 속성은 높이조절(HC)로서 남자와 여자 모두 높이조절 기능이 없을 때 안정성을 느낀다는 결과가 나왔다. 여유성에 영향을 주는 가장 큰 요인은 남자는 높이조절 기능이 있을 때, 여자는 팔걸이가 있을 때 여유성이 있다고 판단하였으며, 인체적합성에 영향을 주는 요인은 남자와 여자 모두 Tilting 기능이, 안락성에 영향을 주는 주요인은 남자는 Tilting 기능이 있을 매, 여자는 높이조절 기능이 있을 때인 것으로 나타났다.감, 강연성, 회복성, 수분특성, 밀도감이었으며, 요인들로 설명되는 누적분산값은 67.18%였다.주관적 평가의 결과와 객관적 평가 결과를 이용해 마직물의 태를 평가하는 산출식을 제시하였다. 태 평가치의 경우 16가지 특성치를 모두 넣는 방법과 stepwise 방법, 또 Kawabatark 사용한 순차적 군 회귀법의 세가지 방법의 회귀식 중 16가지 특성치를 모두 넣는 방법의 결정계수가 가장 높았다.tosterone농도는 107.7$\pm$12.0 pmol／l이었고, 남성의 타액내 농도는 274.2$\pm$22.1 pmol／l이었다. 이상의 결과로 보아 본 연구에서 정립된 EIA 방법은 RIA를 대신하여 소규모의 실험실에서도 활용할 수 있을 것으로 사려된다.또한 상실기 이후 배아에서 합성되며, 발생시기에 따라 그 영향이 다르고 팽창과 부화에 관여하는 것으로 사료된다. 더욱이, 조선의 ${\ulcorner}$구성교육${\lrcorner}$이 조선총독부의 관리하에서 실행되었다는 것을, 당시의 사범학교를 중심으로 한 교육조직을 기술한 문헌에 의해 규명시켰다.nd of letter design which represents -natural objects and was popular at the time of Yukjo Dynasty, and there are some documents of that period left both in Japan and Korea. "Hyojedo" in Korea is supposed to have been influenced by the letter design. Asite- is also considered to have been "Japanese Letter Jobcheso." Therefore, the purpose of

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.106-114
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• 2017

This study was a one-group pre-post test design experimental investigation conducted to evaluate the effects of problem-based learning by type of learning in nursing students. The subjects of the study were 125 senior students in the Department of Nursing Science at a single university located in A. City, and the study was conducted for eight weeks from April 18 through June 10, 2016. Data analysis consisted of descriptive statistics, ANOVA, ${\chi}^2$-tests and t-tests. Most nursing students underwent converger type of learning, and after problem-based learning, their learning flow, problem-solving ability and critical thinking disposition increased significantly. In problem-based learning by type of learning, the problem-solving ability was significantly higher in the converger type than in the accommodator type, and there were no significant differences in learning flow and critical thinking disposition; however,in all types of learning, learning flow and critical thinking disposition increased. Since these results suggest that teaching and learning strategies should be set up for each type of learning, it is necessary to seek plans for teaching and learning strategies to make up for the weak points and strengthen the strong points by each type of learning when applying the problem-based learning method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1399-1410
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• 2009

It is a method to treat pain using medication, neurotomy, and surgery. And acupuncture, ultrasound, electric treatment, and magnetic treatment are applied as a alternative physiotherapy. Electronic therapy is useful but it can be affected by impedance of skin or subcutaneous tissue. So, percutaneous stimulation is leading therapy, that is very randomly. We developed the system which can stimulate parts of acupuncture point noninvasively using the focused magnetic field. And we designed the magnetic stimulation electrode which is considered efficiency of the magnetic stimulation. It can make similar stimulation with manual acupuncture. To confirm the availability and reliability we compared Meridian Electronic Potential(MEP) change between manual acupuncture and magnetic stimulation. From this result, we found out the MEP changes of manual acupuncture and magnetic stimulation were similar. And there were various response properties as changes of stimulation method, intensity, and frequency. Also, the MEP change can be induced by electromagnetic stimulation. We confirmed that it is possible to use electromagnetic stimulation as a acupoint stimulation or pain treatment instrument.