• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1466-1473
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• 2012

Soft icecream is made by scraping an ice formed on the inside of the cylindrical evaporator, where R-404A is evaporating in the annulus. The heat transfer characteristics of the refrigerant evaporation and those during icecream formation were experimentally investigated. Results show that the refrigerant-side heat transfer coefficients are highly dependent on the location in the evaporator due to the complex annulus configuration. The heat transfer coefficient at the inlet is generally lower than those of other locations. The average heat transfer coefficient increases as heat flux increases or saturation temperature decreases. A correlation is developed to predict the refrigerant-side heat transfer coefficient. The icecream-side heat transfer coefficient oscillates continuously due to the periodic removal of ice formed on the surface. The average heat transfer coefficient during icecream formation is approximately 280 W/$m^2K$, and that during single-phase cooling increased from 150 W/$m^2K$ to 250 W/$m^2K$.

• The Journal of Korean Association of Computer Education
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• v.23 no.2
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• pp.73-82
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• 2020

The main purpose of this study was to analyze the general informatization situation of North Korean defectors and to study the characteristics and needs of the learners in order to provide the directions of information education for them. The results of the study showed the following characteristics of the North Korean defectors: They are slow learners due to the fear of new devices, have difficulty in learning due to the unfamiliar language of information and English, and indifferent when the situation is not related to themselves. Based on these learner characteristics and needs, this study suggests the strategies of step-by-step repetition, use of North and South Korean dictionary of the information terminology, apply job-centered and communication abilities, and suggested a four-element STEP model. Raising the level of informatization of North Korean defectors will help establish a successful settlement to South Korea. This will be a valuable foundation and a stepping stone for the future unification of Korea.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.60-60
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• 1999

단결정 다이아몬드의 열전도도는 약 22W/cm.K로 열전도도가 가장 큰 물질로 알려져 있으며, 비저항은 10$\Omega$.cm 이상의 높은 값을 갖는다. 대부분 열전도도가 큰 것으로 알려진 물질들은 Cu, Ag 등과 같이 전자의 흐름에 의하여 열이 전도되기 때문에 큰 전기전도도를 함께 갖는 것일 일반적이다, 그러나, 다이아몬드는 빠른 phonon의 이동에 의하여 열전도가 이루어지므로 전기적으로 절연 특성을 갖으면서도 큰 열전도가 가능하다. 단결정 다이아몬드는 고방열 절연체로서 이상적인 물질 특성을 보여준다. 전기절연성을 갖는 열전도층으로 다이아몬드를 이용하기 위해서는 저가로 제조가 용이한 화학기상증착법을 이용하여야 한다. 화학기상증착법으로 제조된 다결정 다이아몬드 박막의 열전도도는 약 21W/cm.K로 여전히 매우 높은 값을 갖는 것으로 알려져 있지만, 비저항 값은 인위적으로 도핑을 전혀 하지 않은 상태에서도 106$\Omega$.cm 정도의 낮은 값을 갖는다. 전혀 도핑을 하지 않았음에도 전도성을 갖는 특이한 특성을 다결정 다이아몬드가 보여 주고 있으므로 이에 대한 연구는 주로 전기 전도성을 갖는 특이한 특성을 다결정 다이아몬드가 보여주고 있으므로 이에 대한 연구는 주로 전기전도성의 원인을 규명하는데 집중되고 있다. 아직 명확한 전도 기구는 제안되고 있지 못하지만 전도성의 원인은 수소와 관련이 있고 전도는 표면을 통하여 이루어진다는 것이다. 산(acid)을 이용하여 다결정 다이아몬드 박막을 세척하면 전기 전도성이 사라지고 높은 저항값을 갖는 박막을 얻게 되는데 박막을 세척하는 공정은 박막의 표면만을 변호시키므로 표면에 있던 전기전도층이 용액 처리를 통하여 제거되므로 전도성이 사라진다고 생각하는 것이다. 그러나, 본 연구에서는 두께가 두꺼울수록 저항값이 증가하는 것이 관찰되었고 기존의 측정방식인 수평적인 저항 측정법에 대하여 수직적 방향으로 저항을 측정하면 저항값이 1/2 정도 작게 측정되었다. 다결정 다이아몬드에서 표면을 통하여 전류가 흐른다면 박막의 두께에 따른 변화가 나타나지 않아야 하고 수직적인 전류 측정법이 오히려 더 큰 저항을 보여주어야 한다. 기존의 표면 전도 모델로는 설명되지 못하는 현상들이 관찰되었고 정확한 전기 전도 경로를 확인하기 위하여 전해 도금법으로 금속들이 석출되는 모습을 관찰하였다. 이 방법을 통하여 다결정 다이아몬드에서 전류는 결정입계를 통하여 전도됨을 알 수 있었다. 온도에 따른 다결정 다이아몬드의 전기전도도 변화를 관찰하였고 이로부터 활성화 에너지 값을 구할 수 있었다. 다결정 다이아몬드의 전도도는 온도에 따라서 0.049eV와 0.979eV의 두 개의 활성화 에너지를 갖는 구간으로 나뉘어졌다. 이로부터 다결정 다이아몬드에는 활성화 에너지 값이 다른 두 종류의 defect level이 형성되는 것으로 추정할 수 있고 이 낮은 defect level에 의하여 전도성을 갖는 것으로 생각된다.

• The Journal of Korean Association of Computer Education
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• v.21 no.4
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• pp.39-52
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• 2018

There has been a lot of interest in flipped learning, but lacked practical research to support the faculty developing flipped learning courses in higher education institutions. The purpose of this study is to develop a consulting model for developing a flipped learning course that can be practically used by institutions such as center for teaching and learning that support faculty teaching to improve the quality of instruction. A 'Coaching based on flip learning course development consulting model' was derived through literature review and expert feedback. The 8-step model is as follows: 1) survey of class development, 2) course orientation, 3) flipped learning, 4) expert class analysis, 5) flipped learning coaching, 6) flipped learning operation, 7) instructor reflection, and 8) feedback and revision. Based on the results of this study, it is possible to provide professional and practical guide systematically, and also help to improve quality of lesson.

• Korean journal of communication and information
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• v.27
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• pp.35-62
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• 2004

This study examined how the three major newspapers covered the press reform movement in Korea. Despite that the NGOs and Korean government keep trying to reform the market and structure of the newspapers, the targeted newspapers argue that they are unjustly accused of the dominance of the press market made by the readers' choice. Using frame analysis and discourse analysis, this study analyzed the news coverage on the press reform for 6 months and revealed that these major newspapers presumed to be targeted were totally challenging against the press reform by means of flaming of news and using news discourse. The ways of challenge were, firstly they appealed to the readers that the press reform is the press suppress so that they have to fight against this unacceptable pressure. And secondly, they report the news selectively for their own interests by elaborating, magnifying, or reducing the facts. Thirdly, they attack the government policies and major figures leading the press reform by letting the outside columnists favorable to their own standing point. And finally, they conduct the poll on and off and report what they want according to their self interests.

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.423-432
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• 2018

The purpose of this study was to investigate the differences in upper and lower strengths and symmetry between upper body injury group, lower body injury group and non-injury group of bowling athletes. The subjects were the upper body injury group (UG), n = 16, the low body injury group (LG), n = 8, the non injury group, [NG], n = 15). The isometric strength of the bowler was measured using Manual Muscle Tester 01165 (Lafayette Instrument Company, USA) and the symmetry index (SI) was calculated. The results were as follow. The symmetry index of hip extension strength and hip external rotation strength was statistically larger in NG than LG (p <.05). The above results suggest that lower body strength and bilateral symmetry was closely related to injuries of the lower body. In order to prevent injury of the bowler, strengthening of lower body strength and symmetrical training are needed.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.3
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• pp.95-103
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• 1998

This paper deals with a problem occuring in recognition of tactile images due to the effects of imposed force at a me urement moment. Tactile image of a contact surface, used for recognition of the surface type, varies depending on the forces imposed so that a false recognition may result in. This paper fuzzifies two parameters of the contour of a tactile image with the membership function formed by considering the imposed force. Two fuzzifed paramenters are fused by the average Minkowski's dist; lnce. The proposed algorithm was implemented on the multisensor system cnmposed of an optical tact le sensor and a 6 axes forceltorque sensor. By the experiments, the proposed algorithm has shown average recognition ratio greater than 869% over all imposed force ranges and object models which is about 14% enhancement comparing to the case where only the contour information is used. The pro- ~oseda lgorithm can be used for end-effectors manipulating a deformable or fragile objects or for recognition of 3D objects by implementing on multi-fingered robot hand.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.461-467
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• 1989

The effect of $CO_2$ concentration on the post-harvest physiology and quality of Shiitake mushroom (Lentinus edodes) were investigated during CA storage. The respiratory rates of the mushroom stored in CA conditions were abruptly increased in proportion to $CO_2$ concentration after 40 days, and then declined, while that of the mushroom in air was continuously decreased throughout storage period. Large amounts of ethanol and acetaldehyde were produced from the 20 days CA stored mushrooms. The least changes in 5'-GMP content and electrophoresis pattern of protein in the mushroom were observed at $CO_2$ concentration of 2% during storage. Based on the changes in quality factors of the mushroom during storage, it could be concluded that $CO_2$ concentration of 2% with fixed $O_2$ concentration of 2% was more effective in extension of the freshness than any other $CO_2$ level in this experiment.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.27-39
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• 2012

The purpose of this study is to develop and suggest u-project teaching and learning model in order to effectively practice multidisciplinary and practical green growth conversion education, In order to achieve the purpose of study, the researchers conducted surveys to middle and high school teachers (189), teachers-to-be (285), and middle school students (358) on green growth perception, and analyzed relation between the ten green growth strategic directions and the 2007 and 2009 curricula. The extraction of the teaching and learning contents for the ubiquitous green growth conversion education and the development of a TUGG (Teaching Ubiquitously for Green Growth) model that is suitable for middle school application were also pursued. This study will increase the understanding of the necessity and propriety of green growth and also promote multidisciplinary and practical green growth conversion education.

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.521-528
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• 1993

Ni-graphi~e composite powders were prepared by reduct ion of $Ni^{++}$ from arnmoniacal nickel sulfate solution on graphite core by hydrogen gas at elevated temperature and pressure. Effect of coating catalyst. Anthraquinone $(C_6H_4COC_6H_4 CO)$, on the reduction rate and the properties of nickel layer were investigated by SEM, X-ray, size and chemical analysis. 1nduct.ion period, a time lag between the ~njection of hydrogen gas and the start of the reduction, was 22 to 70 mins and was affected by the size and amount of Anthraquinone. Kickel layer deposited on the surface of graphite core material was composed of nickel nodules whose sizes were different with vari~ ous reduction conditions. Minimum diameter of nickel nodules was about 2-3$\mu \textrm m$.