• Journal of Food Hygiene and Safety
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• v.26 no.1
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• pp.70-75
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• 2011

A new and improved analytical method involving alkaline pyridine extraction was proposed to quantity chlorophyll contents in syrup and candy type chlorella products. The performance of analytical method was compared with the conventional Korea food standard method which involves acetone extraction. The application of sonication chlorophyll extraction form alkaline pyridine sample was also explored. The analytical procedure was validated by evaluating accuracy, precision and reproducibility. For liquid samples, the pyridine extraction method showed higher accuracy and precision compared to acetone extraction method. The CV values of pyridine extract method and the acetone extraction method were 18.82 and 40.0, and the accuracy to theoretical values were 106.3% and 78.1%, respectively. When sonication extraction method was applied to the pyridine extraction, the precision was improved as indicated by reduced CV values from 18.82 to 11.36. The improved performance of pyridine-sonication extraction was also validated by recovery test of chlorophyll that was previously spiked into the sample matrix. For solid matrix, the pyridine extraction method showed better performance in analysis of chlorophyll in solid food matrix (CV = 7.05) compared to conventional acetone extraction method (CV = 30.0). However, the accuracy to theoretical values of pyridine and acetone extraction methods only showed only 62.7% an 40%, respectively. The relatively low accuracy of pyridine extraction method (62.7%) was improved to 99.4% by applying additional sonication extraction method. The improved performance of applying additional sonication extraction was validated by standard deviation, CV values and accuracy to theoretical values.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.143-152
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• 2016

To estimate the stability of a debris flow it is necessary to know the mass of surface soil, cohesion, slope, and friction angle. Given that the mass of surface soil is a function of soil thickness and mass density, it is important to obtain reliable estimates of soil thickness across a wide area. The objective of this paper is to estimate soil thickness using the elastic wave velocity with a new standard velocity. Tests are performed in debris-flow hazard areas, after which four profiles are selected to obtain the elastic wave velocity. Dynamic cone penetration tests are carried out to find the soil thickness at 18 points. The elastic wave velocity shows the area consists of 3~4 layers, and soil thicknesses are predicted by utilizing the new standard. The elastic wave velocity and dynamic cone penetration tests yield large differences in soil thickness. Therefore, this study shows that the new standard is useful not only in estimating soil thickness but also in improving the reliability of estimates of soil thickness.

• 대한공업교육학회지
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• v.34 no.1
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• pp.44-86
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• 2009

The major purposes of this study were 1) to present a desirable guideline for writers who would develop the new Introduction-to-Industry textbook through the comparative analysis of 4 different kinds of current Introduction-to-Industry textbooks, 2) to help educators, who make national college entrance exam in the vocational inquiry area, make good exam items with the results of the study, and 3) to offer effective methods of teaching and learning in the field of industrial education with them. Research method used in this study was mainly literature review with the scrutinization of the literature related to the Introduction-to-Industry textbooks. Results of this study showed that all textbooks compared do mostly comply with the national writer's specific guidelines for the Introduction-to-Industry textbooks. However there were varieties for the all textbooks in a sense of deployment balance for the contents of the textbook chapters. There were also considerable differences for the deployment of supplementary materials, evaluative materials, visual materials and etc. according to the characteristics of each textbook. The degree of the connectivity between the textbooks and the national college entrance exam in the area of the vocational inquiry was similar for the each textbook. However, it was not good enough for the students to study one textbook for the preparation of the exam in the vocational inquiry area because the problems in the exam were set in the range of covering the all different kinds of textbooks by the examiners.

• Journal of the Korean Geosynthetics Society
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• v.19 no.2
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• pp.13-21
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• 2020

In Korea, small reservoirs have been constructed for the supply of agricultural water, but most of them have been over 50 years from the year of construction. Aging agricultural reservoirs are being investigated for serious defects such as leaks and movements in slope, which are very vulnerable to safety. Accordingly, grouting methods are used to reinforce aging agricultural reservoirs in Korea. However, cement used as a grouting injection material consumes natural resources and generates a large amount of greenhouse gases during production. In addition, there is a problem that sufficient reinforcement is not made due to various factors such as the injection amount, the compounding ratio, the injection pressure, and etc. Therefore, due to these problems, the development of new materials and methods that can replace the grouting method and cement is required. In order to solve these problems, this study conducted an laboratory test on the surface stabilizer used to secure the stability of road and rail slopes. In addition, the program was analyzed and the reinforcing effect was examined when the surface stabilizer was used as reinforcement material for aging agricultural reservoir. As a result of the laboratory test, when the surface stabilizer is mixed, the increase of cohesion is possible up to 9% and there is no change in the friction angle. The results of the program analysis showed that the 1.0m reinforcement of slopes increased the factor of safety by 1.4 times, making it possible to reinforce the aging agricultural reservoir using surface stabilizers. And as a reinforcement method, it was analyzed that it is most appropriate to reinforce the slope and the bottom of slope simultaneously.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1777-1783
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• 2014

In this paper, we designed and fabricated a high-speed semiconductor sensor for use in power control devices and analyzed the characteristics with pulsed radiation tests. At first, radiation sensitive circular Si PIN diodes with various diameters(0.1 mm ~5.0 mm) were designed and fabricated using Si epitaxial wafer, which has a $42{\mu}m$ thick intrinsic layer. The reverse leakage current of the diode with a radius of 2 mm at a reverse bias of 30 V was about 20.4 nA. To investigate the characteristic responses of the developed diodes, the pulsed gamma-radiation tests were performed with the intensity of 4.88E8 rad(Si)/sec. From the test results showing that the output currents and the rising speeds have a linear relationship with the area of the sensors, we decided that the optimal condition took place at a 2 mm diameter. Next, for the selected 2 mm diodes, dose rate tests with a range of 2.47E8 rad(Si)/sec to 6.21E8 rad(Si)/sec were performed. From the results, which showed linear characteristics with the radiation intensity, a large amount of photocurrent over 60mA, and a high speed response under 350ns without saturation, we can conclude that the our developed PIN diode can be a good candidate for the sensor of power control devices.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.3
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• pp.215-224
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• 2013

It has been reported that certain ingredients added to cosmetics clog the skin pores and this can cause outbreaks of comedones which are the primary sign of acne leading to inflammatory acne. This research aims to establish objective evaluation criteria for non-comedogenic cosmetics suitable for acne prone skin. The research has been carried out to examine non-comedogenic test performed in foreign clinical institutions and to establish the evaluation method for detecting comedones outbreaks through repetitive closed back-patch test, Also, usability evaluation on face skin is performed additionally to the same subjects. The analysis of the comedones collected through repetitive closed back-patch test confirmed that the test products, moisturizer and sunscreen product, did not cause comedones. These results had no correlation with the analysis result of the comedones collected from face skin or visual evaluation of acne by Global Acne Grading System (GAGS) in face usability test. Additionally, Oil red O staining was performed on the collected comedones specimen for easy distinction of comedones from hair follicle in image analysis. The analysis result of stained specimen showed higher precision than that of non-stained specimen. This study established a new version of non-comedogenic test for cosmetics, whose objectivity and reliability were improved by inclusion of comedones staining step.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.31-39
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• 2013

In this study, performance of the post-installed anchor system was evaluated with reduced strength of concrete and anchor. One of the post-installed anchors was selected to performance evaluation. Concrete strength was reduced by freeze-thawing test, and the post-installed anchor strength was reduced by corrosion test. The post-installed Anchor was installed in concrete of freezing and thawing and original concrete, and corroded anchor was installed in original concrete only. Anchor diameter and installation depth of the anchor were the variable for each specimen. Performance of post-installed anchor system of each specimen was evaluated by pullout test. Anchor diameter and installation depth of anchor, it may affect the performance of the post-installed anchor system from the experimental test results. Fracture mode of each post-installed anchor system had occurred differently depending on the durability of concrete and anchor. The anchor pullout strength from the experimental test results was used in order to compare with the results of CCD (Concrete Capacity Design) method, and CCD equation was modified. Modified equation was able to predict the anchor pullout strength of post-installed anchor system in Original concrete and freezing and thawing of concrete.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.3
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• pp.10-14
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• 1987

우리나라는 이제 그동안의 꾸준한 노력의 결과로 자동차 수출국으로 발돋움하고 있으며 이 분야 에서으 선진국과의 경쟁이 점점 치열해질 전망이다. 이러한 세계 시장에서의 경쟁 대열에서 탈 락되지 않기 위해서는 무엇보다도 제품 품질의 향상, 원가의 절감 등이 이루어져야 할 것이며 이 에 대한 노력을 게을리 해서는 안될 것이다. 한편 이와는 별도로 좀더 다른 각도에서 자동차 공업의 방향을 고찰할 필요가 있다. 즉 미래에도 계속해서 현재의 왕복동 내연기관이 자동차 구동용으로 사용될 것인가 하는 점이다. 엔진의 성능 향상, 연비의 감소, 엄격한 배기가스 규 제에의 대처 등에 대한 연구가 활발히 진행되고 있지만 기술개발에는 한계가 있으며 제품은 점점 복잡하게 되어 결국은 제품가격 및 A/S 비용이 상승되는 역효과를 나타낼 가능성이 높다. 이에 세계적인 자동차 제조회사에서는 오래전부터 새로운 방식의 미래형 자동차 engine 개발에 착수 하였으며 계속적인 연구를 진행하고 있다. 이러한 미래형 자동차 engine의 대표적인 것으로 gas turbine engine이 있다. 가스터어빈이라 하면 우선 항공기용의 jet engine을 생각하게 된다. 그 외에 발전용으로 가스터어빈은 이용되고 있으며 근래 다시 등장한 자동차용의turbocharger 역시 가스터어빈의 한 응용분야라고 할 수 있다. turbocharger의 경우는 내연기관의 출력향상을 주 목적으로 내연기관에 부착되어 이용되고 있는 반면에 gas turbine engine은 기존의 내연기관을 대체하여 자동차 구동용으로 이용되는 점에 그 차이가 있다. 아직은 실용화되징 않았지만 미래형 자동차 기관으로서의 이용가능성이 높은 gas turbine engine을 다음에 간략히 소개하고자 한다. 생산량과 하천수에 의한 생산량과의 비는 풍건물의 경우 0.6, 매물의 경우 0.5였으며 감자의 경우는 0.2이하였다. 4. 염분용수 관개구와 하천수 관개구의 모든작물에서 풍건물 생산량과 축배량 사이에는 강한 직선적인 관계를 보였다. 보리, 감자의 작물 생산량과 축배량사이에도 선형의 관계가 성립되었으나, 밀과 옥수수의 매물 생산량과 축배량사이에는 곡선적인 관계를 나타내었다..18cm)에 필적되는 연평균 4.16cm로 나타났다. 5. 전체 시험구로부터으 연평균 토양유실량은 Sharpsburg 점질양토에 대한 S.C.S 한계허용치 10ton/ha/year 이내로 나타났다. 비처리구에서의 토양유실량은 평균 2.56ton/ha/year로 높게 나타난 반면 3개의 서로 다른 추리구인 비수구, 초생수로구 및 Bromegrass구에서는 각각 0.152, 0.192 및 0.290ton/ha/year로 낮은 결과를 가져왔다. 6. 평균 침전량에 대한 L.S.D. 검정 걸과 전시험구중 비처리구가 고도의 유의차를 나타낸 반면 비수구, 초생수로구 및 Bromegrass 목초구 간에는 아무런 유의차가 인정되지 않았다. 7. 농지보전 처리구인 배수구와 초생수로구는 비처리구에 비해 낮은 침두 유출량과 낮은 토양유실량을 나타내었다.구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.437-444
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• 2016

Rapid and reliable identification of microorganisms is important to maintain food quality and to control safety. MALDI-TOF MS-based identification methods are relatively fast and simple compared to other conventional methods including gram staining and biochemical characterization. A colony on subcultured media can be directly prepared on the analysis plate without further complex treatments. In this study, we confirmed the applicability of MALDI-TOF MS-based identification of foodborne pathogens such as Salmonella Enteritidis/Typhimurium, Staphylococcus aureus, Vibrio parahaemolyticus, Clostridium perfringens, Listeria monocytogenes, Yersinia enterocolitica, Bacillus cereus, Campylobacter jejuni, Campylobacter coli, and Cronobacter sakazakii on the Korea Food Standard Codex. MALDI-TOF MS data of the pathogenic reference strains were incorporated into a commercial MicroID (ASTA Inc.) database. Other pathogenic reference strains and seven isolates from various food samples were correctly identified to the species level by using the MicroID database. In conclusion, MALDI-TOF MS is comparable with commercial biochemical identification.

• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.460-465
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• 2018

Deep sea water is deeper than 200 m in depth and maintains cool temperatures. It is clean seawater not contaminated by E. coli and other general bacteria. Because deep sea water is a recyclable resource with high industrial value, activities for commercial use are vigorously developing. We investigated safety, quality characteristics, and mineral contents of prototype products using deep sea water as a substitute for a curing agent and compared it with existing commercially processed products. This study examined the potential of deep sea water as an alternative to curing agent solution. As a result, safety and quality characteristics of processed meat products with deep sea water were not different from commercially processed meat products, but mineral contents were higher in processed meat products with deep sea water. Deep sea water could be widely used as purity salt and purity minerals that can replace chemical substances such as chemical salts. A new, active food market using deep sea water will emerge in the near future.