• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.735-741
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• 2016

Increasing the total length of waveguide-below-cutoff array(WBCA) as it is used to the duct in order to enhance shielding effectiveness, the design could cause higher cost, higher levels of difficulties in construction and the interruption a flow velocity. The multi-layered WBCA can compensate for this problem, which can be designed by crossing each waveguide layer. By conducting simulations from 2-layer to 8-layer structure, it can be observed that the shielding effectiveness increases from 52 dB to 75 dB. Comparing with the original WBCA in a shape of mono layer rectangular, our proposed waveguide becomes similar with the original value as the number of crossing layer increases. In addition, the analysis with the flow of fluid in the duct installed multi-layered WBCA are required. We demonstrate this analysis by doing the flow of fluid simulation, and concluded that the multi-layered WBCA has loss of flow of fluid less than unit rectangular WBCA.

• Communications of Mathematical Education
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• v.12
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• pp.463-477
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• 2001

국가의 국가경쟁력은 학창시절 학생의 학력만큼 중요하다. 성인의 경우, 학력을 위한 노하우는 체험을 통해 터득할 수 있었다. 그러나 국가경쟁력에 관해서는 우물 안 내부관점을 벗어나기 힘들어 추진 방향과 제도 운영에 자칫 시행착오를 범하기 쉽다. 이는 사안에 대해 본질적인 접근보다 껍데기만을 쫓기 때문이었다. 이 현상을 분석하려면 관점과 보이지 않는 영역의 것들을 다룰 수 있는 수학적 사고법이 필요하며, 이 능력은 현 지식정보화 사회에서 매우 긴요하다. 그러나 현실은 여러 가지 이유로 수학적 사고법을 비롯한 기초학문을 위기로 몰아가고 있고, 안타깝지만 그 중심에 수학교육이 자리잡고 있다. 수학교육의 위기를 유발하는 요인으로 제도 운영에 관한 건이 있다. 제도 운영에서 한 변수의 변화, 예로 대입의 계열교차지원 허용 건, 교원임용고시에서 교과교육학 영역의 출제 건과 복수전공, 부전공 자격소지자에 대한 가산점 부여 건은 수학교육과 교육과정에 직, 간접적으로 영향을 미친다. 이 관계를 사범대학 수학교육과 현장의 사례를 통하여 조명하고, 그 문제점을 지적하고자 한다. 현 사범교육은 졸업이수학점 140학점 체제하에서 제 7차 교육과정에 따른 복수전공, 부전공 우대 정책을 펴고 있다. 수학교육과의 경우, 부전공 열풍이 불어 전공선택 과목이 3학년 1학기부터 폐강될 위기에 처해 있다. 교양교육의 고사 또는 전광교육이 예전보다 반으로 줄어들게 된 사범대학 실상에 비애감을 느끼게 된다. 이는 전문화된 교사 양성, 나아가 미래 국가경쟁력 향상에 심각한 저해 요소로 작용할 것이다. 복잡다단한 세상에서 최적화를 향한 개선 노력이 멈춰서는 안 된다. 현행 교원임용고시 운영상의 문제점을 공론화하고, 수학교육인의 중지를 모아야 할 긴박한 시점이다. 이를 계기로 교원임용고시의 운영개선과 수학교육과 교육과정을 한층 더 견실하게 하는 데에 이바지하고자 한다. 것이라면 후속연구로 이러한 가능성을 실험연구로 검증하고자 한다.toceros resting spores/Chaetoceroe vegetative cells도 80 cm 보다 상층에서는 높게 나타나 규조온도지수 분포와도 일치하는 경향을 보인다. 이상의 규조군집 분석 결과에 의하면, 홀로세의 후빙기동안 본 연구 지역인 동해 북동부에는 대마 난류의 유입이후 현재와 유사한 환경이 우세하게 발달했으나, 난류종 P. doliolus의 변화는 동해내에서 대마난류의 세기가 반복되었음을 지시하고 있다./3 수준으로 높다. 결론적으로 풍부한 화학물질들을 함유한 제주해류는 남해 및 동해의 생지화학적 과정들에 있어 상당히 중요함을 시사한다.다. 수조 상층수 중 Cu, Cd, As 농도는 모든 FW, SW수조에서 시간이 지남에 따라 일관성 있게 감소하였고, 제거속도는 Cu가 다른 원소에 비해 빨랐다. 제거속도는 FW 3개 수조 중 FW5&6에서 세 원소 모두 가장 느렸고, SW 3개 수조 중에서는 SW1&2에서 가장 빨랐다. SW와 FW간 제거속도 차이는 세 원소 모두 명확치 않았다 Cr은 FW에서 전반적으로 감소하는 경향을 보였지만 SW에서는 실험 초기에 감소하다 24시간 이후에는 증가 후 일정한 양상을 보였다. Pb은 FW에서 전반적으로 감소했지만 SW에서는 초기에 급격히 증가 후 다시 급격히 감소하는 양상을 보였다 Pb 또한 Cu, Cd, As와 마찬가지로 SW1&2에서 제거속도가 가장 빠르게 나타났다. FW 상층수 중 Hg는 시간에 따라 급격히 감소했고, 제거속도는 Fw5&6에서 가장 느렸다. 이러한 결과에 근거할 때 벼가 자라고 있고 이분해성 유기물이 풍부한 FW1&2, FW3&4 토양과 상층수에서는 유기물의 분해 활동이 활발하였지만, 벼가 경작되지 않는 FW5&6과 SW 에서는 유기물이 상대적으로 결핍되어 유기물의 분해활동이 적었을 것으로 판단된다

• Journal of Animal Environmental Science
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• v.1 no.2
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• pp.125-136
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• 1995

To use the earth heat for the pig housing, an underground heat exchanger has constructed in depth of 2.5m and 20m length. The temperature of the outlet air was max. 8 kelvin higher than that of inlet air in winter season. In spite of the -7$^{\circ}C$ outside temperature, it could keep the air temperature from the earth tube above zero degree. The heating performance was maximum in value of 3.25Wh/㎥ and average of 1.75Wh/㎥ by the airflow volume of 340㎥/h. The slope of relative humidity from outlet air has shown gentler than that of inlet air. By using the underground heat exchanger, it would be possible to prepare an relatively uniform relative humidity in the swine stalls. The temperatures on the earth, where PVC pipes are buried, have shown 10~12$^{\circ}C$ on March. This can reduce the difference between day and night temperature during this season by using the underground heat exchanger.

• Journal of Life Science
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• v.18 no.11
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• pp.1493-1498
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• 2008

We defined factors affecting the postoperative outcome in adult cardiac surgery with cardiopulmonary bypass (CPB). Thirty-two adult patients scheduled for elective cardiac surgery participated in this study. Levels of leukocyte, glutamic oxaloacetic transaminase (GOT), troponin-I (cTNI), interleukin-6 (IL-6), D-dimer and neuron-specific enolase (NSE) were significantly elevated, whereas platelet count declined in cardiac surgery with CPB. GOT and D-dimer levels at CPB-off each had a positive significant correlation significantly with 24 hrs-bleeding, total bleeding, mechanical ventilatory assist time, ICU stay time and length of hospitalization. BUN levels at CPB-off were directly related to total bleeding, mechanical ventilatory assist time, ICU stay time and length of hospitalization. Platelet count at CPB-off was inversely related to mechanical ventilatory assist time, ICU stay time and length of hospitalization. Creatinine concentration at CPB-off interrelated positively with mechanical ventilatory assist time and ICU stay time. NSE levels at CPB-off had a positive relationship with postoperative 24 hrs-bleeding. The length of hospitalization was prolonged proportionally to the elevation of cTNI levels in cardiac surgery. Aortic cross-clamping and total CPB times also related with increase of 24 hrs and total bleeding volumes and the length of hospitalization. IL-6 and ET-1 had no mutual relation with any postoperative outcome. These data suggest that GOT, BUN, creatinine, D-dimer and platelet levels are the most important factors affecting postoperative outcomes and patient's recovery in adult cardiac surgery with CPB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.77-82
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• 2012

To share the lanes with conventional vehicles, traffic operation strategy is needed for NEV (Neighborhood Electric Vehicle). Because NEV cannot accelerate sharply as fast as common car include gasoline, diesel and LPG cars, they may interrupt traffic conditions and make traffic delay. After green lights turn on, all vehicles run through the street including NEV, but NEV have a maximum speed which is 50km/h. It can be an obstacle for following vehicles and will make traffic delay of the intersection. In this reason, we need to organize traffic systems like queue jump with priority traffic signal. To analyze the necessity for NEV road operations, we simulate three scenarios in congested and non-congested conditions. First is that we examine the condition which is mixed NEV and cars on the road, the second one is that we set up lane only NEV can accepted in simulation and last one is making queue jump lane and providing priority signal for NEV. In conclusion, we can conclude that making lane only for NEV is effective to improve travel speed when rate of NEVs is over 20%. Also queue jump lane and priority signal cannot make good effect to intersection delay and average speed.

• Journal of agricultural medicine and community health
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• v.40 no.4
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• pp.240-249
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• 2015

Objectives: Farmers are known to be exposed to a variety of allergens related to the work environment. This study was conducted to determine the sensitization rates as well as South Korea that they are sensitized to certain allergens farmers through the skin prick test. Methods: By targeting a total of 1143 people living in the rural town of Gyeonggi Province, it was conducted a questionnaire containing demographic and occupational risk factors and underwent skin prick tests with 15 types of allergens(including positive and negative controls). Multivariable logistic regression analysis was used to analyze the association between occupational risk factors and skin prick test positivity. Results: Except for the 30 people whose result is invalid, positive rate of the skin prick test was 18.6% in 1,113 people. The species of house dust mite, Dermatophagoides pteronyssinus and Dermatophagoides farinae was the highest at 8.7% and 8.6%. After adjusted by age, gender, smoking and education level, odds ratio of flower plant farmers is 4.467(95% CI: 2.094-9.527) and fruit farmer is 2.275(95% CI: 1.096-4.721). In addition, the rate of sensitization to grass pollen mixture of the flower plant farmers is significantly higher(15.9%, p<0.001) than other allergens. Conclusions: Even farmers, the rate of sensitization to allergens related to the general environment, such as house dust mite is relatively dominant. However, given the presence of potential cross-reactivity between the allergens or distribution showed that the unique aspects of allergen sensitization in the flower growers, occupational cause is not be completely ruled out.

• Journal of dental hygiene science
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• v.15 no.4
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• pp.472-479
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• 2015

The purpose of this study is to examine musculoskeletal disorders and grasp the relationship between working environment factors and stress and musculoskeletal disorders in dental hygienists. The self-administered questionnaire survey was conducted with 483 dental hygienists working in Gwangju who were selected by convenience sampling. Frequency analysis, crosstab analysis, t-test, and multiple logistic regression analysis were made. Subjects' musculoskeletal disorders that complain of severe pains were 29.8%. The relationship between working environment factors and stress and musculoskeletal disorders were examined. As a result, work break frequency of working environment factors and stress were found to influence musculoskeletal disorders. For working environment factors, the odds ratio of musculoskeletal disorders of the two breaks group was 0.29 (95% confidence interval [CI], 0.11~0.73), compared with the no break group, indicating less musculoskeletal disorders. However, no significant difference was found in one break and more than three breaks groups. The odds ratio of musculoskeletal disorders of stress was 0.44 (95% CI, 0.27~0.70), indicating negative correlation. As break frequency was moderate (two breaks), musculoskeletal disorders became decreased. Stress showed negative correlation with musculoskeletal disorders.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.635-642
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• 2020

The purpose of this study was to analysis the effects of shielding area of field configuration with changing of sensitivity and density on tube current (milliampere-seconds, mAs) and image quality in automatic exposure control (AEC) system. The equipment used a digital radiography device (Digital Diagnost, Philips, Netherlands), which has a integral type with an X-ray tube and an indirect digital detector. The AEC system conditions were consisted of 9 setting environments, that mode changing of the sensitivity (S200, S400, S800) and the density (+2.5, 0, -2.5). The tube current evaluated automatically exposed mAs under 81 combination conditions crossed by AEC conditions in fixed at 40 kVp. The image quality evaluated the radiographic images that selected valid images by visual assessment the radiographic images of the self-produced conical pyramid phantom and then measured their signal to noise ratio (SNR). As a result, the maximum tube current was 60.0 mAs that automatically exposed conditions were the 100% of shielding area and the sensitivity of S200 and the density of +2.5. The minimum tube current was 0.9 mAs with non-shielding area and the sensitivity of S800 and the density of -2.5. When the shielded area 0% with the sensitivity of S200 and the density of +2.5, the maximum SNR was the highest as 25.2. But when the shielded area 25% with the sensitivity of S800 and the density of -2.5, the minimum SNR was the lowest as 4.7.

• Journal of Food Hygiene and Safety
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• v.19 no.2
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• pp.66-73
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• 2004

This study was performed to assess the microbiological quality of kimbap (rice balls rolled in laver) prepared in two conditions (normal condition or clean, sanitized condition) and to support a practical application to identify critical control points (CCPs) in the preparation and cooking processes of kimbap. Kimbap, raw materials of kimbap, utensils (knives, cutting board, and kimbal which is made of bamboo), and hands of food handlers were examined microbiologically. Airborne microbes in the kitchens were also evaluated. Escherichia coli, Salmonella and Staphylococcus aureus were not detected in all samples. The aerobic bacteria and coliform bacteria levels of all samples in clean, sanitized condition were much lower than those in normal condition. More aerobic bacteria and coliform bacteria were counted in unheated raw materials of kimbap than in heated raw materials. In both conditions, the levels of airborne microbes of the kitchens were satisfactory. The aerobic bacteria and coliform bacteria of kimbap prepared in clean, sanitized condition were one hundredth levels of those of kimbap prepared in normal condition. However, fecal coliforms were detected even in the kimbap prepared in clean, sanitized condition. The results indicate that microbiological contamination of kimbap may be mainly originated from the contaminated unheated raw materials, utensils, and hands of food handlers, and also possible cross-contamination during preparation. The CCPs for kimbap preparation and cooking were handling of unheated raw materials, cleaning and sanitizing utensils, and hand washing of food handlers.

• Korean journal of food and cookery science
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• v.28 no.1
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• pp.17-24
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• 2012

The present study was performed to expand the application of mechanically impacting technology reported in our previous studies. Several parameters were analyzed to research Korean indigenous pigmented rice. The proximate composition of Korean indigenous rice was the following; 12.0-13.4% moisture, 74.1-77.3% carbohydrate, 6.8-8.7% crude protein, 1.68-3.25% crude lipid, 0.78-1.38% crude ash, with a 6.6-7.07 pH value. The phenolic compound content of red rice was twice that of black rice. Moreover, antioxidative activity was estimated by DPPH radical-scavenging activity (IC50 = 0.15-1.04 mg/mL). Anthocyanin and chlorophyll in each pigmented rice type were detected by spectrophotometer. Garaedduk samples were prepared with non-waxy rice, salt, 24% water, and/or 15% indigenous pigmented rice(red, green and black, w/w of total swelling non-waxy rice) and adapted with or without mechanically impacting technology. Hardness, as a main texture profile parameter of Garaedduk was maintained up to 3 days under storage at $20^{\circ}C$. The results suggest that Korean indigenous pigmented rice can be applied for functional Garaedduk adapted with mechanically impacting technology.