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Dynamic Characteristic Analysis Procedure of Helicopter-mounted Electronic Equipment (헬기 탑재용 전자장비의 동특성 분석 절차)

  • Lee, Jong-Hak;Kwon, Byunghyun;Park, No-Cheol;Park, Young-Pil
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.8
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    • pp.759-769
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    • 2013
  • Electronic equipment has been applied to virtually every area associated with commercial, industrial, and military applications. Specifically, electronics have been incorporated into avionics components installed in aircraft. This equipment is exposed to dynamic loads such as vibration, shock, and acceleration. Especially, avionics components installed in a helicopter are subjected to simultaneous sine and random base excitations. These are denoted as sine on random vibrations according to MIL-STD-810F, Method 514.5. In the past, isolators have been applied to avionics components to reduce vibration and shock. However, an isolator applied to an avionics component installed in a helicopter can amplify the vibration magnitude, and damage the chassis, circuit card assembly, and the isolator itself via resonance at low-frequency sinusoidal vibrations. The objective of this study is to investigate the dynamic characteristics of an avionics component installed in a helicopter and the structural dynamic modification of its tray plate without an isolator using both a finite element analysis and experiments. The structure is optimized by dynamic loads that are selected by comparing the vibration, shock, and acceleration loads using vibration and shock response spectra. A finite element model(FEM) was constructed using a simplified geometry and valid element types that reflect the dynamic characteristics. The FEM was verified by an experimental modal analysis. Design parameters were extracted and selected to modify the structural dynamics using topology optimization, and design of experiments(DOE). A prototype of a modified model was constructed and its feasibility was evaluated using an FEM and a performance test.

우리나라의 모자보건사업 (여성과 어린이 건강문제와 증진방안)

  • Park Jeong-Han
    • 대한예방의학회:학술대회논문집
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    • 2002.07b
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    • pp.3-17
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    • 2002
  • 국민건강은 국가발전의 기본조건이다. 국민건강은 건강한 어린이의 출산에서 비롯되고, 건강한 어린이의 출산을 위하여 여성이 건강해야 한다 따라서 여성과 어린이 건강보호와 증진을 위한 모자보건사업은 국가보건사업 중 최우선 사업으로 추진되어야 한다. 우리나라의 모자보건사업은 1960대부터 보건소를 통하여 가족계획, 산전관리, 안전분만유도, 예방접종을 중심으로 하였다. 1980년대에 들어와 전국민의료보험의 실현과 국민생활수준의 향상 등으로 산전관리 수진율과 시설분만율이 급격히 증가하여 1990년대 후반에는 거의 100%에 도달하였고, 가족계획실천율도 1991년에 79.4%까지 증가하여 합계출산율이 1.6으로 감소하였고, 어린이 기본예방접종률도 90%이상이 되어 전염병 발생률이 현저히 감소하였다. 전통적인 모자보건사업 관련 지표들이 이렇게 향상되자 일선 보건요원에서부터 중앙정부의 정책결정권자에 이러기까지 모자보건사업에 대한 관심도가 떨어져 중앙부처의 모자보건업무 담당 부서도 축소되고, 모자보건 사업도 쇠퇴하였다. 그러나 어린이와 여성의 건강실태를 자세히 들여다보면 심각한 문제들이 대두되고 있다. 시설 분만율의 증가에 따라 제왕절개분만율이 40%대까지 급증하였고, 모유수유률은 10%대로 떨어졌다. 어린이의 체격은 커지고 있으나 체력은 떨어지고, 비만한 어린이가 급증하여 당뇨병과 같은 성인병 유병률이 어린이들에게 증가하고, 사고에 의한 어린이 사망과 장애가 늘고 있다. 또한 청소년들의 흡연율과 음주률이 증가하고, 성적 성숙이 빨라지고 사회의 개방풍조로 성(性)활동 연령이 낮아지고 성활동이 증가하여 혼전임신과 성폭력이 증가하고 있다. 여성들은 일찍 단산하고, 폐경 연령은 높아지고, 평균수명은 길어져 중년기와 장년기 그리고 노년기가 길어져 각종 만성질환에 이환될 기회가 늘어났다. 이러한 시기의 중요 건강문제들은 뇌혈관질환, 폐암, 유방암, 골다공증, 뇨실금 등과 같이 해결하기 어려운 것들이다. 이렇게 어린이와 여성들에게 새로운 건강문제들이 대두되고 있으나 이에 대한 대응정책이 없었고, 따라서 새로운 모자보건사업이 개발되지 않았으며 일선 보건요원의 훈련도 없었다. 그리고 이러한 건강실태를 파악하여 대책을 마련하고, 보건사업을 평가할 수 있는 보건정보체계가 없는 실정이다. 1990년대 중반에 소수의 학자들이 어린이와 여성건강문제의 심각성을 제기하고, 모자보건사업 활성화의 필요성을 주장하여 보건복지부가 '모자보건선도보건사업'이라는 이름으로 1999년부터 2001년까지 3년간 23개 보건소에서 시범사업을 시행하였다. 이 시범사업에서는 한정된 자원으로 여성과 어린이 보건문제를 효과적으로 해결하기 위해 새로운 보건사업의 개발과 효율적으로 수행하는 방법의 개발에 역점을 두어 많은 성과를 거두었다. 시범사업의 경험을 바탕으로 2002년에는 전국의 45개 보건소로 확대해나가고 있다. 모자보건선도보건사업에서는 임산부가 대상이었던 기존의 모자보건사업과는 달리 신생아, 영유아, 학동기 어린이, 청소년, 그리고 신혼부부에서부터 장년기 여성에 이르기까지 사업대상을 확대하고 생애주기에 따라 지역사회 건강문제해결을 목표로 한 보건사업을 수행하도록 하였다. 사업수행 과정에서 보건소는 지역내 대학과 협력체계를 구축하여 기술적 지원을 받고, 보건요원의 교육 훈련을 통해 사업기획 능력과 전문지식과 기술을 향상시켰고, 보건교육에 필요한 시설과 장비를 구입하였고, 민간의료기관과 연계하여 보건서비스의 질을 향상시켰다. 모자보건 선도보건소에서 제공하는 서비스는 취약계층 중심의 보건교육, 상담 및 지도, 고위험대상자 조기발견 및 민간기관 의뢰 및 주구관리, 질병 조기발견을 위한 검진 의뢰, 지역 보건통계 생산과 관리, 그리고 지역내 가용자원 안내 등이며, 저소득층에 대해서는 민간의료기관에 의뢰 또는 검진비용을 지원하였다. 이와 같이 지역사회 민간기관과 협력체계를 구축함에 따라 대상자를 지속적으로 관리할 수 있는 정보를 공유하게 되었고, 건강증진 및 질병예방, 치료, 사후관리를 포함한 지속적이고 포괄적인 서비스를 제공할 수 있게 되었다. 특히 고위험 및 건강의심 대상, 임부와 장년기 여성에 대해서는 건강검진서비스를 과감히 민간기관에 의뢰, 위탁하친 보건소는 상담자, 정보관리자로서의 역할로 전환할 수 있었다. 그러나 사업관리자의 양적 평가에 대한 고정관념과 질적 평가에 대한 인식부족, 기본 생정통계와 정보체계의 미비로 인한 부정확한 통계생산, 사업요원의 전문지식과 기술 부족, 그리고 인력부족 등이 문제점으로 대두되었다. 효율적인 사업확산과 조기 정착을 위해 중앙정부의 일관성 있는 정책과 재정적 지원이 필수적이며, 보건정보체계확립, 그리고 공공보건기관과 민간의료기관간의 공식적인 협력체계확립이 필요하다. 사업추진 모니터링 및 평가, 조정을 위하여 중앙에 '모자보건 선도사업 기술지원단'을 구성하여 운영하고, 프로그램 운영이 잘되는 보건소를 특성화 보건소로 지원 육성하고, 사업요원의 업무 적정화를 위한 보건소 조직과 기존 보건사업체계의 평가와 재편이 필요하다. 보건사업요원의 자질 향상을 위한 지속적인 교육 훈련 시스템과 보건통계생산 관리를 위한 정보체계의 구축이 요구된다. 모자보건사업관련 보건교육자료를 수집하고 개발하여 전국 보건소에 공급하는 중앙 보건교육자료 및 정보센터가 필요하다.

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Etiological Properties and Coat Protein Gen Analysis of Potato Virus Y Occuring in Potatoes of Korea (우리나라 감자에 발생하는 PVY의 병원학적 특성 및 외피단백질 유전자 분석)

  • ;Richard M. Bostock
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • 1995.06b
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    • pp.77-96
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    • 1995
  • To obtain basic informations for the improvement of seed potato production in Korea, some etiological properties of potato virus Y(PVY) distributed in the major seed potato production area(Daekwanryeong) were characterized, and the nucleotide and amino acid sequences of the coat protein gene of the PVY strains isolated were analyzed. PVY strains in Daekwonryeong, an alpine area, were identified to be two strains, PVYo and PVYN by symptoms of indicator plants, and their distribution in potato fields was similar. Major symptom on potato varieties by PVY was grouped as either mosaic alone or mosaic accompanied with veinal necrosis in the lower leaves. The symptom occurrence of the two symptoms was similar with Irish Cobbler, but Superior showed a higher rate of mosaic symptom than the other. The PVY strain which was isolated from potato cv. Superior showing typical mosaic symptoms produced symptoms of PVY-O on the indicator plants of Chenopodium amaranticolor, Nicotiana tabacum cv. Xanthi nc and Physalis floridana, but no symptom o Capsicum annum cv. Ace. Moreover, results from the enzyme-linked immunosorbent assay with monoclonal and polyclonal antibodies showed that the isolated PVY reacts strongly with PYV-O antibodies but does not react specifically with PVY-T antibodies. The purified virus particles were flexious with a size of 730$\times$11nm. On the basis of the above characteristics, the strain was identified to be a PVY-O and named as of PVY-K strain. The flight of vector aphids was observed in late May, however, the first occurrence of infected plants was in mid June with the bait plants surrounded with PVY-infected potato plants and early July with the bait plants surrounded with PVY-free potato plants. PVY infection rates by counting symptoms on bait plants (White Burley) were 1.1% with the field surrounded with PVY-free potato plants and 13.7% the fields surrounded with PVY-infected potato plants, showing the effect of infection pressure. The propagated PVY-K strain on tobacco(N. sylvestris) was purified, and the RNA of the virus was extracted by the method of phenol extraction. The size of PVY-K RNA was measured to be 9, 500 nucleotides on agarose gel electrophoresis. The double-stranded cDNAs of PVY-K coat protein(CP) gene derived by the method of polymerase chain reaction were transformed into the competent cells of E. coli JM 109, and 2 clones(pYK6 and pYK17) among 11 clones were confirmed to contain the full-length cDNA. Purified plasmids from pYK17 were cut with Sph I and Xba I were deleted with exonuclease III and were used for sequencing analysis. The PVY-K CP gene was comprised of 801 nucleotides when counted from the clevage site of CAG(Gln)-GCA(Ala) to the stop codon of TGA and encoded 267 amino acids. The molecular weight of the encoded polypeptides was calculated to be 34, 630 daltons. The base composition of the CP gene was 33.3% of adenine, 25.2% of guanine, 20.1% of cytosine and 21.4% of uracil. The polypeptide encoded by PVY-K CP gene was comprised of 22 alanines, 20 threonines, 19 glutamic acids and 18 glycines in order. The homology of nucleotide sequence of PVY-K CP gene with those of PVY-O(Japan), PVY-T(Japan), PVY-TH(Japan), PVYN(the Netherlands), and PVYN(France) was represented as 97.3%, 88.9%, 89.3%, 89.6% and 98.5%, respectively. The amino acid sequence homology of the polypeptide encoded by PVY-K CP gene with those encoded by viruses was represented as 97.4%, 92.5%, 92.9%, 92.9%, and 98.5%, respectively.

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An Analysis on the Understanding of High School Students about the Concept of a Differential Coefficient Based on Integrated Understanding (통합적 이해의 관점에서 본 고등학교 학생들의 미분계수 개념 이해 분석)

  • Lee, Hyun Ju;Ryu, Jung Hyeon;Cho, Wan Young
    • Communications of Mathematical Education
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    • v.29 no.1
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    • pp.131-155
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    • 2015
  • The purpose of this study is to investigate if top-ranked high school students do integrated understanding about the concept of a differential coefficient. For here, the meaning of integrated understanding about the concept of a differential coefficient is whether students understand tangent and velocity problems, which are occurrence contexts of a differential coefficient, by connecting with the concept of a differential coefficient and organically understand the concept, algebraic and geometrical expression of a differential coefficient and applied situations about a differential coefficient. For this, 38 top-ranked high school students, who are attending S high school, located in Cheongju, were selected as subjects of this analysis. The test was developed with high-school math II textbooks and various other books and revised and supplemented by practising teachers and experts. It is composed of 11 questions. Question 1 and 2-(1) are about the connection between the concept of a differential coefficient and algebraic and geometrical expression, question 2-(2) and 4 are about the connection between occurrence context of the concept and the concept itself, question 3 and 10 are about the connection between the expression with algebra and geometry. Question 5 to 9 are about applied situations. Question 6 is about the connection between the concept and application of a differential coefficient, question 8 is about the connection between application of a differential coefficient and expression with algebra, question 5 and 7 are about the connection between application of a differential coefficient, used besides math, and expression with geometry and question 9 is about the connection between application of a differential coefficient, used within math, and expression with geometry. The research shows the high rate of students, who organizationally understand the concept of a differential coefficient and algebraic and geometrical expression. However, for other connections, the rates of students are nearly half of it or lower than half.

The Relationship between attribution styles and attitude toward mathematics of mathematically gifted students and those of regular students at elementary schools (초등학교 수학영재와 일반학생의 귀인성향과 수학에 대한 태도와의 관계)

  • Lim, Seong-Hwan;Whang, Woo-Hyung
    • Communications of Mathematical Education
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    • v.24 no.2
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    • pp.415-444
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    • 2010
  • The purpose of this study is to provide information that will help understand unique characteristics of mathematically gifted students and that can be utilized for special programs for mathematically gifted students, by investigating difference and relationship between attribution styles and attitude toward mathematics of mathematically gifted students and those of regular students. For that purpose, 202 mathematically gifted students and 415 regular students in 5th and 6th grades at elementary schools were surveyed in terms of attribution styles and attitude toward mathematics, and the result of the study is as follows. First, as for attribution styles, there was no difference between gifted students and regular students in terms of grade and gender, but there was significant difference in sub factors because of giftedness. Second, there was not significant difference between grades. but there was significant difference in sub factors between genders. Mathematically gifted students were more positive than regular students in every sub factor excepting gender role conformity, and especially they showed higher confidence and motivation. Third, according to the result of correlation analysis, there was significant static correlation between inner tendencies and attitude toward mathematics with both groups. The gifted group showed higher correlation between attribution of effort and attitude toward mathematics and inner tendencies and confidence than the regular group. The gifted group showed higher correlation in sub factors, and especially there was high static correlation between attribution of talent and confidence, and attribution of effort and motivation. Fourth, according to the result of multiple regression analysis, inner tendencies showed significant relation to attitude toward mathematics with both groups, and especially the influence of attribution of effort was high. Both attribution of effort and attribution of talent were higher in the gifted group than the regular group, and attribution of effort had a major influence on practicality and attribution of talent had a major influence on confidence.

국제 수학 올림피아드 참가 후보자들을 위한 상황대처훈련에 관한연구

  • 김보경;조성희;이군현
    • Proceedings of the Korean Society for the Gifted Conference
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    • 1994.08a
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    • pp.1.2-37
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    • 1994
  • Currently Korea encourages gifted high schoolers and junior high schoolers to participate in international achievement contests such as International Olympiads. Participants for these contests are selected nationwide among gifted students in areas of mathematics, physics, chemistry, and others. They go through a series of screening tests and programs. One of the screening processes IS Korean Olympiad School, which provides study programs each summer for student-candidates prior to following year's International Olympiads. Approximately 40 students of high schools and junior high schools, in each subject of study, gather at Korean Olympiad Summer School, and they go through intensive study programs during a short period of time. Out of 40 candidates,' less than 10 students are finally selected to participate in International Olympiads. In this study, a psycho-educational program called "Situation Coping Training Program" was developed to enhance ahievement motivation for these student-candidates. This study was to see if this training program actually improved their cognitive, emotive motivation factors, and to see how this training program affected their achievement level. Training was administered for five days. This training program was found effective for participants to increase self-efficacy, internal locus of control, and anxiety copmg. These cognitive and emotive motivation factors, other than intelligence, were found to have positive relationship with achievement level, of which self-efficacy and attribution style of students were found as two best predictors of achievement. This training program was perceived as necessary. by participants, and helpful for recovering self-confidence and self-control as well as coping pressure. Suggestions were made that this kind of training program be administered as a regular curriculum in preparative study programs such as Korean Olympiads, since cognitive, emotive motivation factors are related with achievement, and furthermore, be utilized in all gifted education programs in Korea. in Korea.

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도체 현수방법에 따른 쇠고기 품질 비교

  • Park, Beom-Yeong;O, Mi-Ra;Kim, Jin-Hyeong;Jo, Su-Hyeon;Ha, Gyeong-Hui;Seong, Pil-Nam;Hwang, In-Ho;Lee, Jong-Mun;Kim, Dong-Hun;An, Jong-Nam
    • Proceedings of the Korean Society for Food Science of Animal Resources Conference
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    • 2006.05a
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    • pp.146-150
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    • 2006
  • 도축 후 2일째 가열 감량은 시험구(골반골 현수)가 대조구(아킬레스건 현수)에 비하여 유의적으로 감량이 높았으나, 드립량에 있어서는 반대의 결과를 보였으며, 전체 감량은 두 처리구간 차이가 없었다. 연도의 지표인 전단력가는 대조구 $6.45kg/cm^2$로 시험구 $5.52kg/cm^2$에 비하여 유의적으로 높았으며, 골반골 현수를 통하여 도축 후 8일차의 대조구의 전단력 수준을 보여 숙성기간을 약 1주일 정도 단축이 가능하였다. 근절길이는 대조구 $1.93{\mu}m$, 시험구 $2.48{\mu}m$로 시험구가 유의적으로 길어 골반골 현수에 의한 단축 억제 효과로 볼 수 있다. 관능 평가 결과 도축후 2일차에는 대조구에 비하여 시험구가 다즙성, 연도, 향미, 기호성에서 유의적으로 높은 값을 보였으나, 도축 후 8일째에는 대조구와 시험구간에 차이를 보이지 않았다. 출하 연령과 현수방법에 따른 대퇴이두근의 물리적 특성을 비교한 결과로서 근절길이는 모든 월령에서 시험구가 대조구에 비하여 길었다. 전단력은 시험구가 대조구에 비하여 유의적으로 낮은 결과를 보였다. 골반골 현수에 의한 전단력가 감소 효과는 출하 월령이 많을수록 효과가 큰 것으로 나타났다. 드립 발생율은 대조구가 시험구에 비하여 유의적으로 높은 경향을 보였다. 가열 감량과 보수성은 처리구에 관계없이 유의적인 차이를 보이지 않았다. 관능 특성을 비교한 결과 30개월 미만의 경우에는 유의적인 차이를 보이지 않았으나, 30개월 이상에서는 처리구가 대조구에 비하여 다즙성 연도, 향미, 기호성 모두 우수한 것으로 나타났다. 특히 골반골 현수는 출하 월령이 증가됨에 따라 관능 특성의 개선율이 높은 것으로 나타났다. 수 있다.분별을 성공적으로 수행하였다.(p<0.05), 맛, 연도, 다즙성 및 전체적인 기호성은 유의한 차이가 없었다.자체를 악하다고 볼 수 없고 더구나 구원을 이 세상에서의 이탈로 볼 수 없다. 진정한 구원이란 원래 하나님이 보시기에 아름다웠던 그 세상으로의 회복을 포함한다. 이런 면에서 하나님 주권 신앙 하에서 구원이란 전 인격적인 구원, 전 우주적인 구원이 된다. 그렇기 때문에 성도는 세상의 삶과 학문, 예술, 정치, 경제, 사회를 포함한 모든 분야를 하나님의 뜻 가운데서 그 원래의 목적에 부합할 수 있도록 회복시키는 일에 적극 참여해야 한다.자체가 이를 주도하기는 사실 어려움이 있다. 그리고 대형유통점이 영업행위를 영업시간제한에서부터 출점제한에 이르기까지 규제하는 건은 심사숙고하여야 한다. 대형유통점이 국가경제 및 지역사회에 미치는 영향이 부정적인가 긍정적인가에 대해 국내외 학계와 업계에서 여전히 많은 논란이 있기 때문이다. 정부와 지자체에 의한 시장개입은 반드시 필요한 경우에 한해 합당한 방법에 의해 이루어져야 한다. 대형유통점에 대한 규제는 지역사회에 미치는 영향을 다면적으로 평가한 결과에 근거하여 이루어져야 할 것이다. 대부분의 지자체는 체계적인 평가시스템과 객관적인 통계 자료를 갖고 있지 못한 실정이다. 향후 가장 시급한 과제는 시장개방 이후 지난 10년간 대형유통점이 지역사회에 미친 영향에 관한 광범위한 통계자료를 수집하고 이를 체계적으로 분석하여 정책방향을 올바르게 설정하는 것이라 할 수 있다.i와 K. pneumoniae가 존재하며 확산 중임을 시사한다. 앞으로 CTX-M형 ESBL의 만연과 변종 CTX-M형 ESBL의 출연을 감시하기 위한 정기적인 연구와 조사가 필요한 것으로 생각한다., A2-1, B1-1, B2-1의 경우,

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돼지고기가 생체내(生體內) 중금속(重金屬)의 축적억제(蓄積抑制)에 미치는 영향

  • Han, Chan-Gyu;Lee, Nam-Hyeong;No, Jeong-Hae;Seong, Gi-Seung;Chae, Chan-Hui
    • Proceedings of the Korean Society for Food Science of Animal Resources Conference
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    • 1999.06a
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    • pp.97-117
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    • 1999
  • This study was performed to investigate the effect of pork on the cadmium detoxification in rats. Ninety male Sprague-Dawley rats weighing $125.3{\pm}1.4g$ were divided into five groups based on cadmium treatment(0, 25, 50, 100, 250ppm) and five levels of Cd in AIN-76 purified diet had been fed for 8 weeks. Cadmium was supplemented with a form of $CdCl_2$.. During following 8 weeks of intoxication, casein was replaced by pork and the effect of pork on cadmium- detoxification was compared with casein. After 8 weeks of Cd intake had resulted in apparent cadmium intoxication; reduced growth rate, enlarged kidney and testis, decreased hematocrit value and hemoglobin content in response to the supplemented Cd levels in the diets. Discontinuing cadmium feeding, the body weights were relieved. Pork-fed groups seemed to have higher body weight than casein-fed groups. Hemoglobin content and hematocrit value became normal range at detoxification stage. The weights of liver, kidney, and testis were decreased along with cadmium intake. However, organ weight ratio was not affected by cadmium. Cadmium accumulation in liver and kidney showed a tendency to increase in the cadmium-exposed groups. The levels of metallothionein were also significantly elevated in the tissues of liver in response to the levels of Cd supplemented(p<0.05). Cadmium concentration in kidney was two times higher than that in liver. Cadmium removal rate of liver was higher than that of kidney. Cadmium accumulation of the pork-fed group was lower than that of casein. Especially, the factors which affected the cadmium contents in kidney were $Cd^{***}$ and $Cd{\times}pork^{***}$. Metallothionein(MT) was increased with cadmium, and MT was not likely to be affected by pork. Based on the findings from gross lesion, rats fed 250ppm of Cd were externally emaciated, had exposed penis and observed atrophies of kidney and testis. Histopathological observation seemed that the liver of groups feeding Cd supplemented diets showed cellular degeneration and accumulation of eosinophilic materials in the capillaries. In kidney, rats fed Cd diets had shown tubular epithelium degeneration and lesions of basophilic materials, while testis were weakened in numbers of spermatid and sporadically enlarged of giant cells. But the rats administered cadmium-detoxified diet supplemented pork for 7 weeks were shown individually decreased lesions compared with the rats supplied with casein diet.

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Application of an empirical method to improve radar rainfall estimation using cross governmental dual-pol. radars (범부처 이중편파레이더의 강우 추정 향상을 위한 경험적 방법의 적용)

  • Yoon, Jungsoo;Suk, Mi-Kyung;Nam, Kyung-Yeub;Park, Jong-Sook
    • Journal of Korea Water Resources Association
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    • v.49 no.7
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    • pp.625-634
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    • 2016
  • Three leading agencies under different ministries - Korea Meteorological Administration (KMA) in the ministry of Environment, Han river control office in the Ministry of Land, Infrastructure and Transport (MOLIT) and Weather Group of ROK Air Force in the Ministry of National Defense (MND) - have been operated radars in the purpose of observing weather, hydrology and military operational weather in Korea. Eight S-band dual-pol. radars have been newly installed or replaced by these ministries over different places by 2015. However each ministry has different aims of operating radars, observation strategies, data processing algorithms, etc. Due to the differences, there is a wide level of accuracy on observed radar data as well as the composite images made of the cross governmental radar measurement. Gaining fairly high level of accuracy on radar data obtained by different agencies has been shared as a great concern by the ministries. Thus, "an agreement of harmonizing weather and hydrological radar products" was made by the three ministries in 2010. Particularly, this is very important to produce better rainfall estimation using the cross governmental radar measurement. Weather Radar Center(WRC) in KMA has been developed an empirical method using measurements observed by Yongin testbed radar. This study is aiming to examine the efficiency of the empirical method to improve the accuracies of radar rainfalls estimated from cross governmental dual-pol. radar measurements. As a result, the radar rainfalls of three radars (Baengnyeongdo, Biseulsan, and, Sobaeksan Radar) were shown improvement in accuracy (1-NE) up to 70% using data from May to October in 2015. Also, the range of the accuracies in radar rainfall estimation, which were from 30% to 60% before adjusting polarimetric variables, were decreased from 65% to 70% after adjusting polarimetric variables.

Estimation of river discharge using satellite-derived flow signals and artificial neural network model: application to imjin river (Satellite-derived flow 시그널 및 인공신경망 모형을 활용한 임진강 유역 유출량 산정)

  • Li, Li;Kim, Hyunglok;Jun, Kyungsoo;Choi, Minha
    • Journal of Korea Water Resources Association
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    • v.49 no.7
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    • pp.589-597
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    • 2016
  • In this study, we investigated the use of satellite-derived flow (SDF) signals and a data-based model for the estimation of outflow for the river reach where in situ measurements are either completely unavailable or are difficult to access for hydraulic and hydrology analysis such as the upper basin of Imjin River. It has been demonstrated by many studies that the SDF signals can be used as the river width estimates and the correlation between SDF signals and river width is related to the shape of cross sections. To extract the nonlinear relationship between SDF signals and river outflow, Artificial Neural Network (ANN) model with SDF signals as its inputs were applied for the computation of flow discharge at Imjin Bridge located in Imjin River. 15 pixels were considered to extract SDF signals and Partial Mutual Information (PMI) algorithm was applied to identify the most relevant input variables among 150 candidate SDF signals (including 0~10 day lagged observations). The estimated discharges by ANN model were compared with the measured ones at Imjin Bridge gauging station and correlation coefficients of the training and validation were 0.86 and 0.72, respectively. It was found that if the 1 day previous discharge at Imjin bridge is considered as an input variable for ANN model, the correlation coefficients were improved to 0.90 and 0.83, respectively. Based on the results in this study, SDF signals along with some local measured data can play an useful role in river flow estimation and especially in flood forecasting for data-scarce regions as it can simulate the peak discharge and peak time of flood events with satisfactory accuracy.