• 제목/요약/키워드: Class C

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학습구조차트를 활용하는 등산학습법의 초등수학 적용과 효과에 관한 연구 (The Effects of 'Climbing learning Method' in the Learning of Mathematics in Elementary School)

  • 백민호;김판수
    • 한국초등수학교육학회지
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    • 제11권2호
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    • pp.177-197
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    • 2007
  • 본 연구에서는 Saito Noboru(재등 승(齋藤 昇)) 교수에 의해 실천 연구되었던 등산학습법 - 학습 요소 사이의 관계 및 전체 학습 내용의 체계적, 구조적 관계를 파악할 수 있도록 학습구조차트를 활용한 학습 방법 - 을 초등학교 저학년과 고학년 학생들에게 적용하는 실험 수업을 통해, 등산학습법이 학습자의 수학 학습에 미치는 영향을 살펴보고자 하였다.

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광주지역 결혼이주여성의 식품 및 영양소 섭취 실태 (Food intake and nutritional status of female marriage immigrants residing in Gwangju, Korea)

  • 양은주;길진모
    • Journal of Nutrition and Health
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    • 제49권5호
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    • pp.358-366
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    • 2016
  • 본 연구는 광주지역에 거주하는 결혼이주여성 83명을 대상으로 일반적 특성, 신체 계측 및 혈압측정, 식품 및 영양소 섭취량을 조사하여 결혼이주 여성의 영양섭취상태 및 건강 관련 요인을 파악하기 위해 수행되었다. 연구대상자의 평균연령은 31세였으며 한국 평균거주기간은 5.3년이었고 연령 분포는 20~29세가 40명 (48.2%), 30~49세가 43명 (51.8%) 이었다. 조사대상자의 평균체중은 53.7 kg, 평균 신장은 156.3 cm 였으며, 거주기간이 5년 이상인 그룹이 5년 미만인 그룹에 비해 체중, BMI, 체지방률, 이완기 혈압 등이 유의적으로 높았다. 24시간 회상법을 통해 식품군 섭취량을 분석한 결과 20~29세 그룹에 비해 30~49세 그룹의 채소류 섭취량이 유의적으로 높았으나, 국민건강영양조사에 의한 같은 연령대의 우리나라 여성과 비교하면 과일류, 육류, 당류 섭취량이 낮고 계란류, 어패류, 우유 및 유제품류의 섭취량이 높은 편이었다. 영양소 섭취상태를 살펴보면 총 에너지섭취량은 1,641.0 kcal였으며 20대 조사대상자의 85.0%가 에너지필요 추정량 이하로 에너지를 섭취하였으며, 30~40대의 76.7%가 에너지필요추정량 이하로 섭취하였고, 칼슘, 아연, 비타민 A, 비타민 $B_6$, 비타민 C, 엽산 등은 조사대상자의 50% 이상이 평균필요량 미만으로 섭취하였다. 20대 그룹에 비해 30~40대 그룹이 비만한 경향을 나타냈으나 식품섭취량에 차이가 없었으며, 오히려 채소 섭취량이 유의적으로 많았으며 식생활과의 관련성이 적었다. 조사대상자를 거주기간으로 구분하여 비교하면 거주기간이 5년 이하인 그룹이 5년 이상 거주 그룹에 비해 콜레스테롤의 섭취량이 유의적으로 높았으며, 콜레스테롤 섭취량이 계란이나 우유와 상관관계가 있는 것으로 조사되었다. 본 연구대상자의 평균 연령은 30세로 비교적 젊고 건강하여 한국 이주 후의 식생활 변화에 의한 건강상의 변화에 큰 영향이 나타나지는 않은 것으로 생각된다. 우리나라 결혼이주여성의 영양섭취상태는 사회 경제적 여건 등과 같은 다양한 요인에 의해 영향을 받기 때문에 결혼이주 여성의 올바른 식생활 정착 및 다양하고 경제적이며 건강한 식품선택을 위한 교육이 필요함을 알 수 있었다. 특히 결혼 이주 여성의 식생활에 영향을 미치는 다양한 요인에 대응할 수 있는 맞춤형 교육이 필요하며, 인터넷 등의 교육매체를 적극 활용해야 될 것으로 생각된다. 주부의 건강한 식품선택과 올바른 영양관리는 가족전체의 식품섭취와 영양상태에 직접 영향을 미치며 건강한 사회의 초석이 되므로 결혼이주여성에 대한 장기적이고 적극적인 영양교육이 필요하다.

국가의 해양주권 수호를 위한 한국해군의 전력건설 방향 (The Construction Direction of the ROK NAVY for the Protection of Marine Sovereignty)

  • 신인균
    • Strategy21
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    • 통권30호
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    • pp.99-142
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    • 2012
  • Withe increased North Korea's security threats, the South Korean navy has been faced with deteriorating security environment. While North Korea has increased asymmetric forces in the maritime and underwater with the development of nuclear weapons, and China and Japan have made a large investment in the buildup of naval forces, the power of the Pacific fleet of the US, a key ally is expected to be weakened. The biggest threat comes from China's intervention in case of full-scale war with North Korea, but low-density conflict issues are also serious problems. North Korea has violated the Armistice Agreement 2,660 times since the end of Korean War, among which the number of marine provocations reaches 1,430 times, and the tension over the NLL issue has been intensifying. With tension mounting between Korea and Japan over the Dokdo issue and conflict escalating with China over Ieo do Islet, the US Navy has confronted situation where it cannot fully concentrate on the security of the Korean peninsula, which leads to need for strengthening of South Korea's naval forces. Let's look at naval forces of neighboring countries. North Korea is threatening South Korean navy with its increased asymmetric forces, including submarines. China has achieved the remarkable development of naval forces since the promotion of 3-step plan to strengthen naval power from 1989, and it now retains highly modernized naval forces. Japan makes an investment in the construction of stat of the art warship every year. Since Japan's warship boasts of its advanced performance, Japan's Maritime Self Defense Force is evaluated the second most powerful behind the US Navy on the assumption that submarine power is not included in the naval forces. In this situation, naval power construction of South Korean navy should be done in phases, focusing on the followings; First, military strength to repel the energy warship quickly without any damage in case of battle with North Korea needs to be secured. Second, it is necessary to develop abilities to discourage the use of nuclear weapons of North Korea and attack its nuclear facilities in case of emergency. Third, construction of military power to suppress armed provocations from China and Japan is required. Based on the above naval power construction methods, the direction of power construction is suggested as follows. The sea fleet needs to build up its war potential to defeat the naval forces of North Korea quickly and participate in anti-submarine operations in response to North Korea's provocations. The task fleet should be composed of 3 task flotilla and retain the power to support the sea fleet and suppress the occurrence of maritime disputes with neighboring countries. In addition, it is necessary to expand submarine power, a high value power asset in preparation for establishment of submarine headquarters in 2015, develop anti-submarine helicopter and load SLAM-ER missile onto P-3C patrol aircraft. In case of maine corps, division class military force should be able to conduct landing operations. It takes more than 10 years to construct a new warship. Accordingly, it is necessary to establish plans for naval power construction carefully in consideration of reality and future. For the naval forces to safeguard maritime sovereignty and contribute to national security, the acquisition of a huge budget and buildup of military power is required. In this regard, enhancement of naval power can be achieved only through national, political and military understanding and agreement. It is necessary to let the nation know that modern naval forces with improved weapon system can serve as comprehensive armed forces to secure the command of the sea, perform defense of territory and territorial sky and attack the enemy's strategic facilities and budget inputted in the naval forces is the essential source for early end of the war and minimization of damage to the people. If the naval power construction is not realized, we can be faced with a national disgrace of usurpation of national sovereignty of 100 years ago. Accordingly, the strengthening of naval forces must be realized.

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정부대행검사기관 선박검사원의 자격기준에 관한 연구 (Eligibility Standards for Recognized Organization Personnel Responsible for Statutory Survey)

  • 이상일;정민;전해동
    • 해양환경안전학회지
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    • 제26권4호
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    • pp.366-373
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    • 2020
  • 선박안전법 제77조 및 동법 시행규칙 제97조의2에 따르면 정부대행검사기관 선박검사원은 일반적으로 특정분야의 학력과 경력을 가지고 있거나 국가기술자격법상 면허를 취득해야 함을 알 수 있다. 하지만, 해사 고등학교 졸업생 및 해기사 단기양성과정 이수생의 경우 수·해양계 및 조선관련 학과를 졸업하지 않아 선박검사원 자격기준을 만족하지 못하고 있는 실정이다. 영국, 미국, 캐나다 등 주요 해운국가는 우리나라와 같은 규정이 없이 IACS 규정을 준용하고 있고, 일본의 경우 선박안전법에서 선박검사원의 자격 요건을 삭제하였다. 특히, IMO 및 IACS의 선박검사원 자격기준은 공학 또는 자연 과학 분야와 관련하여 고등교육기관에서 최소 2년 이상의 과정을 이수; 또는 해상 또는 해사 교육기관에서 자격을 취득하고 자격 있는 선박 사관으로 승선한 경력이 있는 경우; 그리고 관련 업무를 수행하는데 적합한 영어실력을 요구하는 것이 일반적이다. 이에 공무원임용시험령 제17조에 따라 학력제한을 금지하고 있는 점, 영국 및 일본의 선박검사관 응시자격에 학력제한이 없는 점 등을 감안하면 해사 고등학교 졸업생의 경우 충분한 승선경력 및 교육훈련을 쌓는다면 선박검사원 응시자격을 인정할 수 있을 것으로 판단된다. 또한 해기사 단기양성기관의 수료생의 경우 입학자격이 전문학사 이상의(3급 면허 취득학생의 경우) 학력을 보유하도록 되어 있고, 수료 후 일정한 승선경력을 갖추게 되므로 선박검사원 응시자격을 인정할 수 있을 것으로 판단된다.

국군간호사관학교 교육과정 개선을 위한 기초 연구 (A Study on Curriculum Improvement of the Korea Army Nursing Academy)

  • 고자경
    • 대한간호학회지
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    • 제13권2호
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    • pp.22-43
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    • 1983
  • 1. Need for and Purpose of the Study. There is an increasing demand for curriculum improvement of the Korean Army Nursing Academy (KANA), since it was upgraded into 4-year institution of higher learning from 3-year one. In particular, it is strongly advocated that the KANA needs the outside expertise for its curriculum improvement-namely not only from the internal military view of points but also from the viewpoints of professional educational society, In line with such a necessity for the study, this study was aimed at 1) analyzing the current actual practices of KANA'S curriculum, 2) investigating the desired practices of KANA'S curriculum, and 3) identifying the discrepancy between the actual and desired practices of curriculum. 2. Problems for the Study This study had 4 problems to be answeared as follows: 1) What are the actual curriculum practices of KANA? 2) What are the desired curriculum practices of KANA? 3) How are the extents of perception of actual and desired curriculum different in four groups (student, faculty & administrator, nurse, and medical doctor in militay hospital) ? 4) What are the restraining forces that impede the change from actual to desired curriculum practices? 5) What are the relationships of curriculum component,』 in actual and desired curriculum practices? 3. Methods and Procedures This study was conducted by means of document analysis in addition to literature review and by means of needs assessment questionnaire which was developed by the researcher. The questionnaire included 62 statments with 7 questions for demographic data collection. The needs assessment questionnaire was managed to a total of 243 subjects (100 students, 46 faculty & administrators, 55 nurses, and 42 medical doctors), The collected data were treated using SPSS computer system so as to calculate mean scores, standard deviations, and correlation coefficients. The significance test was made through t-test and one-way ANOVA. The statistical significance level was set at both .05 and .01 level. 4. Major findings The major findings in this study are as follows: 1) The score of desired practices was significantly greater than that of actual practices, representing a strong need for curriculum betterment. 2) There were significant differences in the perceptions of actual practices as well as desired practices among four groups (student, faculty & administrater, nurse, and medical doctor). 3) The most frequently selected restraining forces were army's inherent character, economical limitation, and educational expertise limitations. 4) Such variables as sex, position attachment to the KANA and grade made a statistically significant effect on the perception of desired curriculum practice, while the variables like marrige, position, and military class made it on the perception of actual curriculum practice. 5) The coefficients among the curriculum components were lower in perception of the actual curriculum practices than those in the desired practices. 5. Conclusions The conclusions based on the major findings of this study are as follows: 1) The current curriculum development procedure of the KANA is not consistent with the theoretical frame of systematic development sarategy of curriculum. 2) There are wide conflicts among the groups who are supposed to participate in curriculnm development, concerning the actual and desired practices of KANN'S curriculum. 3) A great deal of need for curriculum improvement for the KANA is clearly felt, and in particular, in the process of teaching and learning. 4) Each component of curriculum is not intergrated into a whole development procedure, being segregated each other. 5) For better curriculum improvement, such restraining forces as financial and professional limitations should be eliminated. 6. Recommendations 1) For Further Research a. There is a need to replicate this study after in-depth statistical analysis of each item of need assessment questionnaire, and with more representative subjects. b. A study should be conducted which. has its focus on the analysis of restraining forces for the change from actual to desired curriculum practices of the KANA. 2) For KANA'S Curriculum Improvement a. There is a need to promote the professional expertise of the participants in curriculum development and the communication among them. b. It is desirable to establish an institution or section of administration, which is soley in charge of curriculum development. c. To better develop KANA's curriculum not only faculty and administrators but also students should be encouraged to participate in development process, while the military medical doctors' participation should be carefully considered.

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H. pylori Infection 감염과 위암 발생 (H. pylori Infection and Gastric Carcinogenesis)

  • 한상욱;조용관;정재연;박현진;김영배;남기택;김대용;주희재;최준혁;김진홍;이기명;김명욱;함기백
    • Journal of Gastric Cancer
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    • 제2권2호
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    • pp.73-80
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    • 2002
  • In spite the fact that H. pylori infection might be the causative organisms of acute and chronic gastritis, peptic ulcer diseases and the definition as the class I carcinogen by WHO IARC, still debates exist about the relationship between H. pylori and gastric carcinogenesis. Epidemiological and animal studies demonstrated a link between gastric cancer and chronic infection with H, pylori, but the exact mechanism responsible for the development of gastric cancer in H. pylori-infected patients still remain obscure. In order to declare the clear association, definate evidences like that decrement in the incidence of gastric cancer after the eradication of H. pylori in designated area compared to noneradicated region or the blockade of specific mechanism acting on the carcinogenesis by H. pylori infection. The other way is to identify the upregulating oncogenes or downregulating tumor suppressor genes specifically invovled in H. pylori-associated carcinogenesis. For that, we established the animal models using C57BL/6 mice strain. Already gastric carcinogenesis was developed in Mongolian gerbils infected with H. pylori, but there has been no development of gastric cancer in mice model infected with H. pylori after long-term evaluation. Significant changes such as atrophic gastritis were observed in mice model. However, we could observe the development of mucosal carcinoma in the stomach of transgenic mice featuring the loss of TGF-beta sig naling by the expressions of dominant negative forms of type II receptor specifically in the stomach. Moreover, the incidence of gastric adenocarcinoma was significantly increased in group administered with both MNU and H. pylori infection than MNU alone, signifying that H. pylori promoted the gastric carcinogenesis and there might be host susceptibility genes in H. pylori-associated gastric carcinogenesis. Based on the assumption that chronic, uncontrolled inflammation might predispose to carcinogenesis, there have been several evidences showing chronic atrophic gastritis predisposed to gastric carcinogenesis in H. pylori infection. Although definite outcome of chemoprevention was not drawn after the longterm administration of anti-inflammatory drug in H. pylori infection, the actual incidence of atrophic gastritis and molecular evidence of chemoprevention could be obtained. Selective COX-2 inhibitor was effective in decreasing the development of gastric carcinogenesis provoked by H. pylori infection and carcinogen like in chemoprevention of colon carcinogenesis.

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해수유통 중인 간척담수호 화성호에서 식물플랑크톤의 군집과 적응전략에 대한 수문학적 영향 (The Effect of Hydrology on Phytoplankton Assemblages and Its Adaptive Strategies in Lake Hwaseong, Estuarine Reservoir with Seawater Exchange, Korea)

  • 송태윤;유만호;이인호;강의태;김미옥;최중기
    • 생태와환경
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    • 제47권2호
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    • pp.71-81
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    • 2014
  • 해수유통 중인 화성호에서 수문학적 변동이 식물플랑크톤 군집과 적응전략에 미치는 영향을 파악하기 위하여 2012년 5월부터 10월까지 7회에 걸쳐 식물플랑크톤 종조성, 생물량, 환경변수를 조사하였다. 수문학적 이벤트 (해수유통, 강수량)는 화성호의 급격한 염분변동 (2.9~29.1 psu)과 함께 영양염, 투명도를 조절하였다. 식물플랑크톤 종조성은 매 조사마다 강 (class) 수준에서 급격히 변하였고, 클로로필-a는 $9.7{\sim}104.1{\mu}g\;L^{-1}$의 범위로 6월에 낮고 9월에 높았다. 다변량 분석결과, 식물플랑크톤 천이는 4개의 시기로 구분되었다. Phase I (5~6월)은 해수유통이 빈번한 고염-중온 시기로, 작은 크기의 Gymnodinium sp., Heterosigma akashiwo이 우점하였다. Phase II (7월, 9월)에는 집중호우와 바람의 영향으로 Cylindrotheca closterium가 우점하였고, Phase III (8월)에는 저염-고온 시기로 Oscillatoria spp.가 우점하였으며, Phase IV (10월)는 해수유통이 다시 증가하고 수온이 급감하면서 작은 편모조류인 unid. cryptomonad가 우점하였다. 화성호 식물플랑크톤 군집은 형태적, 생리적 특성에 따라 구분되는 세가지 적응전략, 즉 C (colonist-invasives), S (stress-tolerants), R (ruderals)전략에 따라 구분되었다. Phase I와 IV의 우점종은 CR-전략종으로써, 약한 성층조건을 선호하는 작은 크기의 기회종이였고, Phase II와 III의 우점종은 R-전략종으로써, 유입하천수의 교란에 적응된 중간 크기의 종이다. 이 결과는 향후 해수유통차단에 의한 성층강화가 현재의 식물플랑크톤 군집을 더 작은 편모조류의 극우점으로 변화시킬 수 있음을 보여주었다. 결론적으로 화성호의 수문학적 이벤트(해수유통, 강수량)는 염분, 영양염, 성층환경 교란을 조절함으로써 식물플랑크톤의 천이와 대발생을 이끄는 중요한 요인임을 제시한다.

Serum Beta-2 Microglobulin: a Possible Marker for Disease Progression in Egyptian Patients with Chronic HCV Related Liver Diseases

  • Ouda, SM;Khairy, AM;Sorour, Ashraf E;Mikhail, Mikhail Nasr
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권17호
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    • pp.7825-7829
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    • 2015
  • Background: Egypt has the highest prevalence of HCV infection in the world (~14.7%). Around 10-15% of HCV-infected persons will advance to cirrhosis within the first 20 years. The incidence of HCC is expected to grow in the next two decades, largely due to HCV related cirrhosis, and detection of HCC at an early stage is critical for a favorable clinical outcome. No simple reliable non-invasive marker has been available till now. B2M, a non-glycosylated polypeptide composed of 99 amino acids, is one of the components of HLA class I molecules on the surfaces of all nucleated cells. It has been reported that the level of serum B2M is elevated in patients with chronic hepatitis C and HCV-related HCC when compared to HCV-negative patients or healthy donors. Determining the clinical utility of serum B2M as a marker for disease progression in Egyptian patients with HCV related chronic hepatitis, cirrhosis and hepatocellular carcinoma was the aim of the present study. Materials and Methods: In this analytical cross sectional study 92 participants were included in 4 equal groups: Group (1) non cirrhotic chronic HCV; Group (2) HCV related liver cirrhosis; Group (3) HCC on top of HCV,; and Group (4) healthy controls. History taking, clinical examination, routine labs and abdominal ultrasound were conducted for all patients, PCR and Metavir scores for group (1) patients, and triphasic CT abdomen and AFP for Group (3) patients. B2M levels were measured in serum with a fully-automated IMX system. Results: The mean serum B2M level of Group (1) was $4.25{\pm}1.48{\mu}g/ml$., Group (2) was $7.48{\pm}3.04$, Group (3) was $6.62{\pm}2.49$ and Group (4) was $1.62{\pm}0.63$. Serum B2M levels were significantly higher in diseased than control group (p<0.01) being significantly higher in cirrhosis ($7.48{\pm}3.04$) and HCC groups ($6.62{\pm}2.49$) than the HCV group ($4.25{\pm}1.48$) (p<0.01). There was a significant correlation between B2M Level and ALK, total and direct bilirubin and INR (p<0.05), and a significant inverse correlation between B2M level and albumin, total proteins, HB andWBCS values (p<0.05). There was no significant correlation between B2M level and viral load or Metavir score, largest tumour size or AFP (p>0.05). The best B2M cut-off for HCV diagnosis was 2.6 with a sensitivity of 100%, a specificity of 92%, a positive predictive value (PPV) of 97% and a negative predictive value (NPV) of 100%. The best B2M cut-off for HCC diagnosis was 4.55 which yielded sensitivity, specificity, positive predictive value, negative predictive values of 74%, 62%, 39.5, 87.8% respectively (p-value <0.01) while best cut-off for cirrhosis was 4.9, with sensitivity 74 % and specificity 74%.The sensitivity for HCC diagnosis increased upon B2M and AFP combined estimation to 91%, specificity to 79%, NPV to 95% and accuracy to 83%. Conclusions: Serum B2M level is elevated in HCV related chronic liver diseases and may be used as a marker for HCV disease progression towards cirrhosis and carcinoma.

암반조간대 대형저서동물군집에 대한 씨프린스호 유류 유출사고 영향 평가 (Assessment of the Impacts of 'Sea Prince' Oil Spill on the Rocky Intertidal Macrobenthos Community)

  • 신현출;이정호;임경훈;윤성명;고철환
    • 환경생물
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    • 제26권3호
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    • pp.159-169
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    • 2008
  • 아라비안 원유 86,886.2톤 이상을 선적한 유조선 Sea Prince호는 태풍 페이를 피하다가 1995년 7월 23일 소리도 인근 해안에 좌초되었다. 이후 4,155.3톤의 원유와 979.9톤의 엔진오일 (벙크C, 벙크A)이 유출되었으며, 유출유는 주로 북동방향으로 확산되어 소리도와 남해도를 중심으로 수백킬로미터의 해안이 기름으로 뒤덮였다. 본 연구는 Sea Prince 유류 유출 사고 2년 후, 유류의 영향이 가장 심각했던 지역부터 영향을 받지 않은 지역까지 유류 확산 경로를 따라 조간대 대형저서동물군집에의 영향을 알아보기 위하여 수행되었다. 현장 조사는 사고 2.5년 후인 1998년 2월부터 11월까지 계절별로 Sea Prince 유출유가 뒤덮인 연안을 대상으로 7개 지역의 암반조간대를 선정하여 실시하였다. 조사기간 중 11개 동물문이 채집되었으나, 이중 해조 덤불속에서 채집된 단각류와 등각류 등의 일부 종은 미동정되었다. 동정된 종은 총 5문 9강 65과에 속하는 158종이다. 연체동물이 100종(63.3%)으로 가장 많은 종 수가 채집되었고, 다음은 갑각류 38종(24.1%), 극피동물 12종(7.6%), 해면동물 5종(3.2%), 자포동물 3종(1.9%)이 채집되었다. 소리도 덕포(Sea Prince 좌초 지역)에서 계절에 따라 28$\sim$35종으로 가장 출현종수가 적었다. 출현종수는 덕포에서 가막만쪽으로 가면서 증가하였으며, 소횡간도에서 가장 많았다. 특히 소리도 덕포에서는 다른 지역에 비해 해면동물이나 자포동물과 같은 부착동물의 종 수가 매우 적었다. 상부조간대의 서식밀도와 생물량은 유류 영향이 적은 지역으로 갈수록 증가하였으나, 중부조간대의 생물량은 오히려 감소하였다. 조사지역의 무척추동물 생물량은 부착동물의 양에 좌우되었다. 최우점종은 조무래기따개비 (Chthmallus challengeri), 총알고등(Littorina brecicula), 담치류이었다. 상부조간대의 조무래기따개비와 총알고등의 생물량은 소리도의 좌초지역에서 가장 높았으며, 이 곳에서 멀어질수록 감소하였다. 반면에 중부조간대의 담치류는 반대의 경향을 보였는데, 이는 소리도 좌초지역에서 담치류의 개체크기가 다른 지역에 비해 크기 때문이다. 군집분석 결과로는 유류의 영향이 뚜렷이 나타나지 않았다. 생태지수와 집괴분석 결과 조고에 따라서는 뚜렷한 차이를 보이는 반면에 유류 경로에 따라서는 의미있는 결과를 보이지 않았다. 이는 Sea Prince사고 이후 유류확산 지역에서 군집 수준에서는 어느 정도 회복되었음을 의미하는 것으로 보인다. 그러나 우점 부착동물의 개체군이나 개체 수준에서는 유류 사고 이후 회복에 더 많은 시간이 걸림을 보여준다고 할 수 있다.

터널형 2급와동 충전재의 탄성계수와 전단결합강도 및 수복치의 변연융선 파절강도에 관한 연구 (ELASTIC CONSTANTS, SHEAR BOND STRENGTH OF TUNNEL RESTORATIVE MATERIALS AND MARGINAL RIDGE STRENGTH OF RESTORED TEETH)

  • 이가연;박영준;양규호
    • 대한소아치과학회지
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    • 제23권3호
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    • pp.746-763
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    • 1996
  • An alternative design to conventional class II cavity preparation for proximal carious lesions is the tunnel preparation. It preserves the marginal ridge intact, thus making it possible to maintain the natural contact relationship with the adjacent tooth and minimize tooth reduction. This in vitro study was purposed to evaluate the effect of the materials' elastic constants and shear-bond strength on the marginal ridge fracture resistance of teeth restored by the tunnel technique, and to find the materials of choice for tunnel restorations. $Resinomer^{(R)}$, $Ketac-silver^{(R)}$, $Miracle-Mix^{(R)}$, and Tytin were used as restorative material. The elastic constants of each restorative material were evaluated by ultrasonic pulse measurement. Young's modulus and bulk modulus of the restorative materials were evaluated in three specimens for each material type. The shear-bond strength of the restorative materials to the dentin surface was measured after thermocycling 400 times between 6 and $60^{\circ}C$, using ten specimens for each material type. For measuring marginal ridge strength, 60 sound extracted molar teeth were distributed into six groups by size. Sound molar teeth were used as a Control group and unfilled prepared teeth were grouped as Unrestored. Another four groups were named Resinomer group, Ketac-Silver group, Miracle Mix group, and Tytin group by type of restorative material. Tunnel cavity preparation was done with ' 1/2, 2, and 4 round burs in sequence. Initial access to proximal surface was made through an occlusal access preparation started at least 2mm from the marginal ridge, and the proximal opening was formed about 2.5mm below the marginal ridge. After restoration and thermocycling, marginal ridge strength was measured using a universal testing machine. The results were as follows: 1. The Young's modulus of $Tytin^{(R)}$ was 63.95 GPa, followed by $Ketac-Silver^{(R)}$ 27.60 GPa, $Miracle-mix^{(R)}$ 18.48 GPa, and $Resinomer^{(R)}$ 10.74 GPa showing significant differences between the groups(P<0.05). The bulk modulus of the materials showed the same order as Young's modulus. The value of $Tytin^{(R)}$ showed 59.57 GPa indicating that it will deform less than other materials under the same stress. It was followed by $Ketac-Silver^{(R)}$ 23.57 GPa, Miracle $Mix^{(R)}$ 12.50 GPa, and $Resinomer^{(R)}$ 11.60 GPa. 2. The Resinomer group had a shear-bond strength of 7.41 MPa which was significantly higher than those of the Ketac-Silver group (1.80 MPa) and the Miracle Mix group (2.84 MPa) (P<0.01). All the specimens of Tytin group detatched from the dentin surface during thermocycling. 3. The mean marginal ridge strength of the Unrestored group(46.14 kgf) was significantly lower than that of the Control group (84.24 kgf) (P<0.01). The marginal ridge strength of teeth restored by the tunnel technique was, in order, Ketac-Silver group 74.06 kgf, Miracle Mix group 73.36 kgf, Resinomer group 63.47 kgf, and Tytin group 58.76 kgf. The Ketac-Silver, Miracle Mix, and Resinomer groups showed no significant difference with the Control group (P>0.05), but the Tytin group showed significantly lower strength compared to the Control group(P<0.05). The results showed that the marginal ridge strength of the teeth restored by the tunnel technique was not significantly lower than that of sound teeth. They also demonstrated that the bonding strength of the restorative material to the tooth surface should be high and the modulus of elasticity should not be lower than that of the tooth in order to restore the marginal ridge strength to its natural condition.

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