• Toxicological Research
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• 제33권2호
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• pp.107-118
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• 2017

Although alternative test methods based on the 3Rs (Replacement, Reduction, Refinement) are being developed to replace animal testing in reproductive and developmental toxicology, they are still in an early stage. Consequently, we aimed to develop alternative test methods in male animals using mouse spermatogonial stem cells (mSSCs). Here, we modified the OECD TG 489 and optimized the in vitro comet assay in our previous study. This study aimed to verify the validity of in vitro tests involving mSSCs by comparing their results with those of in vivo tests using C57BL/6 mice by gavage. We selected hydroxyurea (HU), which is known to chemically induce male reproductive toxicity. The 50% inhibitory concentration ($IC_{50}$) value of HU was 0.9 mM, as determined by the MTT assay. In the in vitro comet assay, % tail DNA and Olive tail moment (OTM) after HU administration increased significantly, compared to the control. Annexin V, PI staining and TUNEL assays showed that HU caused apoptosis in mSSCs. In order to compare in vitro tests with in vivo tests, the same substances were administered to male C57BL/6 mice. Reproductive toxicity was observed at 25, 50, 100, and 200 mg/kg/day as measured by clinical measures of reduction in sperm motility and testicular weight. The comet assay, DCFH-DA assay, H&E staining, and TUNEL assay were also performed. The results of the test with C57BL/6 mice were similar to those with mSSCs for HU treatment. Finally, linear regression analysis showed a strong positive correlation between results of in vitro tests and those of in vivo. In conclusion, the present study is the first to demonstrate the effect of HU-induced DNA damage, ROS formation, and apoptosis in mSSCs. Further, the results of the current study suggest that mSSCs could be a useful model to predict male reproductive toxicity.

• Journal of Nutrition and Health
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• 제49권6호
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• pp.401-410
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• 2016

자화수는 가격이 비싸지 않고 쉽게 만들 수 있으며 환경 친화적인 음용수임에도 불구하고 자화수 섭취의 건강상의 유익에 관해서는 과학적인 문헌이 매우 제한적이다. 본 연구는 유전적 소인에 의해 제2형 당뇨병이 발현되는 모델인 db/db 마우스 6주령 14마리를 당뇨군과 자화수군으로 나누어 각 7마리씩 배치하고, 이형접합체 마우스 10마리를 대조군으로 하여 총 3군으로 나누어 16주 동안 자화수를 투여하였다. 혈당 강하 효과를 보기 위해 공복혈당, 인슐린 농도, 내당능 검사, 당화 헤모글로빈을 측정 하였고, DNA 손상 감소 효과, 항산화 상태를 알아보았다. 당뇨군과 자화수군의 혈당치는 대조군에 비해 유의적으로 높았으며, 당뇨군의 혈당은 자화수 섭취 16주까지 높게 지속되었으나 자화수군의 혈당은 섭취 10주 후부터 유의적으로 감소하였다. 혈중 당화헤모글로빈 함량도 마찬가지로 대조군보다 당뇨군에서 증가하였고 자화수군에서는 유의적으로 감소하였으나 경구 당부하 검사 결과, 혈당 곡선하면적 (area under the curve, AUC)은 당뇨군과 자화수 투여군 사이에 유의적인 차이를 보이지 않았다. 당뇨쥐의 DNA 손상 정도는 세 가지 지표 (DNA in tail, tail length, tail moment) 모두 자화수군이 당뇨군에 비해 유의적으로 감소하였으며 이러한 효과는 혈액과 간에서 모두 나타났다. 적혈구 항산화 효소인 SOD, GSH-Px glutathione peroxidase 활성도는 대조군, 당뇨군, 자화수군 간에 차이를 보이지 않았고, 혈장 총항산화능인 TRAP 수준도 자화수 섭취로 인한 차이를 볼 수 없었다. 결론적으로 자화수 투여가 db/db mouse를 사용한 제2형 당뇨의 혈당 강하를 포함한 glycemic control에 유리한 개선효과를 보일 뿐 아니라 혈액과 간의 DNA 손상 감소효과까지 보임을 확인하였다. 그러나 그 기전에 대해서는 확실하게 규명하지 못하였으므로 앞으로 자화 수음용 효과를 뒷받침할 더욱 깊고 다양한 기전 연구가 수행되어야 할 것이다.

• 호스피스학술지
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• 제2권2호
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• pp.28-48
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• 2002

The advances of medical technologies have not only prolonged human life span, but also extended suffering period for the patients with incurable medical diseases. Hospice movement was developed to help these patients keep dignity and lives peaceful at the end of their life. Since many patients prefer to spend the last moment of life at home with their family, hospice home care has become very popular worldwide. The purpose of this study for a promotion and development of hospice home care in Korea, and features basic research on medical profession's knowledge and attitudes to hospice home care. This study which was used for the research questionnaires developed by the researcher that were answered by 100 physicians and 127 nurses in a general hospital. Data were collected from April 22, 2002 to May 10, 2002. The SPSS was used to make a comparative analysis of the frequency, percentile, ANOVA, and x2-test. The results of the study were as follows; 1.The medical profession showed high level of knowledge of the definition and philosophy of hospice. However, the physician group of the examinees showed insufficient knowledge of the fact that hospice care includes bereavement care, while the nurse group's response to the same question showed a significant difference(x2=10.752, p=.001). 2.For whom the hospice home care is provided, 95.6% of the respondents showed very high level of knowledge as answering that the incurable terminal illness patients and their families are the beneficiaries of hospice care. The respondents counted nurses, volunteers, pastors, physicians and social workers, consecutively, as hospice care providers. More nurse were positive toward pastors than physicians in regarding as a hospice care provider by a significant difference(x2=11.634, p=.001). 3.For when to referral hospice home care to the patients, only 34.2% answered that patients with less than 6 months of survival time are advised to receive hospice care, reflecting very low level of knowledge. 23.0% of the physicians and 48.0% of the nurses answered that hospice care should be provided when death is imminent, making a significant difference between the two groups(x2=6.413, p=.000). 4.To promote hospice activities, 87.2% pointed out that it is crucial to make general people, including those engaging in the medical field, more aware of hospice. 79.7% answered that a national hospice management should be developed, marking a significant difference between the physician group and nurse group(x2=10.485, p=.001). 5.Advantages of hospice home care are 87.2% responded that patients can have better rest at home receiving hospice home care. Economical merit was brought forward as one of the advantages also, where there was a significant difference between the physicians group and nurse group(x2=7.009, p=.008). 6.The medical professions' attitude to hospice home care are 92.8% of the physicians answered that they would advise incurable terminally ill patients to be discharged from hospital, with 44.3% of them advising the patients to receive hospice home care after leaving the hospital. From the nurses' point of view, 20.9% of the terminally ill patients are being referred to hospice home care after discharge, which makes a significant difference from the physicians' response(x2=19.121, p=.001). 7. 30.6% of physicians have referred terminally ill patients to hospice home care, 75.9% of whom were satisfied with their decision. Those physicians who have never referred their patients to hospice home care either did not know how to do it(66.7%) or were afraid of losing trust by giving the patients an impression of giving up(27.3%). 94.9% of the physicians responded that they would refer their last stage patients to a doctor who is involving palliative care. 8.Only 36.2% of nurses have suggested to physicians that refer the terminally ill patients discharged from the hospital to hospice home care. Once suggested, 95.8% of the physicians have accepted the suggestion. Nurses were reluctant to suggest hospice home care to the physicians, as 48.8% of the nurses said they did not want to. From the result of this study the following conclusion can be drawn, the medical profession's awareness of general hospice care has been increased greatly compared to the results of the previously performed studies. However, this study result also shows that their knowledge of hospice home care is not good enough yet. There is a need for high recommended that medical education institute and develop regular courses on various types of hospice care. Medical field training courses for physicians and nurses will be very helpful as well. It is also important to train hospice experts such as palliative physicians and develop a national hospice management urgently in order to improve the hospice care in Korea.

• 농업과학연구
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• 제14권1호
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• pp.98-133
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• 1987

The mechanical and rheological properties of agricultural materials are important for engineering design and analysis of their mechanical harvesting, handling, transporting and processing systems. Agricultural materials, which composed of structural members and fluids do not react in a purely elastic manner, and their response when subjected to stress and strain is a combination of elastic and viscous behavior so called viscoelastic behavior. Many researchers have conducted studies on the mechanical and rheological properties of the various agricultural products, but a few researcher has studied those properties of rice plant, and also those data are available only for foreign varieties of rice plant. This study are conducted to experimentally determine the mechanical and the rheological properties such as axial compressive strength, tensile strength, bending and shear strength, stress relaxation and creep behavior of rice stems, and grain detachment strength. The rheological models for the rice stem were developed from the test data. The shearing characteristics were examined at some different levels of portion, cross-sectional area, moisture content of rice stem and shearing angle. The results obtained from this study were summarized as follows 1. The mechanical properties of the stems of the J aponica types were greater than those of the Indica ${\times}$ Japonica hybrid in compression, tension, bendingand shearing. 2. The mean value of the compressive force was 80.5 N in the Japonica types and 55.5 N in the Indica ${\times}$ Japonica hybrid which was about 70 percent to that of the Japonica types, and then the value increased progressively at the lower portion of the stems generally. 3. The average tensile force was about 226.6 N in the Japonica types and 123.6 N in the Indica ${\times}$ Japonica hybrid which was about 55 percent to that of the Japonica types. 4. The bending moment was $0.19N{\cdot}m$ in the Japonica types and $0.13N{\cdot}m$ in the Indica ${\times}$ Japonica hybrid which was 68 percent to that of the Japonica types and the bending strength was 7.7 MPa in the Japonica types and 6.5 MPa in the Indica ${\times}$ Japonica hybrid respectively. 5. The shearing force was 141.1 N in Jinju, the Japonica type and 101.4 N in Taebaeg, the Indica ${\times}$ Japonica hybrid which was 72 percent to that of Jinju, and the shearing strength of Taebaeg was 63 percent to that of Jinju. 6. The shearing force and the shearing energy along the stem portion in Jinju increased progressively together at the lower portions, meanwhile in Taebaeg the shearing force showed the maximum value at the intermediate portion and the shearing energy was the greatest at the portion of 21 cm from the ground level, and also the shearing strength and the shearing energy per unit cross-sectional area of the stem were the greater values at the intermediate portion than at any other portions. 7. The shearing force and the shearing energy increased with increase of the cross-sectional area of the rice stem and with decrease of the shearing angie from $90^{\circ}$ to $50^{\circ}$. 8. The shearing forces showed the minimum values of 110 N at Jinju and of 60 N at Taebaeg, the shearing energy at the moisture content decreased about 15 percent point from initial moisture content showed value of 50 mJ in Jinju and of 30 mJ in Taebaeg, respectively. 9. The stress relaxation behavior could be described by the generalized Maxwell model and also the compression creep behavior by Burger's model, respectively in the rice stem. 10. With increase of loading rate, the stress relaxation intensity increased, meanwhile the relaxation time and residual stress decreased. 11. In the compression creep test, the logarithmic creep occured at the stress less than 2.0 MPa and the steady-state creep at the stress larger than 2.0 MPa. 12. The stress level had not a significant effect on the relaxation time, while the relaxation intensity and residual stress increased with increase of the stress level. 13. In the compression creep test of the rice stem, the instantaneous elastic modulus of Burger's model showed the range of 60 to 80 MPa and the viscosities of the free dashpot were very large numerical value which was well explained that the rice stem was viscoelastic material. 14. The tensile detachment forces were about 1.7 to 2.3 N in the Japonica types while about 1.0 to 1.3 N in Indica ${\times}$ Japonica hybrid corresponding to 58 percent of Japonica types, and the bending detachment forces were about 0.6 to 1.1 N corresponding to 30 to 50 percent of the tensile detachment forces, and the bending detachment of the Indica ${\times}$ Japonica hybrid was 0.1 to 0.3 N which was 7 to 21 percent of Japonica types. 15. The detachment force of the lower portion was little bigger than that of the upper portion in a penicle and was not significantly affected by the harvesting period from September 28 to October 20. 16. The tensile and bending detachment forces decreased with decrease of the moisture content from 23 to 13 percent (w.b.) by the natural drying, and the decreasing rate of detachment forces along the moisture content was the greater in the bending detachment force than the tensile detachment force.

• 한국게임학회 논문지
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• 제4권3호
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• pp.11-20
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• 2004

80, 90년대의 영화에서만 보아오던 가상현실이 과학 및 컴퓨터 기술의 비약적인 발전을 바탕으로 우리에게 가까이 다가오고 있다. 다양한 가상현실 시스템 (VRML, HMD, FishTank, Wall Type, CAVE Type)의 개발과 함께 그 시스템의 발전으로 더욱 현실감 있는 가상현실 구현이 가능해지고 있다. 몰입감이 높은 가상 현실은 이로써 사람들이 일상적으로 경험하기 어려운 환경을 직접 체험하지 않고서도 그 환경에 들어와 있는 것처럼 보여주고 조작할 수 있게 해주는 것이다. 가상현실의 응용분야로는 교육, 고급 프로그래밍, 원격조작, 원격위성 표면탐사, 탐사자료 분석, 과학적 가시화(scientific visualization)등을 들 수 있다. 구체적인 예로서, 탱크 및 항공기의 조종법 훈련, 가구의 배치 설계, 수술 실습, 게임 등 다양하다. 이런 가상현실 시스템에서는 인간 참여자의 실제조작과 가상 작업공간이 하드웨어로 상호 연결된다. 이렇게 상호 연결된 하드웨어로 인간의 오감을 적절하게 자극하여 몰입감을 더하여 준다. 아직 많은 부분이 모자라지만 많은 연구와 노력으로 빠른 시간 안에 거의 인간이 느낄 수 있는 느낌을 가상현실에서도 현실과 같이 느낄 수 있을 것이다. 이 논문에서는 가상현실시스템의 기본적인 정의와 개념 그리고 종류를 알아보고 그 중에서 몰입감이 뛰어난 CAVE형의 가상현실시스템에 대하여 개념분석을 하였고 다음으로 2003년 KISTI(한국과학기술정보연구원)에서 만들어진 경복궁(문화 원형 Content)을 가상현실시스템에서 복원 과정을 Design process를 거쳐 제작되는 과정을 통해 가상현실시스템에서의 VR프로그래밍 방법과 모델링 방법을 제시하였다. 이러한 과정을 통해 몰입형 가상현실 시스템의 활용성에 대해 알아보았고 지금 시점에서 이러한 CAVE형 가상현실 시스템의 활용방안에 대하여 연구해 보았다. 끝으로 가상현실시스템을 활용한 문화재 복원 과정에서 나타난 문제점에 대하여 서술 하고 가상 현실 시스템의 활용 방안을 제시한다.

• 미술이론과 현장
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• 제8호
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• pp.33-58
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• 2009

This paper examines four genre paintings on the subject of child education by Jean-Baptiste-Sim${\'{e}}$on Chardin(1699-1779). The Governess, The Diligent Mother, Saying Grace, and The Morning Toilette garnered critical attention after they were exhibited in the Salon from 1739 to 1741. After the exhibition, the paintings were made into prints and frequently sold to members of the bourgeois class in Paris. The iconographical details of Chardin's genre paintings have, thus far, been compared to Dutch genre pictures of the seventeenth century. Further, most studies conducted on Chardin's paintings focus on formal analysis rather than the historical and social contexts. Through attempting social-contextual readings of Chardin's educational series, this paper argues that the significance of Chardin's painting series of child education lies in his representation of the ideal French bourgeois family and the standard of early childhood education in the eighteenth-century French Enlightenment period. In each of the four child education paintings, Chardin depicted a mother with children in a domestic space. Even though this theme derives from traditional Dutch genre paintings in the seventeenth century, the visual motifs, the pictorial atmosphere and the painting techniques of Chardin all project the social culture of eighteenth century France. Each painting in the child education series exemplifies respectively the attire of a French gentlemen, the social view on womanhood and the education of girls, newly established table manners, and the dressing up culture in a 'toilette' in eighteenth century France. Distinct from other educational scenes in previous genre paintings, Chardin accentuated the naive and innocent characteristics of a child and exemplified the mother's warmth toward that child in her tender facial expressions and gesturing. These kinds of expressions illustrate the newly structured standard of education in the French Enlightenment period. Whereas medieval people viewed children as immature and useless, people in the eighteenth century began to recognize children for their more positive features. They compared children to a blank piece of paper (tabula rasa), which signified children's innocence, and suggested that children possess neither good nor bad virtues. This positive perspective on children slowly transformed the pedagogical methods. Teaching manuals instructed governesses and mothers to respect each child's personality rather than be strict and harsh to them. Children were also allotted more playtimes, which explains the display of various toys in the backgrounds of Chardin's series of four paintings. Concurrently, the interior, where this exemplary education was executed, alludes to the virtue of the bourgeois's moderate and thrifty daily life in eighteenth century France. While other contemporary painters preferred to depict the extravagant living space of a French bourgeoisie, Chardin portrayed a rather modest and cozy home interior. In contrast to the highly decorated living space of aristocrats, he presented the realistic, humble domestic space of a bourgeois, filled with modern household objects. In addition, the mother is exceptionally clad in working clothes instead of fashionable dresses of the moment. Fit to take care of household affairs and children, the mother represents the ideal virtues of a bourgeois family. It can be concluded that the four genre paintings of child education by Chardin articulate the new standards of juvenile education in eighteenth century France as well as the highly recognized social virtues between French bourgeois families. Thus, Chardin's series of child education would have functioned as a demonstration of the ideal living standards of the bourgeois class and their emphasis on early childhood education in the French Enlightenment period.

• 기록학연구
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• 제46호
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• pp.95-152
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• 2015

일상아카이브란 '보통사람들'의 삶과 문화를 구체화, 범주화하여 이에 따라 개인이나 공동체, 더 나아가 한 사회의 기억과 이를 담은 기록물을 수집, 평가, 선별, 보존하는 조직이나 시설, 장소를 말한다. 일기를 비롯해 자서전, 회고록, 편지, 메모 등 실물자료와 온라인 공간에서 주고받는 블로그나 카페 게시물, SNS에 업로드되는 일상의 사진도 여기에 속한다. 이렇게 매 순간 생산되는 일상기록의 수집과 보존에 관한 필요성이 기록학계를 비롯해 다양한 분야에서 제기되고 있다. 특히 일기는 시대를 불문하고 한 개인이 매일같이 경험한 사실과 자아성찰 등을 정리한 글로서 기록의 원천성과 개별성, 유일성 등의 가치가 크게 중요시 되고 있다. 최근 여러 편의 일기들이 발굴, 소개되면서 역사학을 비롯해 다양한 인문사회과학 분야에서도 일기와 기록주체, 생산된 시대 연구가 이루어져왔다. 또한 언어학, 교육학, 심리학 등의 분야에서는 일기에서 관찰되는 언어습관, 문화수용양상, 저자의 감정이나 심리변화 등을 분석한다. 이 글에서는 국내외에서 이루어지는 일기 관련 연구 동향을 정리하고 이 맥락에서 일상기록으로서 "5월12일 일기컬렉션"이 갖는 의미를 찾는다. "5월12일 일기컬렉션"은 매년 5월12일 시민들이 직접 생산, 기증한 일기로 구성되어 있다. 명지대 디지털아카이빙연구소가 2013년 첫 '5월12일 일기수집 이벤트'를 개최한지 3년이 되는 현재 유치원생부터 80대 참가자들이 육필 (그림)일기, 전자문서, 디지털사진/영상, 음성녹음 등 다양한 유형으로 생산된 일기가 2천여 건 수집되었다. 이 글에서는 이렇게 수집된 일기를 정량적으로 분석하고 개별 기록물들이 어떤 내용을 담고 있는지를 살펴본다. 가족, 친구, 학교생활, 진로고민 등 연령별 지역별 직업별로 시민들의 생활상과 진솔한 고민을 읽을 수 있다. 개별 기록물에서 추출되는 키워드와 주제어에 따라 이 일기들이 담고 있는 주제를 더욱 포괄적으로 살펴보고자 한다. 또한 수집된 일기들을 형식과 내용에 따라 연구자료로 언어학, 교육학을 비롯해 역사학, 인류학 등 다양한 학문 분야에서 어떻게 활용될 수 있을지 그 연구 가능성을 제언해본다. 그리고 "5월12일 일기컬렉션"이 일상아카이브로서 수집, 보존되기 위해 필요한 과제가 무엇인지 살펴본다.

• 한국노년학
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• 제29권1호
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• pp.149-175
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• 2009

본 연구는 제도 시행 초기인 2008년 10월 현재 여러 부분에서 동시다발적으로 발생하는 노인장기요양보험 재가서비스의 다양한 문제점과 원인을 파악하여 분석한 후, 그에 대한 개선방안을 마련하는 데 목적이 있다. 연구방법은 크게 선행 연구된 2차 자료를 분석하는 문헌조사와 관련 전문가를 대상으로 하는 서베이 조사방식을 통해 진행되었다. 자료의 분석은 길버트와 스펙트의 정책분석틀에 근거하여 대상자체계, 급여(서비스)체계, 재정체계, 전달체계의 영역으로 구분하여 분석하였다. 본 연구를 통해 도출된 노인장기요양보험 재가서비스의 문제점은 첫째, 대상자체계에서는 가입대상자와 서비스 대상자의 불일치, 수요자 추계의 문제점 및 등급판정 관련 문제 등이 있으며, 둘째, 서비스 체계에서는 서비스 인력의 전문성 결여, 방문요양기관 인력기준 완화로 인한 서비스 질 저하, 서비스 이용시간 제한의 불합리성 및 방문요양 수가의 등급별 균등지급의 문제가 있는 것으로 나타났다. 셋째, 재정체계에서는 본인부담금과 비급여항목으로 인한 이용자 부담과중, 기존운영비 지원 기관에 대한 지원중단으로 인한 서비스의 사각지대 발생 및 구조조정 및 파트타임 증가로 서비스 질 저하 문제가 나타났으며, 마지막으로 전달체계에서는 서비스의 질 관리체계 미비, 재가장기요양기관 남설로 인한 과다 경쟁, 영리적 운영으로 인한 서비스 공공성과 질저하, 대상자 모집의 어려움으로 인한 운영난 및 요양보호사 교육기관 난립으로 인한 과다배출과 부실교육 등의 문제가 있는 것으로 조사되었다. 이상의 결과에 근거하여 다음과 같이 제언하였다. 첫째, 장기적으로 가입자와 서비스 대상자를 일치시킬 필요가 있다. 둘째, 공단직원의 전문성 향상 및 인력충원이 필요하며, 셋째, 등급외자에 대한 효율적 서비스 연계, 넷째, 체계적인 요양보호사 관리시스템 구축 및 서비스 표준지침서 개발, 다섯째, 서비스 내용과 절차에 관한 일부 법규의 수정이 필요하며, 여섯째, 본인부담금의 일부 조정도 필요하다. 일곱째, 노인복지법에 의한 재가시설에 운영비를 지원해야 하며, 여덟째, 관리감독 기관의 모니터링 시스템 강화 및 서비스 제공 기관과 서비스 인력에 대한 평가 체계 마련, 그리고 마지막으로 기관설치 기준의 강화가 필요하다.

• 대한치과보철학회지
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• 제40권1호
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• pp.1-17
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• 2002

The purpose of this study is to examine the possibility of thermal injury to bone tissues during an implant site preparation under the same condition as a typical clinical practice of $Br{\aa}nemark$ implant system. All the burs for $Br{\aa}nemark$ implant system were studied except the round bur The experiments involved 880 drilling cases : 50 cases for each of the 5 steps of NP, 5 steps of RP, and 7 steps of WP, all including srew tap, and 30 cases of 2mm twist drill. For precision drilling, a precision handpiece restraining system was developed (Eungyong Machinery Co., Korea). The system kept the drill parallel to the drilling path and allowed horizontal adjustment of the drill with as little as $1{\mu}m$ increment. The thermocouple insertion hole. that is 0.9mm in diameter and 8mm in depth, was prepared 0.2mm away from the tapping bur the last drilling step. The temperatures due to countersink, pilot drill, and other drills were measured at the surface of the bone, at the depths of 4mm and 8mm respectively. Countersink drilling temperature was measured by attaching the tip of a thermocouple at the rim of the countersink. To assure temperature measurement at the desired depths, 'bent-thermocouples' with their tips of 4 and 8mm bent at $120^{\circ}$ were used. The profiles of temperature variation were recorded continuously at one second interval using a thermometer with memory function (Fluke Co. U.S.A.) and 0.7mm thermocouples (Omega Co., U.S.A.). To simulate typical clinical conditions, 35mm square samples of bovine scapular bone were utilized. The samples were approximately 20mm thick with the cortical thickness on the drilling side ranging from 1 to 2mm. A sample was placed in a container of saline solution so that its lower half is submerged into the solution and the upper half exposed to the room air, which averaged $24.9^{\circ}C$. The temperature of the saline solution was maintained at $36.5^{\circ}C$ using an electric heater (J. O Tech Co., Korea). This experimental condition was similar to that of a patient s opened mouth. The study revealed that a 2mm twist drill required greatest attention. As a guide drill, a twist drill is required to bore through a 'virgin bone,' rather than merely enlarging an already drilled hole as is the case with other drills. This typically generates greater amount of heat. Furthermore, one tends to apply a greater pressure to overcome drilling difficulty, thus producing even greater amount heat. 150 experiments were conducted for 2mm twist drill. For 140 cases, drill pressure of 750g was sufficient, and 10 cases required additional 500 or 100g of drilling pressure. In case of the former. 3 of the 140 cases produced the temperature greater than $47^{\circ}C$, the threshold temperature of degeneration of bone tissue (1983. Eriksson et al.) which is also the reference temperature in this study. In each of the 10 cases requiring extra pressure, the temperature exceeded the reference temperature. More significantly, a surge of heat was observed in each of these cases This observations led to addtional 20 drilling experiments on dense bones. For 10 of these cases, the pressure of 1,250g was applied. For the other 10, 1.750g were applied. In each of these cases, it was also observed that the temperature rose abruptly far above the thresh old temperature of $47^{\circ}C$, sometimes even to 70 or $80^{\circ}C$. It was also observed that the increased drilling pressure influenced the shortening of drilling time more than the rise of drilling temperature. This suggests the desirability of clinically reconsidering application of extra pressures to prevent possible injury to bone tissues. An analysis of these two extra pressure groups of 1,250g and 1,750g revealed that the t-statistics for reduced amount of drilling time due to extra pressure and increased peak temperature due to the same were 10.80 and 2.08 respectively suggesting that drilling time was more influenced than temperature. All the subsequent drillings after the drilling with a 2mm twist drill did not produce excessive heat, i.e. the heat generation is at the same or below the body temperature level. Some of screw tap, pilot, and countersink showed negative correlation coefficients between the generated heat and the drilling time. indicating the more the drilling time, the lower the temperature. The study also revealed that the drilling time was increased as a function of frequency of the use of the drill. Under the drilling pressure of 750g, it was revealed that the drilling time for an old twist drill that has already drilled 40 times was 4.5 times longer than a new drill The measurement was taken for the first 10 drillings of a new drill and 10 drillings of an old drill that has already been used for 40 drillings. 'Test Statistics' of small samples t-test was 3.49, confirming that the used twist drills require longer drilling time than new ones. On the other hand, it was revealed that there was no significant difference in drilling temperature between the new drill and the old twist drill. Finally, the following conclusions were reached from this study : 1 Used drilling bur causes almost no change in drilling temperature but increase in drilling time through 50 drillings under the manufacturer-recommended cooling conditions and the drilling pressure of 750g. 2. The heat that is generated through drilling mattered only in the case of 2mm twist drills, the first drill to be used in bone drilling process for all the other drills there is no significant problem. 3. If the drilling pressure is increased when a 2mm twist drill reaches a dense bone, the temperature rises abruptly even under the manufacturer-recommended cooling conditions. 4. Drilling heat was the highest at the final moment of the drilling process.

• 한국해양학회지:바다
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• 제7권3호
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• pp.108-128
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• 2002

고리, 월성, 울진 그리고 영광해역에서 1992년부터 1996년까지 식물플랑크톤의 생태학적 특성을 이해하고자, 식물플랑크톤의 현존량 및 엽록소 농도가 조사되었고, 무생물학적 환경요인들과의 상관관계를 분석하였다. 고리, 월성, 울진 및 영광해역에서 연구기간동안 총 질소의 평균 농도는 각각 0.101, 0.094, 0.072및 0.108mg/$\ell$이었고 ,인산염은 각각 0.007, 0.008, 0.006 및 0.009mg/$\ell$이었다 N:P ratios는 고리, 월성, 울진 및 영광해역에서 3.2~57.3, 3.1~109.0. 2.6~102.0 및 1.0~165.0으로 극심한 변동을 나타내었다. 또한 부유물질 농도는 각각 평균 18.7, 16.7, 11.6 및 52.7mg/$\ell$이었고, 투명도는 각각 평균 3.8, 5.4, 7.9및 0.7m이었다. 총 현존량은 고리, 월성, 울진 및 영광해역에서 각각 평균 710,659, 687,508, 656,245 그리고 1,278,173ce11s/$\ell$로 영광해역에서 가장 높았으며, 나머지 해역은 서로 유사하였다. 연구해역 모두 전반적으로 높은 현존량을 나타내었으며, 이 중 소형플랑크톤의 현존량은 고리, 월성, 울진 및 영광해역에서 각각 평균 357,546, 333,638, 276,407그리고 592,975ce11s/$\ell$이었으며, 미소플랑크톤의 현존량은 고리, 월성, 울진 및 영광해역에서 각각 평균 353,113, 353,870, 379,838그리고 714,846cells/$\ell$로 영광 해역에서 가장 높게 나타났다. 규조류는 고리, 월성, 울진 및 영광해역에서 각각 평균 282,009, 284,710, 238,758 그리고 574,563cells/$\ell$로 영광해역에서 가장 높았으며, 고리, 월성 및 울진 해역은 봄철에 높고 가을철에 낮은 계절분포를 보인 반면에 영광해역은 여름철에 낮은 현존량을 기록하였다. 와편모조류는 각각 평균 46,078, 35,401, 32,906 그리고 16,749cells/$\ell$로 서해 영광해역이 가장 낮게 나타났고, 고리와 영광해역은 여름철 그리고 울진해역은 가을철에 높은 계절분포를 나타내었다. 엽록소 $\alpha$농도는 연구해역에서 평균 2.16~4.28$\mu\textrm{g}$/$\ell$로 영광해역에서 가장 높게 나타났다. 종 다양성 지수는 연구해역에서 2.11~2.24 이었으며, 동해연안은 겨울철에 불안정하고 여름철에 안정된 군집구조를 이루는 반면에, 서해의 영광해역은 겨울철과 여름철에 안정된 군집구조를 이루고 있었다. 식물플랑크톤 현존량과 무생물학적 환경요인들과의 상관관계 분석결과, 연구해역과 계절에 따라 그 영향의 정도에서 차이를 보이지만, 투명도, 부유물질 및 영양염(N $O_3$$^{-}$-N, P $O_4$$^{3-}$ -P)등이 식물플랑크톤 현존량 분포에 영향을 주는 것으로 나타났다.