• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2003년도 추계학술대회
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• pp.34-63
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• 2003

Occupational and environmental exposure to manganese continue to represent a realistic public health problem in both developed and developing countries. Increased utility of MMT as a replacement for lead in gasoline creates a new source of environmental exposure to manganese. It is, therefore, imperative that further attention be directed at molecular neurotoxicology of manganese. A Need for a more complete understanding of manganese functions both in health and disease, and for a better defined role of manganese in iron metabolism is well substantiated. The in-depth studies in this area should provide novel information on the potential public health risk associated with manganese exposure. It will also explore novel mechanism(s) of manganese-induced neurotoxicity from the angle of Mn-Fe interaction at both systemic and cellular levels. More importantly, the result of these studies will offer clues to the etiology of IPD and its associated abnormal iron and energy metabolism. To achieve these goals, however, a number of outstanding questions remain to be resolved. First, one must understand what species of manganese in the biological matrices plays critical role in the induction of neurotoxicity, Mn(II) or Mn(III)? In our own studies with aconitase, Cpx-I, and Cpx-II, manganese was added to the buffers as the divalent salt, i.e., $MnCl_2$. While it is quite reasonable to suggest that the effect on aconitase and/or Cpx-I activites was associated with the divalent species of manganese, the experimental design does not preclude the possibility that a manganese species of higher oxidation state, such as Mn(III), is required for the induction of these effects. The ionic radius of Mn(III) is 65 ppm, which is similar to the ionic size to Fe(III) (65 ppm at the high spin state) in aconitase (Nieboer and Fletcher, 1996; Sneed et al., 1953). Thus it is plausible that the higher oxidation state of manganese optimally fits into the geometric space of aconitase, serving as the active species in this enzymatic reaction. In the current literature, most of the studies on manganese toxicity have used Mn(II) as $MnCl_2$ rather than Mn(III). The obvious advantage of Mn(II) is its good water solubility, which allows effortless preparation in either in vivo or in vitro investigation, whereas almost all of the Mn(III) salt products on the comparison between two valent manganese species nearly infeasible. Thus a more intimate collaboration with physiochemists to develop a better way to study Mn(III) species in biological matrices is pressingly needed. Second, In spite of the special affinity of manganese for mitochondria and its similar chemical properties to iron, there is a sound reason to postulate that manganese may act as an iron surrogate in certain iron-requiring enzymes. It is, therefore, imperative to design the physiochemical studies to determine whether manganese can indeed exchange with iron in proteins, and to understand how manganese interacts with tertiary structure of proteins. The studies on binding properties (such as affinity constant, dissociation parameter, etc.) of manganese and iron to key enzymes associated with iron and energy regulation would add additional information to our knowledge of Mn-Fe neurotoxicity. Third, manganese exposure, either in vivo or in vitro, promotes cellular overload of iron. It is still unclear, however, how exactly manganese interacts with cellular iron regulatory processes and what is the mechanism underlying this cellular iron overload. As discussed above, the binding of IRP-I to TfR mRNA leads to the expression of TfR, thereby increasing cellular iron uptake. The sequence encoding TfR mRNA, in particular IRE fragments, has been well-documented in literature. It is therefore possible to use molecular technique to elaborate whether manganese cytotoxicity influences the mRNA expression of iron regulatory proteins and how manganese exposure alters the binding activity of IPRs to TfR mRNA. Finally, the current manganese investigation has largely focused on the issues ranging from disposition/toxicity study to the characterization of clinical symptoms. Much less has been done regarding the risk assessment of environmenta/occupational exposure. One of the unsolved, pressing puzzles is the lack of reliable biomarker(s) for manganese-induced neurologic lesions in long-term, low-level exposure situation. Lack of such a diagnostic means renders it impossible to assess the human health risk and long-term social impact associated with potentially elevated manganese in environment. The biochemical interaction between manganese and iron, particularly the ensuing subtle changes of certain relevant proteins, provides the opportunity to identify and develop such a specific biomarker for manganese-induced neuronal damage. By learning the molecular mechanism of cytotoxicity, one will be able to find a better way for prediction and treatment of manganese-initiated neurodegenerative diseases.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2000년도 국제심포지움
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• pp.10-12
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• 2000

Members of the glycoprotein family, which includes CG, LH, FSH and TSH, comprise two noncovalently linked $\alpha$- and $\beta$-subunits. Equine chorionic gonadotropin (eCG), known as PMSG, has a number of interesting and unique characteristics since it appears to be a single molecule that possesses both LH- and FSH-like activities in other species than the horse. This dual activity of eCG in heterologous species is of fundamental interest to the study of the structure-function relationships of gonadotropins and their receptors. CG and LH $\beta$ genes are different in primates. In horse, however, a single gene encodes both eCG and eLH $\beta$-subunits. The subunit mRNA levels seem to be independently regulated and their imbalance may account for differences in the quantities of $\alpha$ - and $\beta$ -subunits in the placenta and pituitary. The dual activities of eCG could be separated by removal of the N-linked oligosaccharide on the $\alpha$-subunit Asn 56 or CTP-associated O-linked oligosaccharides. The tethered-eCG was. efficiently secreted and showed similar LH-like activity to the dimeric eCG. Interestingly, the FSH-like activity of the tethered-eCG was increased markedly in comparison with the native and wild type eCG. These results also suggest that this molecular can implay particular models of FSH-like activity not LH-like activity in the eCG/indicate that the constructs of tethered molecule will be useful in the study of mutants that affect subunit association and/or secretion. A single-chain analog can also be constructed to include additional hormone-specific bioactive generating potentially efficacious compounds that have only FSH-like activity. The LH/CG receptor (LH/CGR), a membrane glycoprotein that is present on testicular Leydig cells and ovarian theca, granulosa, luteal, and interstitial cells, plays a pivotal role in the regulation of gonadal development and function in males as well as in nonpregnant and pregnant females. The LH/CGR is a member of the family of G protein-coupled receptors and its structure is predicted to consist of a large extracellular domain connected to a bundle of seven membrane-spanning a-helices. The LH/CGR phosphorylation can be induced with a phorbol ester, but not with a calcium ionophore. The truncated form of LHR also was down-regulated normally in response to hCG stimulation. In contrast, the cell lines expressing LHR-t63I or LHR-628, the two phosphorylation-negative receptor mutant, showed a delay in the early phase of hCG-induced desensitization, a complete loss of PMA-induced desensitization, and an increase in the rate of hCG-induced receptor down-regulation. These results clearly show that residues 632-653 in the C-terminal tail of the LHR are involved in PMA-induced desensitization, hCG-induced desensitization, and hCG-induced down-regulation. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty. Cells expressing LHR-D556Y bind hCG with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. This mutation enhances the internalization of the free and agonist-occupied receptors ~2- and ~17-fold, respectively. We conclude that the state of activation of the LHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing LHR-L435R is due to the fast rate of internalization of the bound hCG. This statement is supported by the finding that hCG responsiveness is restored when the cells are lysed and signal transduction is measured in a subcellular fraction (membranes) that cannot internalize the bound hormone.

• Journal of Preventive Medicine and Public Health
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• 제12권1호
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• pp.13-23
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• 1979

A study was carried out from October 1977 to September 1978 in order to develope health care delively system which will meet to rural area in Korea. For the study objective a model of health care delivery system of Myun (township) area was developed which is adopted the net-work of village health voluntary worker who will play the role of bridge for communication related with health and illness between families or village people and health subcenter, and :he model health care delivery system net-work was set in the area of Soodong Myun, Yangju Gun. which is the rural health demonstration area of Ewha Womans University since 1972. The activities and attitude of 22 village health voluntary workers were observed and analized. during the study period. The results are as follows; 1. For the field activities of village health voluntary workers. a guide line which is described with specific behavioral objectives was developed and used for not only training of the workers but also evaluation of their field activities. 2. During the study period, the number of 971 village people were served primary health care service by village health voluntary worker and the service was classified largely into symptomatic medications (92%) and preventive measures (8%). 3. Comparative percentage of the number of 894 symptomatic cases cared by village health voluntary workers to 5,695 cases of patient treated by Soodong Health Subcenter during the same period was 15.7%. 4. Annual utility rate of village health voluntary worker by Myun total people was 16.1% but utility rate by Rie was varied from 38.2% to 2.8% which shown there were considerable differences in each Rie. In order to settle the village health care service, the obstructive factors of utility should be detected and their counter measure must be taken. 5. As the health need of village people increases, it is expected that the supplement of drug excluding present sit basic drugs is inevitable, but considering the ability of village health voluntary worker, the selection of additional drugs and education, plan should be carefully studied. 6. It is desirable that a financial resource for supplementary purchase of first aid kit, drugs and materials whould be alloted from village public fund like Saemaeul Women's Club fund, which has already practiced in a few villages in the study area. 7. As pointed out by village health voluntary workers, in order to improve the village health, village leaders should be in the center of it and the cooperation of whole village people is a core of healthful village development, and it is reasonable that the health subcenter backs up these voluntary health activities by village people in techniques. 8. It seems effective that a supplementary education for village health voluntary worker be accomplished by a planned education through regular meetings like worker's monthly meeting and irregular post guide when Myun Health Workers can handle the problems found during the round trip of villages. 9. It is desirable that village health voluntary workers, who are recommended by a civil voluntary organization like Saemael Woman's Club, are charged by natural villagc unit, are given a function of village health care service and used through basic education at health subcenter. 10. It is advisable that the village health voluntary worker's service is compensated not by a form of money, but by other way such as an exemption of medical fee of worker herself or her families in health subcenter can be one method. 11. Daily health activities of each village health voluntary worker should be reported to health subcenter by biweekly or monthly in order to get not only for basic data of the program but also for evaluation the program. It is recomandable that the report form should be simple and clear enough for village health voluntary worker to fill it effectively. 12. Village health care service should be developed into a Saemaeul Movement in which village people actively participate. For this, the appointed function of village health voluntary worker should be absorbed into those of living Environment Betterment Section or Family Planning Section of Saemaeul Women's Club or it is desirable that establish a new section, Village Health Promoting Section and make it involve the appointed functions of those sections mentioned above.

• 지능정보연구
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• 제24권2호
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• pp.21-35
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• 2018

본 논문에서는 스테레오 음악에 오디오 워터마크를 삽입하기 위한 알고리즘을 제안하였다. 스테레오 음악은 2개의 채널을 갖고 있기 때문에 기존 워터마킹 기술은 일반적으로 각 채널을 독립적으로 생각하고 처리하는 경우가 많다. 그러나 스테레오를 모노로 변환하는 과정에서 워터마크의 손실이 발생하는 경우가 많이 발생할 수 있다. 제안한 알고리즘은 스테레오를 모노로 변환하더라도 워터마크의 손실이 발생하지 않도록 워터마크를 삽입할 때 스테레오와 모노변환의 특성을 이용하였다. 제안된 알고리즘에 사용된 오디오 워터마크는 "Copyright"와 "Copy_free"라는 두 가지 정보를 터보코드를 이용하여 생성하였다. 두 워터마크는 9바이트(72비트)로 이루어져 있으며, 오류정정을 위하여 터보코드를 적용하면 222비트로 삽입해야 하는 정보량이 늘어난다. 222비트의 워터마크는 추가적인 오류에 강인하도록 1024비트로 확장하여 최종적으로 스테레오 음악에 삽입할 워터마크로 사용하였다. 평균적으로 SNR은 40dB를 넘어서서 전통적인 양자화 방식보다 10dB 이상의 음질 개선을 가져왔다. 이는 상대적으로 10배의 음질 개선도를 의미하는 것으로 매우 유의미한 결과이다. 또한 워터마크의 추출에 필요한 샘플길이는 1초 이내의 길이면 충분히 추출이 가능하고, 128Kbps의 비트레이트를 갖는 MP3 압축에 대해서도 모두 1초 이내 길이의 음악 샘플로부터 워터마크의 완전한 추출이 가능하였다. 전통적인 양자화 방식이 10초 길이의 샘플을 이용해도 대부분 워터마크의 추출에 실패한 것에 비하면 1/10에 불과한 길이로 워터마크의 추출이 가능하다.

• 한국과학교육학회지
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• 제22권4호
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• pp.796-805
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• 2002

본 연구는 '식물의 구조와 기능' 단원의 학습 전 아동의 지식구조와 학습과정 및 학습 종료 7개월 후까지의 지식구조의 변화를 아동의 학습성향(유의미학습과 암기학습)과 관련지워 조사한 것이다. 연구단원과 관련된 기존의 지식구조를 알아보기 위하여 5학년 아동들에게 1차 개념도를 그리게 하고, 매 4차시 수업후 각각의 개념도를 그리게 했다. 그리고 지식구조의 지속효과를 알아보기 위하여 단원 학습이 종료된 직후와 3개월, 7개월 후에도 각각의 개념도를 그리게 했다. 학습과정 동안에는 기존의 개념도를 근거로 하여 개념도를 그리게 하였으며, 단원 학습 종료 후에는 기존의 개념도가 제시되지 않은 상태에서 개념도를 그리게 하였다. 아동들이 그린 각각의 개념도는 그 당시의 식물의 구조와 기능에 대한 이해 정도를 나타내었다. 초등학교 5학년 아동들은 '식물의 구조와 기능' 단원의 학습에 들어가기 전에 이와 관련된 여러 가지 개념들로 이루어진 사전 지식구조를 가지고 있으나 그 중 과학적으로 타당한 것은 개념도 상에서 2단계의 위계와 5개의 관계에 불과하였다. 한 단원의 학습이 진행되어감에 따라 아동들의 지식구조는 꾸준히 그리고 점진적으로 증가였다. 그러나 이러한 증가는 학습성향에 따라 차이를 보이며, 유의미 학습자가 암기 학습자보다 더 많이 증가하였다(관계, 연관, 예: p < .01, 위계: p < .05). 지식구조의 변화에 있어서 학습성향간에 다소 차이가 있으나 재구조화는 단원 학습의 초기에 높은 빈도로 일어났으며, 말기에는 전혀 일어나지 않았다. 조정은 유의미 학습자보다 암기 학습자에서 더 많이 일어나고 확장은 이와 반대로 유의미 학습자에서 더 많이 일어났다. 암기 학습자의 개념도 점수는 단원 학습을 마친 후 시간이 경과함에 따라 모든 범주에서 차츰 감소하였다. 그러나 유의미 학습자의 경우 단원 학습 후 3개월보다 7개월에서 오히려 소폭 증가했다. 그러므로 대체로 암기 학습자가 학습과정에서 새로이 구축하고자 하는 더 분화되고 정교한 지식구조가 유의미 학습자보다 불안정한 상태에 있으며, 지식구조의 분화 정도도 유의미 학습자에 비해 낮다고 할 수 있다.

• 전자공학회논문지
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• 제54권7호
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• pp.21-28
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• 2017

FPGA 배치 툴 연구는 학계에서도 단순한 가상 아키텍처 모델 가정에서 벗어나 상용 툴처럼 캐리체인이나 광폭함수 멀티플렉서, 메모리/승산기 블록 등의 성능 및 밀도를 향상시키는 소자들을 포함하는 현실적인 모델을 적용하기 시작하였다. 이 때 발생하는 실제적 이슈들을 다룬 사전 패킹, 다층 밀도 분석 등의 기법이 초기 분석적 배치 (Analytic Placement)에 적용되어 밀도를 분산시키면서 배선 길이를 효과적으로 최소화한 연구가 앞서 발표된 바 있다. 더 나아가 궁극적으로는 타이밍을 최적화해야하기 때문에 많은 연구에서는 타이밍 제약 조건을 만족시키기 위한 기법들이 제시되고 있다. 그러나 초기 배치 후 진행되는 배치 적법화 및 배치 개선에서 주로 적용될 뿐 분석적 배치에서 이러한 타이밍 기법을 적용한 사례는 거의 없다. 본 논문에서는 사전 패킹 및 다층 밀도 분석 등의 기법이 구현된 기존 분석적 배치에 타이밍 제약 조건 위반을 검출하고 이를 최소화하는 기법을 결합하는 방안을 소개한다. 먼저 정적 타이밍 검증기를 집적하여 배선 길이가 최소화된 기존 배치 결과의 타이밍을 검사해 보았으며 위반을 감소시키기 위해 신호 도착 시간 (Arrival Time)을 최소화하는 함수를 분석적 배치의 목적 함수에 추가하였다. 이 때 각 클록마다 주기가 다를 수 있기 때문에 각 클록별로 함수를 따로 계산해 합산하는 방안이 제안되었다. 또한, 위반이 없는 클록 도메인의 신호 경로들도 불필요하게 단축될 수 있기 때문에 음수 슬랙 (Negative Slack)을 계산하여 이를 최소화하는 함수를 추가로 제안하여 비교하였다. 영역 분할 기법 (Partitioning)을 기반으로 배선 길이를 최소화하는 기존 배치 적법화를 그대로 사용한 후 타이밍 검증을 통해 초기 분석적 배치 단계에서 타이밍 개선 효과를 분석하였다. 배치 적법화 시 추가적인 타이밍 최적화 기법이 사용되지 않았기 때문에 타이밍 개선이 있다면 이것은 전적으로 분석적 배치의 목적 함수개선에 의한 효과이다. 12개 실용예제에 대해 실험한 결과, 목적 함수에 도착 시간 함수가 적용되었을 때 그렇지 않았을 때보다 최악 음수 슬랙 (Worst Negative Slack)이 평균 약 15% 정도 감소되었으며 음수 슬랙 함수가 적용되었을 때 이보다 약 6%정도 추가로 더 감소됨을 확인하였다.

• 대한공업교육학회지
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• 제38권2호
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• pp.89-113
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• 2013

본 연구에서는 미래 인력 수요 변화에 대하여 효율적 효과적으로 신속 대응하기 위해 가장 기본적으로 갖추어야할 학습자의 태도로 자발적으로 학습에 임할 수 있는 자세를 길러야 한다는 점에 주안점을 갖고 시작하였다. 이를 위해 어떤 외부적인 요인보다 자기학습능력 신장과 지속적인 학습동기 및 의지를 가질 수 있는 적절한 교수-학습 방법의 고안의 필요성과 특성화 고등학교에서 발생되는 여러 가지 수업관련 문제점들을 해결할 수 있는 수업 전략으로 모듈기반의 팀 보조 개별학습(이하, TAI) 모형을 적용하였다. 이를 통해 학습자의 흥미를 이끌어 내고, 학습 지속력을 높여보고자 하였다. 본 연구를 통하여 얻을 수 있는 결론은 다음과 같다. 첫째, 학습 단원을 모듈식으로 구조화하여 학습단계를 진행함으로써 학습적응 능력이 향상되었다. 성취기준(학습목표)은 교과 특성상 실무 현장과 교과 간 연계를 고려하여 교재를 분석하고 재구성하여 모듈식으로 구조화함으로써 모듈식 학습단계의 과정을 통해 단원의 특성 파악과 학습 적응 능력이 향상되었다. 둘째, 모듈 기반의 TAI 모형 적용을 통하여 자기주도적 학습능력과 현장 적응능력의 향상을 가져왔다. 모듈식 학습 방법을 적용하여 종래의 수동적인 학습 환경에서 벗어나 보다 능동적으로 학습하는 자기주도학습을 할 수 있었으며, TAI 모형과 협동학습의 접목으로 함께하는 수업에서의 흥미와 성취감, 자신감과 공동체 의식, 그리고 사고의 폭을 넓히는 계기를 갖게 되었다. 특히 자신감의 향상은 단순 기능 및 지식의 습득에서 벗어나 산업사회에서 요구되는 능력과 새로운 환경에 적응할 수 있는 능력을 길러주는데 효과적이다. 셋째, 산업현장과 관련된 보다 현장 중심적인 과제를 해결함으로써, 측량실기능력 향상뿐만 아니라 다양한 경험을 통하여 과제를 발견하고 해결하는 등 부가적인 능력 또한 신장되었다. 나아가 학생 스스로 자신의 생애와 학습에 대한 관심과 동기를 일으키고 새로운 지식과 기술이 급격하게 변화하는 직업세계에 적응할 수 있는 자질과 능력을 길러내는데 도움이 되었다. 넷째, 2012년부터 도입된 전문교과 성취평가제를 학습지도안 모형 구안에 적용하여, 보다 명료하고 객관화된 평가기준을 마련하였으며, 성취수준별 지도를 통해 개별적인 학습이 가능하도록 구상하였다. 이는 모둠별 협동학습의 단점을 보완하여 학습자 개인의 성취수준을 높이고, 일정 수준의 성취목표에 도달하는데 도움이 되었다.

• 대한관절경학회지
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• 제13권1호
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• pp.8-13
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• 2009

목적: 전방 십자 인대 재건술을 위해 동종 경골건을 이용하였고 대퇴 고정을 위해 $Endobutton^{(R)}$과 $Rigidfix^{(R)}$을 사용한 Hybrid 대퇴고정 그리고 경골 고정을 위해 $Retroscrew^{(R)}$ 및 추가 고정을 시행한 후 임상적 결과를 알아보고자 하였다. 대상 및 방법: 2004년 2월부터 2007년 2월까지 Hybrid 대퇴 고정과 $Retroscrew^{(R)}$를 이용한 전방 십자 인대 재건술을 시행하였고 1년 이상 추시(범위: 12~25개월) 가능 하였던 32명, 32례를 대상으로 하였다. 임상적 결과는 재건술 전후 Lysholm 슬관절 점수, IKDC 평가 기준, $Telos^{(R)}$ 전방 전위 검사를 이용하였고 최종 추시시 단순 방사선 전후면 및 측면 사진을 촬영하여 골 터널 확장 정도를 측정하였다. 결과: Lysholm 슬관절 점수는 술 전 평균 $67.9{\pm}5.4$점(범위: 51~77점)에서 최종 추시시 $94.1{\pm}6.8$점(범위: 68~98점)으로 유의하게 향상되었고(p<0.05) IKDC 최종 추시 평가상 정상(A) 22례(69%), 거의 정상(B) 9례(28%), 비정상(C) 1례(3%)로 심한 비정상(D)을 보이는 경우는 없었다. $Telos^{(R)}$ 스트레스 부하 방사선 검사상 건측과의 차이가 술 전 평균 $13.2\;mm{\pm}5.8$(범위: 6~21 mm)에서 술 후 평균 $3.4\;mm{\pm}2.8$(범위: 0~11 mm)로 유의하게 호전되었다(p<0.05). 골 터널 확장은 대퇴 터널은 전후면 사진상 18.7%, 측면 사진상 12.4%(p<0.05), 경골 터널은 전후면 사진상 9.6%, 측면 사진상 8.5%의 확장을 보였다(p<0.05). 그러나 골 터널 확장의 정도와 슬관절 기능 사이에는 통계학적 유의성을 보이지 않았다(p>0.05). 결론: 동종 경골건의 고정시 Hybrid 대퇴고정과 $Retroscrew^{(R)}$를 이용한 전방 십자 인대 재건술은 이식건의 해부학적 고정을 가능하게 하였고 임상적으로 우수한 결과를 보였다.

• 한국가축번식학회지
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• 제24권4호
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• pp.357-364
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• 2000

Members of the glycoprotein family, which includes CG, LH, FSH and TSH, comprise two noncovalently linked $\alpha$- and $\beta$-subunits. Equine chorionic gonadotropin (eCG), known as PMSG, has a number of interesting and unique characteristics since it appears to be a single molecule that possesses both LH- and FSH-like activities in other species than the horse. This dual activity of eCG in heterologous species is of fundamental interest to the study of the structure-function relationships of gonadotropins and their receptors. CG and LH $\beta$ genes are different in primates. In horse, however, a single gene encodes both eCG and eLH $\beta$ -subunits. The subunit mRNA levels seem to be independently regulated and their imbalance may account for differences in the quantities of $\alpha$ - and $\beta$-subunits in the placenta and pituitary. The dual activities of eCG could be separated by removal of the N-linked oligosaccharide on the $\alpha$-subunit Asn 56 or CTP-associated O-linked oligosaccharides. The tethered-eCG was efficiently secreted and showed similar LH-like activity to the dimeric eCG. Interestingly, the FSH-like activity of the tethered-eCG was increased markedly in comparison with the native and wild type eCG. These results also suggest that this molecular can implay particular models of FSH-like activity not LH-like activity in the eCG/indicate that the constructs of tethered molecule will be useful in the study of mutants that affect subunit association and/or secretion. A single-chain analog can also be constructed to include additional hormone-specific bioactive generating potentially efficacious compounds that have only FSH-like activity. The LH/CG receptor (LH/CGR), a membrane glycoprotein that is present on testicular Leydig cells and ovarian theca, granulosa, luteal, and interstitial cells, plays a pivotal role in the regulation of gonadal development and function in males as well as in nonpregnant and pregnant females. The LH/CGR is a member of the family of G protein-coupled receptors and its structure is predicted to of a large extracellular domain connected to a bundle of seven membrane-spanning a-helices. The LH/CGR phosphorylation can be induced with a phorbol ester, but not with a calcium ionophore. The truncated form of LHR also was down-regulated normally in response to hCG stimulation. In contrast, the cell lines expressing LHR-t631 or LHR-628, the two phosphorylation-negative receptor mutant, showed a delay in the early phase of hCG-induced desensitization, a complete loss of PMA-induced desensitization, and an increase in the rate of hCG-induced receptor down-regulation. These results clearly show that residues 632~653 in the C-terminal tail of the LHR are involved in PMA-induced desensitization, hCG-induced desensitization, and hCG-induced down-regulation. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty. Cells expressing LHR-D556Y bind hCG with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. This mutation enhances the internalization of the free and agoinst-occupied receptors ~2- and ~17- fold, respectively. We conclude that the state of activation of the LHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing LHR-L435R is due to the fast rate of internalization of the bound hCG. This statement is supported by the finding that hCG responsiveness is restored when the cells are lysed and signal transduction is measured in a subcellular fraction (membranes) that cannot internalize the bound hormone.

• Asia pacific journal of information systems
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• 제18권1호
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• pp.97-115
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• 2008

Introduction The e-government is concerned with using Internet and Web technologies to exchange information and services with citizens, businesses and other related organizations, and it centers on three functions, namely informational, interactive, and transactional [UN, 2001]. Many developed countries like the U.S. have been actively involved in e-government projects, since they enable both more effective public services for citizens and more efficient internal operations. Korea is among these leading countries that are planning to leverage computer and communication technologies to provide for integration of work processes and information as well as convenient access to information and services. For this reason, evaluating e-government projects is becoming a crucial issue for both researchers and policy-makers. However, most research to date has primarily focused on a model of success of an e-government system designed for citizens, overlooking internal systems specifically created for employees working in a public organization. This paper is intended to propose a model to measure the success of a Web-based information system designed for use by internal users at Chungwadae, the executive branch of Korea's central government. The paper is also aimed at applying the model to the assessment of the present system being used at Chungwadae in comparison with the preceding system. Evaluating an e-Government System The most widely cited model of information systems success today is that of DeLone and McLean[1992, 2003, 2004]. The original model states that the success of an information system can be measured using six dimensions, including system quality, information quality, use, user satisfaction, individual impact, and organizational impact. Although the ultimate success of an information system may be reflected in the impact that the system has upon individuals as well as an organization, aspects of using the system such as system use and user satisfaction can play an important role in determining the system success, because the system would be a sheer failure if users don't like and use the system. As a response to criticisms given by numerous researchers, the authors adapted their model to fit the emerging Web-based environment. The revised model[DeLone and McLean, 2003] they offered included an additional quality dimension, namely service quality, and combined individual and organizational impacts into net benefits which can also influence user satisfaction. The e-government system success model can be built around this updated model. Our model incorporates information quality, system quality, and service quality as in the DeLone and McLean model. However, the 'system use' dimension has been replaced by perceived usefulness, as suggested by Seddon[1998]. In addition, because the e-government systems that this paper focuses on are internal public systems used in government agencies, the 'net benefits' dimension has been replaced by perceived work efficiency. Based on the proposed model, a total of nine hypotheses have been formulated which we tested using an empirical analysis. Methods A questionnaire form has been created with items that are designed to examine the relationships among the variables in the model. The questionnaire has been handed over, in person, to 65 members of Chungwadae staff who are now actively using the E-Support System, the present information system created to support internal work at Chungwadae. We made arrangements to meet with each individual who agreed to participate in our survey, and helped to fill out the survey form with explanations. Of the 65 copies that were delivered, only 33 were returned, and 30 responses of these have been adopted for our analysis, since three were not valid. The extremely small sample size was due to the limited number of staff members who had adequate experience required of this study. Results We gathered data from the questionnaire survey and analyzed them using a regression analysis to test the hypotheses. As shown in the table below, the results indicated that all three dimensions of an information system’s quality are positively related to user satisfaction. However, information quality and system quality were found to be positively related to perceived usefulness, while service quality was not. In addition, perceived usefulness is not positively related to user satisfaction, implying that a user may find a system useful, but may not be satisfied with it. Finally, user satisfaction and perceived usefulness both are positively related to perceived work efficiency. This suggests that workers' positive experience with the system is important to guarantee favorable work efficiency. Conclusions We conclude that the proposed model proved useful in measuring the success of an internal information system used by a government agency. To demonstrate the applicability and usefulness of the model in the paper, we applied the model to the assessment of the present internal system used at Chungwadae in comparison with the preceding system. The results showed that the present system outperforms the preceding one in a statistically significant way. Future research will have to focus on applying the model to Korea's governmental agencies other than Chungwadae and examine whether it proves applicable in different types of governmental organizations.