• 한국정보통신학회논문지
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• 제9권4호
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• pp.753-757
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• 2005

무선랜은 유선랜의 대안으로 개발되어 설비의 용이성으로 인하여 특수분야와 특수용도로만 이용되어오다가 최근 들어 그 표준과 기술이 급속도로 발전하여 현재는 건물간의 중계회선 또는 광범위의 유저들을 위한 일대일 통신등의 수단과 고속인터넷의 중계회선, 그리고 멀티미디어 대폭을 요구하는 화상통신의 수단으로 이용되고 있다. 개발당시 10Mbps의 전송속도에서 시작하여 최근에는 100Mbps 대역까지 확장되어가고 있는 추세이다. 특히 캠퍼스 무선랜의 경우 인터넷 중계회선으로서 체감적으로 차이는 있지만 최소 10Mbps속도로 반경 $100\~200m$ 범위를 보장하여야한다고 사료된다. 본 논문에서는 실제이용환경에서 무선랜이 인터넷 중계회선으로서의 효용성입증을 위하여 측정하였다. 측정한 결과 IEEE802.11b 를 기반으로 네트워크를 구성하는 경우 최소 3개 이상의 AP로서 구성하여야한다는 것을 입증하였다. 향후 해양환경에서의 무선랜의 성능평가를 수행함에 그 목적이 있다.

• 사물인터넷융복합논문지
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• 제6권3호
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• pp.59-65
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• 2020

일상에서 이용하는 모든 물건들이 네트워크 접속 기능을 갖추고, 이들이 긴밀하게 연동하면서 생활 및 업무의 편의성을 높이는 IoT(사물인터넷) 시대가 활짝 열렸다. 로봇도 IoT 환경에 맞춰 발전해야 하는 상황이다. 논문에서는 IoT 환경을 위한 다리가 있는 로봇 궤적을 생성하기 위해 새로운 형태의 EFM (진화 퍼지 머신)을 사용하는 방법에 대하여 다룬다. 퍼지 시스템은 비선형 시스템을 묘사하는 데 널리 사용되고 있다. 퍼지 시스템에서 퍼지 모델의 전반부 및 후반부 구조를 결정하는 것은 매우 중요한 문제이다. EFM은 다리가 달린 로봇을 위해 퍼지 시스템의 전반부 및 후반부 구조를 진화시켜 효율적으로 구조를 개선한다. 퍼지 시스템에서 각 구조의 로봇 궤적 매개 변수를 생성하고 EFM에 의해 자동으로 조정된다. 제안된 접근 방식은 다리가 있는 로봇에 적용하여 성능을 살펴본다.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.151-158
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• 2010

국내/외 산업기반시설들은 악의적인 사용자로부터 받은 공격으로 인해 큰 피해를 받고 있다. 특히, 전력, 댐, 철도, 원자력 등과 같은 국가 주요핵심기반시설이 피해를 입었을 경우 그 피해는 경제적인 문제뿐만 아니라, 국민의 생명과도 직결될 수 있다. 이러한 국가 주요핵심기반시설은 Modbus RS485통신을 사용하는 SCADA 시스템으로 구성되어 있는 것이 일반적이며, 이러한 특성상 SCADA 시스템에서 직접 명령을 전달하는 RTU Master와 Slave는 RJ11 케이블로 연결되어 있다. RJ11 케이블의 전송 범위는 1km정도로 대역이 넓기 때문에 케이블에 물리적인 접속을 통하여 데이터 스푸핑이 가능하다. 따라서 본 논문에서는 최근 보안 중요성이 대두되고 있는 국가 주요핵심기반시설 내의 SCADA 시스템 보안 향상을 위하여 데이터 스푸핑 탐지를 위한 유휴 시간 측정 시스템을 설계하였다.

• Toxicological Research
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• 제6권2호
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• pp.159-166
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• 1990

The ability of many toxigenic fungi to invade and develop in a wide variety of raw ingredients of human diet renders human exposure to mycotoxing very difficult to avoid. Most of the energy-rich commodities, such as cereal grains, oil seeds, tree nuts, and dehydrated fruits, are susceptible to mycotoxin contamination. Mycotoxins therefare have been recognized as an important class of hazardous substances in the human food chain. Although human exposure to mycotoxins is largely through ingestion, inhalation and skin contact may also be significant under conditions other than consumption of foods. Human ingestion of mycotoxins is due to consumption of contaminated dietary ingredients and the edible tissues and products of domestic animals that have been exposed to mycotoxins in moldy feed. Large scale acute human mycotoxicoses, such as ergotism in France, alimentary toxic aleukia in Russia, yellow rice syndrome in Japan, endemic nephropathy in Balkan countries, and acute aflatoxin poisonings in India and Taiwan, have been well documented, indicating that mycotoxicosis is a global problem. In some incidents, hundreds of victims were killed and many more became seriously ill. The mycotoxins that have been implicated in the etiology of these human diseases include aflatoxins, citreoviridin, cyclopiazonic acid, ergot alkaloids, moniliformin, ochratoxin A, trichothecenes, tenuazonic acid, and zearalenone. Among these, aflatoxins have been also implicated in the etiology of human primary liver cancer in those high-incidence countries in Africa and southeast Asia. It is well recognized that cause-effect relationship between mycotoxins and human diseases is very difficult to establish, especially for the cancer connection. Careful risk assessment must be performed to determine whether a mycotoxin indeed warrants costly regulatory actions.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1993년도 제2회 신약개발 연구발표회 초록집
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• pp.71-71
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• 1993

Carboxylesterase is widely distributed in the tissues of vertebrates, insects, plants and mycobacteria. Among various tissues of animals and humans, the highest esterase activity with various substrates is found in the liver. Kidney has moderate carboxylesterase activity in the proximal tubules. Considerable esterase activity is also found in the small intestine epithet elial cells and serum of mammals. Besides these tissues, carboxylesterase has been found in the lung, testis, adipose tissue, nasal mucosa and even in the central nervous system. Hepatic microsomal carboxylesterase catalyzes the hydrolysis of a wide variety of endogenous and exogenous compounds such as carboxylester, thioester and aromatic amide. Since carboxylesterases are important for metabolic activation of prodrugs and detoxification of xenobiotics, differences in substrate specificity and immunological properties of this enzyme are important in connection with choosing a suitable laboratory animal for the evaluation of biotransformation and toxicity of drugs. On the other hand, liver, kidney, intestine and serum were found to contain multiple forms of carboxylesterases in animal species and humans. In fact, we have purified more than fifteen isoforms of carboxylesterases from microsomes of liver, kidney and intestinal mucosa of nine animal species and humans. and characteristics of these isoforms were compared each other in terms of their physical and immunochemical properties. On the other hand, we have reported that hepatic microsomal carboxylesterases are induced by many exogenous compounds such as phenobarbital, polycyclic aromatic hydrocarbons, Aroclor 1254, aminopyrine and clofibrate. Later, we showed that some isoforms of hepatic carboxylesterase were induced by glucocorticoids such as dexamethasone and 16 ${\alpha}$-carbonitrile, but other isoforms were rather inhibited by these compounds. These findings indicate that involvement of carboxylesterases in the metabolism and toxicity of drugs should be explained by the isoforms involved. Since 1991, we have carried out detailed research investigating the types of carboxylesterases involved in the metabolic activation of CPT-11, a derivative of camptothecin, to the active metabolite, SN-38. The results obtained strongly suggest that some isoforms of carboxylesterase of liver microsomes and intestinal mucosal membrane are exclusively involved in CPT-11 metabolism. In this symposium, the properties of carboxylesterase isoforms purified from liver, kidney and intestine of animal species and humans are outlined. In addition, metabolism of CPT-11, a novel antitumor agent, by carboxylesterases in relation to the effectiveness will also be discussed.

• 한국치위생학회지
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• 제8권4호
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• pp.193-204
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• 2008

Purpose : The purpose of this study was to make a comparative analysis of the curriculum segment of the dental hygiene education accrediting criteria, one of the six segments of the criteria, and the curriculums of 26 colleges in a bid to provide information on the modification or improvement of the curriculums. Method : The curriculums of 18 three-year-course colleges and eight four-year-course universities were selected, and the courses offered by 10 colleges or more were categorized into three different fields to tabulate the courses: primary education, prevention / education, and clinical dental hygiene. After the courses were analyzed, some of them that were possible to integrate in view of dental hygienist duties were presented in this study as inclusive courses. Results : There was connection among the degree courses of the three-year-course curriculums in the field of primary education. The curriculums failed to keep up with the worldwide globalization trend. 90 credits or more were allocated to major subjects, which satisfied one of the mandatory requirements of the accrediting criteria, and two colleges provided theoretical and practical courses in the ratio of 50:50. A wide variety of personality-education and teaching-profession courses were offered according to each college's circumstances. None of the colleges was equipped with an inclusive curriculum, and there was a tendency for the three-year-course colleges to offer segmented subjects in accordance with the national examination. The courses in the field of prevention and education that are bound up with the job performance of dental hygienists should be integrated into dental hygiene and practice, and the courses in the clinical dental hygiene field should be incorporated into an inclusive course of 치과임상학. The integration of the courses will make it possible to ensure the successful articulation of the different school systems and to stay abreast with the globalization trend. Even just inclusive courses should give more weight to practice than theory to bolster the job performance of dental hygienists, and an inclusive curriculum should be prepared for students to receive activity-centered hands-on education in different semesters.

• 디자인학연구
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• 제16권1호
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• pp.117-126
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• 2003

인간과 컴퓨터의 상호작용은 컴퓨터의 기술적 발달과 함께 다양하게 변화하여 왔으며 웹의 보편화와 함께 웹의 특성을 반영한 다양한 형식과 방법의 상호작용이 시도되고 있다. 이러한 다양한 상호작용의 개념중 대화형 에이전트는 대화의 대상으로 캐릭터를 사용하며 대화에 의한 상호작용을 통해 자연스럽고 인간적이며 직관적인 상호작용을 제시하고 있다. 그러나 현재까지의 연구는 그 구현을 중심으로 진행되고 있으며 웹에서의 실질적인 적용은 시험적 단계를 거치고 있다. 따라서 본 연구에서는 가상 강좌 사이트에서 보다 적극적인 활용대상으로서 대화형 에이전트를 적용하기 위해 대화형 에이전트의 상호작용 방식의 주요 개념인 대화에 대하여 고찰하였다. 다음으로 웹에서 이루어지는 대화적 특성을 연구하고 웹에서의 대화 구성 방식을 도출하였다. 이를 바탕으로 대화형 에이전트를 구현하여 가상 강좌 사이트에 적용하였으며 사이트 운영 및 평가를 통해 대화형 에이전트의 적용 가능성을 살펴보았다.

• 센서학회지
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• 제11권1호
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• pp.1-8
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• 2002

온도 측정이 필요한 다양한 용도의 소자에 응용되고 있는 열전쌍열(thermopile) 제작에 SOI 구조를 응용하여, 특성을 개선하였다. 열전쌍열을 구성하는 저항체가 단결정 실리콘으로, 제벡 계수(seebeck coefficient)가 높은 재료일 뿐 아니라, 실리콘 저항체를 산화막을 이용하여 실리콘 기판과 절연 분리한 구조로 되어있어서, 기존의 이온주입 공정에 의해 불순물을 주입하는 방법으로 제작된 저항체에 비해서 두 접점(hot junction 및 cold junction) 사이의 열 전달을 극적으로 감소시킬 수 있어서 소자의 특성을 개선할 수 있었다. 열전쌍열은 p형 단결정 실리콘 저항체 17개 및 n형 17개를 직렬 연결로 구성했다. 저항체의 길이 $1600{\mu}m$, 폭 $40{\mu}m$, 두께 $1{\mu}m$으로 제작된 열전쌍열에 빛을 조사하여 소자 양단에 온도차를 발생시키고, 그 때 발생하는 기전력을 측정한 결과 130mV/K의 우수한 특성을 나타냈다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권3호
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• pp.170-175
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• 2009

Purpose : The purpose of this study is to evaluate 7-year survival rate of implants placed without bone graft in posterior maxilla and compare the survival rate by the age and gender of patient, length and diameter of implant, region of implant placement, bicortical engagement of fixture, and connection of prosthesis. Material and methods : 78 patients (170 implants) who visited our institution from 2002 to 2007 and were followed up with panoramic view and medical records. Kaplan-Meier survival analysis and Log Rank (Mantel-Cox) test were used. Results and conclusions : A 7-year cumulative survival rate for implants placed in posterior maxilla without sinus graft was 95.3%. The survival rate in men was 91.8%, significantly lower than 98.8% in woman.(p<0.05). However, the survival rate by the length of the implants did not show any significant differences.(p>0.05), while the wide platform implant resulted in 85% survival rate which was statistically lower than 98.5% in regular platform. The posterior maxillary implants engaged bicortically showed 97.6% of 7-year Survival rate, comparing 88.6% in not engaged implants. The survival rate of the single implant was 91.2%, while 98.5% in splinted prosthesis. Therefore, the bicortical engagement of the fixtures and splinted prosthesis may be recommended to get a long-term survival rate in posterior maxilla.

• The Journal of Advanced Prosthodontics
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• 제8권4호
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• pp.304-312
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• 2016

PURPOSE. The aim of this study was to investigate the stress distribution of 2-short implants (2SIs) installed in a severely atrophic maxillary molar site. MATERIALS AND METHODS. Three different diameters of internal connection implants were modeled: narrow platform (NP), regular platform (RP), and wide platform (WP). The maxillary first molars were restored with one implant or two short implants. Three 2SI models (NP-oblique, NP-vertical, and NP-horizontal) and four single implant models (RP and WP in a centered or cantilevered position) were used. Axial and oblique loadings were applied on the occlusal surface of the crown. The von Mises stress values were measured at the bone-implant, peri-implant bone, and implant/abutment complex. RESULTS. The highest stress distribution at the bone-implant interface and the peri-implant bone was noticed in the RP group, and the lowest stress distribution was observed in the 2SI groups. Cantilevered position showed unfavorable stress distribution with axial loading. 2SI types did not affect the stress distribution in oblique loading. The number and installation positions of the implant, rather than the bone level, influenced the stress distribution of 2SIs. The implant/abutment complex of WP presented the highest stress concentration while that of 2SIs showed the lowest stress concentration. CONCLUSION. 2SIs may be useful for achieving stable stress distribution on the surrounding bone and implant-abutment complex in the atrophic posterior maxilla.