The semiconductor and display industries require the development of plasma resistant materials for use in high density plasma etching process equipment. Yttria (Y2O3) is a ceramic material mainly used to ensure good plasma resistance properties, which requires a dense microstructure. In commercial production, a sintering process is applied to reduce the sintering temperature of Y2O3. In this study, the effect of the addition of glass frit to the sintered specimen was examined when manufacturing yttria sintered specimens for semiconductor process equipment parts. The Y2O3 specimen was shaped into a Ø50 mm size and then sintered at 1,600 °C for 1~8 h. The characteristics, X-ray diffraction pattern, densities, contraction rate of the specimen, and swelling of the surface of the Y2O3 specimens were investigated as a function of the sintering time and glass frit addition. The Y2O3 specimen exhibited a density of over 4.9 g/cm3 as the sintering time increased, and the swelling phenomenon characteristics were improved by glass frit, by controlling particle size.

In this study, the glass melting properties are evaluated to examine the possibility of using refused coal ore as replacement for ceramic materials. To fabricate the glass, refused coal ore with calcium carbonate and sodium carbonate in it (which are added as supplementary materials) is put into an alumina crucible, melted at 1,200 ~ 1,500℃ for 1 hr, and then annealed at 600℃ for 2 hrs. We fabricate a black colored glass. The properties of the glass are measured by XRD (X-ray diffractometry) and TG-DTA (thermogravimetry-differential thermal analysis). Glass samples manufactured at more than 1,300℃ with more than 60 % of refused coal ore are found by XRD to be non-crystalline in nature. In the case of the glass sample with 40 % of refused coal ore, from the sample melted at 1,200℃, a sodium aluminum phosphate peak, a disodium calcium silicate peak, and an unknown peak are observed. On the other hand, in the sample melted at 1,300℃, only the sodium aluminum phosphate peak and unknown peak are observed. And, peak changes that affect crystallization of the glass according to melting temperature are found. Therefore, it is concluded that glass with refused coal ore has good melting conditions at more than 1,200℃ and so can be applied to the construction field for materials such as glass tile, foamed glass panels, etc.

In this study, glass fibers are fabricated via a continuous spinning process using manganese slag, steel slag, and silica stone. To fabricate the glass fibers, raw materials are put into an alumina crucible, melted at 1550℃ for 2 hrs, and then annealed at 600℃ for 2 hrs. We obtain a black colored glass. We identify the non-crystalline nature of the glass using an XRD(x-ray diffractometer) graph. An adaptable temperature for spinning of the bulk marble glass is characterized using a high temperature viscometer. Spinning is carried out using direct melting spinning equipment as a function of the fiberizing temperature in the range of 1109℃ to 1166℃ , while the winder speed is in the range of 100rpm to 250rpm. We investigate the various properties of glass fibers. The average diameters of the glass fibers are measured by optical microscope and FE-SEM. The average diameter of the glass fibers is 73 μm at 100rpm, 65 μm at 150rpm, 55 μm at 200rpm, and 45 μm at 250rpm. The mechanical properties of the fibers are confirmed using a UTM(Universal materials testing machine). The average tensile strength of the glass fibers is 21MPa at 100rpm, 31MPa at 150rpm, 34MPa at 200rpm, and 45MPa at 250rpm.

This paper considers a paternity and kinship analysis system(PKAS) being currently used in real sites. A knowledge-based expert system is proposed to improve the performance of PKAS in terms of accuracy, speed, training time, and satisfaction, which are common measures for evaluation. The knowledge base, one of the most important components in the knowledge-based expert system(KBES), consists of a rule made from random matching algorithm, decision rules of allele types and guide rules of options. The last two rules are learning incrementally from sample data. The results show that PKAS armed with the expert system ensures the better performance with regard to these criteria than the existing system. Especially as far as speed is concerned, as the sample size increases, it outperforms the existing one. As the number of samples increases, while processing time increases nearly exponentially in the existing PKAS, it does linearly in our proposed system.

This study is aimed to investigate the association between anaerobic․aerobic exercise intensity and hand steadiness. Hand steadiness is the decisive contributor to affecting the job performance just as in the rifle shooting and archery in sports and the microscope-related jobs requiring hand steadiness in industries. In anaerobic exercise condition hand steadiness is measured through hand steadiness tester having 9 different diameter holes after each subject exerts 25%, 50%, 75%, and 100% of maximum back strength. In aerobic exercise occasion it is evaluated at each time heart rate reaches 115%, 130%, and 145% of reference heart rate measured in no task condition after they do jumping jack. The results indicate that an increased intensity in both types of exercise reduces hand steadiness, but hand steadiness at 25% of maximum back strength and 115% of reference heart rate is rather greater than at no exercise. Just as the relation between cognitive stress and job performance has upside-down U form, so does the association of physical loading to hand steadiness, which means that a little exercise tends to improve hand steadiness in comparison with no exercise.

The objective of this study is to investigate the relationship between anaerobic・aerobic exercise intensity and hand steadiness. Based on physiological analysis the conceptual model explaining that both increased anaerobic and aerobic exercise intensity reduce hand steadiness is suggested, which is verified through the experiment with 20 subjects. Hand steadiness is the critical contributor to having an effect on the job performance just as in the rifle shooting and archery in sports, and the microscope-related job requiring hand steadiness in industries, and so forth. In anaerobic exercise experiment the hand steadiness is measured through hand steadiness tester having 9 different diameter holes after each subject exerts 25%, 50%, 75%, and 100% of maximum back strength measured by back muscle dynamometer. In aerobic exercise condition after they do jumping jack, it is evaluated at each time heart rate reaches 115%, 130%, and 145% of reference heart rate measured in no exercise. The findings are that an increased intensity in both types of exercises tend to decrease hand steadiness, but hand steadiness at 25% of maximum back strength and 115% of reference heart rate is rather higher than at no exercise. Just as the association between cognitive stress and job performance has upside-down U form, so does the relation of physical loading to hand steadiness, which means that a little exercise has a tendency to improve hand steadiness compared to one in no exercise condition .

The purpose of this paper is to suggest the strategical lifting postures able to alleviate imbalanced EMG amplitude leading to an increase in low back muscle fatigue while lifting asymmetric load dynamically. Eleven male subjects are required to lift symm

This study is aimed to show that an asymmetric load in the frontal plane leads to an increase in low back loading and fatigue in comparison with a symmetric load when workers lift an external weight by investigating previous studies and verifying the phen

The goal of this study is to suggest the conceptual model explaining the mechanism that an asymmetric load elevates low back pain(LBP). The model suggested shows that an asymmetric load in the frontal plane leads to unbalanced hand load, which affects the difference between right and left EMG amplitude on the pairwise back muscles and the increase in muscle fatigue compared with a symmetric load. The model is verified by an experiment that ten male subjects are required to lift and hold at waist height each symmetric and asymmetric load, then the EMG data collected is analyzed concentrating on median frequency used as one muscle fatigue index. The results show that muscle fatigue in lifting an asymmetric load is significantly more than in doing a symmetric load in both low and high load weights. The results means that the movement of load center of gravity(LCG) within a box handled can be one factor elevating LBP, that condition should be controlled by administrative or engineering interventions if possible.

전문가시스템의 성공을 좌우하는 지식추출은 주요 애로공정 중의 하나로 알려져 있다. 설상가상으로 전문가의 부재, 새로운 또는 복잡한 문제 등 영역의 특성상 전문가시스템 개발은 실패할 수 있다. 이러한 문제점을 극복하기 위하여 본 논문에서는 KACE 구조를 제안하였다. 본 구조는 작업 발생기, 작업 실행기, 작업 평가기, 규칙 발생기와 전문가시스템 등 5개의 주요 요소로 구성되어 있다. 이 구조를 이용하여 NP-complete인 일정계획 문제에 대한 전문가

전문가시스템의 성공을 좌우하는 지식추출은 주요 애로공정 중의 하나로 알려져 있다. 설상가상으로 전문가의 부재, 새로운 또는 복잡한 문제 등 영역의 특성상 전문가시스템 개발은 실패할 수 있다. 이러한 문제점을 극복하기 위하여 본 논문에서는 KACE구조를 제안하였다. 본 구조는 작업 발생기, 작업 실행기, 작업 평가기, 규칙 발생기와 전문가시스템 등 5개의 주요 요소로 구성되어 있다. 이 구조를 이용하여 NP-complete인 일정계획 문제에 대한 전문가시스템이 어떻게 구축될 수 있는가를 예시하였다.

본 연구는 소 배반포의 내부 세포괴로부터 다능성(pluripotency)을 지닌 배아 줄기 세포(embryonic stem cell) 또는 그 유사 세포를 분리 및 배양함으로써 줄기 세포 관련 분야의 기반 기술을 확립하고자 하였다. 소 체외수정란을 10～12일간 체외배양하여 생산된 부화 배반포를 세포분열이 불활성화된 생쥐 태아 섬유아 세포(mouse embryonic fibroblast, MEF) 위에서 배양하여 콜로니 형성을 유도하였으며, 이들로부터 내부 세포괴 유래의 형태를 지닌 것만을 광학현미경 하에서 물리적으로 분리하여 약 5～7일 간격으로 계대배양을 실시하였다. 이러한 방법을 통하여 배아 줄기 유사 세포의 특성을 40계대 이상 유지하는 2개의 세포주를 확립하였다. 각각의 세포주들은 높은 alkaline phosphatase(AP) 활성을 지니고 있었으며, 형광 면역 염색법과 PCR 기법을 사용하여 Oct-4, Nanog, STAT3, SSEA3 및 SSEA4의 발현을 관찰할 수 있었다. 이러한 결과를 종합하여 볼 때 ,본 연구에서는 소 배반포로부터 배아 줄기 세포주를 확립하는 제반 기술이 확립되었다고 판단되며, 향후 관련 분야 연구에 활용될 수 있을 것으로 기대된다.

Expert systems are popular ways to solve very complex and hard problems. However, it is well-known that knowledge acquisition is a bottleneck process to develop them. Furthermore, the development of the systems can fail because there is no expert or an expert less qualified. In order to overcome the problems that they possess, this thesis focuses on an extended architecture of the expert systems. A simulator and an induction system are added to the existing architecture of expert systems. An expert system for schedule-based material requirements planning(SBMRP) has been implemented to show how the extended architecture works, and produces better results than existing SBMRP systems.

The main purpose of this study is to identify the factors that affect purchase intention in B2C cooperative buying. The purchase intention is described in terms of participation frequency and total sum of purchasing on cooperative buying. It is very interesting that the influencing factors are not identical when two dependent variables. participation frequency and total sum of purchasing, are used. Residential area, sex, and product variability were selected as key influencing factors for the former case. On the other hand, residential area, price, and product quality were selected as key influencing factors for the latter case. Finally, it is worth while to stress that online community, one of the factors considered, will be a key factor as market of cooperative buying is getting bigger.

인터넷이 현대사회의 많은 부분을 대체해 감에 따라서 Off-line에서 이루어지던 중고자동차의 매매 역시 On-line에서의 매매가 활발해 지고 있다. 이러한 On-Line에서의 장점은 매매차량등록의 편의성과 지역적 제약을 받지 않는다는 점 등을 들 수 있으며, 이로 인하여 빠른 거래가 성사될 수 있다. 또한 매매상사의 중간마진을 없앰으로써 거래당사자간의 상호이익도 극대화될 수 있다. 반면에 객관적인 검사를 통한 신뢰성의 결여, 이로 인한 적정가격 산출의 어려움, 구매희망자와의 잦은 상담 가능성 등의 단점을 들 수 있다. 본 연구에서는 On-line 거래의 이러한 문제점을 해결하기 위하여 데이터마이닝 기법을 다룬다. 이 데이터마이닝 기법은 의사결정나무와 다중회귀분석을 포함하며, 각각 E-miner와 Statgraphics를 이용하여 분석되었다. E-miner를 활용한 의사결정나무를 도출하기 위하여 DATA의 전처리과정에 따른 비교분석이 수행되었으며, DATA는 학습용과 평가용으로 구분하여 이용되었다. 학습용 DATA에 기반하여 두 가지 기법에 대한 지식과 모델이 각각 도출되었으며, 이들 각각에 대한 비교평가가 이루어졌다. 또한 평가용 DATA에 대하여도 각각의 비교평가가 이루어졌으며. 이에 기초하여 보다 나은 On-line 매매지원시스템이 결정되었다.

Gene delivery is one of the keen interests in animal industry as well as research on gene functions. Some of the in vivo gene delivery techniques have been successively used in various tissues for the gene therapy and transgenesis. Despite intensive efforts, it still remains to overcome problems of limited local and regional administration and low transgene expression. To improve the efficiency of gene delivery, a new procedure was tested. We injected exogenous DNA containing LacZ into the female or male gonads and then pulsed electric field. Electroporated gonads showed positive X-gal staining in many seminiferous tubules of the porcine fetal gonads. Exogenously introduced LacZ genes were also expressed in female porcine gonad. In addition, we demonstrated efficient gene delivery in gonad of adult mouse. Furthermore, we succeed to generate genetically modified germline cells showing GFP and positive X-gal signals. The results suggest that the newly developed gene delivery is an effective way of in vivo transfection in mammals. The developed gene delivery procedure should be useful in producing transgenic animals when combined with primary cell culture and nuclear transplantation.

Task description is essential in performing task analysis which is required for designing man-machine systems. Currently, there are many methods to support the task description which is very complex and time-consuming. However, these methods contain some problems such as being hard to understand and a lack of description. This research deals with an object-oriented task description(OOTD) method trying to solve these problems effectively. The OOTD method includes an object-oriented task structure diagram and an object-oriented task attribute diagram. The former shows some relationship between a task and a derived task. The latter includes important attributes to define each task.