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방전플라즈마 소결법을 이용한 고밀도 탄화 붕소 제조 및 기계적 특성
김경훈,채재홍,박주석,김대근,심광보,Kim, Kyoung-Hun,Chae, Jae-Hong,Park, Joo-Seok,Kim, Dae-Keun,Shim, Kwang-Bo 한국결정성장학회 2007 한국결정성장학회지 Vol.17 No.3
방전플라즈마 소결법을 적용하여 탄화붕소 세라믹스를 제조하여 그 소결 특성, 미세 구조 및 기계적 특성을 평가하였다. 탄화붕소의 소결에 방전플라즈마 소결법을 적용하여 소결 조제의 첨가 없이 전통적인 소결법보다 낮은 온도에서 99% 이상의 완전 치밀화된 소결체를 제작할 수 있었으며, 탄화붕소 분말의 메탄을 세척을 통하여 분말 표면에 형성되어 있는 $B_2O_3$ 상을 사전에 제거함으로써 결정립의 조대화를 방지하여 균일한 미세구조의 형성을 유도할 수 있었으며 결과적으로 탄화붕소 소결체의 기계적 특성을 향상시킬 수 있었다. 특히 파괴인성의 경우 메탄을 세척을 통하여 30% 이상의 물성 향상을 달성하였다. [ $B_4C$ ] ceramics were fabricated by spark plasma sintering process and their sintering behavior, microstructure and mechanical properties were evaluated. Relative density of $B_4C$ ceramics were obtained by spark plasma sintering method reached as high as 99% at lower temperature than conventional sintering method, in addition, without any sintering additives. The mechanical properties of $B_4C$ ceramics was improved by a methanol washing process which can be removed $B_2O_3$ phase from a $B_4C$ powder surface. This improvement results ken the formation of homogeneous microstructure because the grain coarsening was suppressed by the elimination of $B_2O_3$ phase. Particularly, fracture toughness of the sintered specimen using a methanol washed powder improved over 30% compared with the specimen using an as-received commercial powder.
방전플라즈마 소결법에 의한 탄화 붕소 세라믹스의 소결 거동 및 기계적 특성
김경훈,채재홍,박주석,김대근,심광보,이병하,Kim, Kyoung-Hun,Chae, Jae-Hong,Park, Joo-Seok,Kim, Dae-Keun,Shim, Kwang-Bo,Lee, Byung-Ha 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.1
[ $B_4C$ ] ceramics were fabricated by spark plasma sintering process and their sintering behavior, microstructure and mechanical properties were evaluated. Relative density of $B_4C$ ceramics could be achieved by spark plasma sintering method reached as high as 99% at lower temperature than conventional sintering method, in addition, without any sintering additives. The mechanical properties of $B_4C$ ceramics could be improved by the heat treatment at $1300^{\circ}C$ during sintering process which can be removed $B_2O_3$ phase from a $B_4C$ powder surface. This improvement results from the formation of a fine and homogeneous microstructure because the grain coarsening was suppressed by the elimination of $B_2O_3$ phase. Particularly, mechanical properties of the specimen experienced the $B_2O_3$ removing process improved over 30% compared with the specimen without that process.
컷팅 방향이 전방십자인대 손상 위험 요인에 미치는 영향
김경훈(Kyoung Hun Kim),조준행(Joon Haeng Cho) 한국사회체육학회 2012 한국사회체육학회지 Vol.0 No.48
The purpose of this study was to identify the effects of cutting direction on the ACL injury mechanism during cutting. Eighteen subjects who has the right leg dominant were participated in this study. We used vicon and force platform. The results were as follows. First, 90°cutting showed larger joint range of motion than 0 and 45° in sagittal and frontal plane. Second, 45 and 90°degree cutting showed increased moment compared to 0° cutting in extension. And tibia external rotation moment showed in sequence(0°< 45°< 90°). Third, 45 and 90° cutting showed increased absorption power compared to 0°. Finally, 90° cutting showed larger than 0°in anterior shear force. The finding of this study support as the cutting direction larger there was greater risk of ACL injury in knee joint. Therefore, we think it is necessary to train the athlete about this during training season.
네트워크 분석 기법을 이용한 운동처방 관리시스템 설계 및 구현
김경훈(Kyoung-Hun Kim),송영재(Young-Jae Song) 한국콘텐츠학회 2011 한국콘텐츠학회논문지 Vol.11 No.12
운동이 신체적, 정신적 건강에 긍정적인 영향을 미친다는 것은 수많은 연구를 통해 일반적인 상식이 되었다. 그리고 규칙적인 운동은 체지방 감소와 혈중지질을 감소시켜 비만을 조절하며, 궁극적으로 인간의 삶의 질을 향상시킨다고 보고되어 있다. 본 연구에서는 선행연구를 통해 수영운동치료 관리를 위한 지표들을 도출하였으며, Fuzzy ANP(Analytic Network Process) 기법을 이용하여 지표들간의 상관관계를 모델링하여 가중치를 측정하였다. 측정된 결과를 가지고, 공간 제약 없이 개인별 맞춤 운동처방을 실시간으로 알려주도록 설계 하였다. 그리고 휴대폰, 스마트폰, 노트북 등 모바일 장치를 통해 실시간으로 질환자별 맞춤관리가 이루어질 수 있도록 환자관리시스템을 구현하고자 한다. It has become general common sense through numerous researches that exercise provides positive impacts on physical and mental health. And it has been reported that regular exercise adjusts obesity by reducing body fat and lipid levels found in the blood and ultimately, it improves human quality of life. In this study, indices for managing swimming exercise therapy were induced through prior researches and weighted value was measured by modelling correlations between indices by using fuzzy ANP (Analytic Network Process) technique. With the determined results, users can be provided with real-time individualized exercise prescription without space constraint. And patient management system was intended to be realized so that tailor-made management per patient can be established on real-time through mobile equipments such as portable phone, smart phone, notebook and etc.
착지 시 성별과 높이에 따른 무릎 움직임과 각속도의 3차원적 비교 분석
김경훈(Kyoung Hun Kim),고영철(Young Chul Koh),조준행(Joon Haeng Cho) 한국사회체육학회 2012 한국사회체육학회지 Vol.0 No.49
The purpose of this study was to analyse knee movement and angular veloctiy with gender differences and landing height during landing. In this study, 24 participants(12 males, 12 females) dropped from a height of 30cm and 60cm. 8 vicon cameras and 1 force plate were used to anlayze the kinematic data. The results are followings: Females tended to contact the ground in a more knee extended position. Female also exhibited increased valgus and tibia internal rotation at Initial contact and PVGRF time at higher landing height. Third, Female exhibited increased maximum valgus, tibia internal rotation and maximum angular velocities with increased landing height compared to males. The results of this study showed that female might be predisposed to higher incidence of knee injury during landing. Gluteus medius and quadriceps strengthening program can be a important part to prevent injuries and consideration of these strengthening program is needed in sports activities.
김경훈(Kyoung Hun Kim),조준행(Joon Haeng Cho) 한국사회체육학회 2011 한국사회체육학회지 Vol.0 No.44
Relationship between Functional Ankle Instability and Landing Pattern. Korean Journal of Sport Biomechanics, Vol. 00, No. 0, pp. 00-00, 2010. Functional ankle instability(FAI) usually appears after ankle sprain. But differences in landing patterns between stable ankle(SA) and FAI have not been determined. The purpose of this study was to compare differences in landing patterns with subject who has FAI and SA during drop landing. Through this study, we came to the conclusion that FAI affects on the movements of lower extremities and ground reaction force during drop landing from following results. First, when compared with SA, FAI group showed decreased maximal knee flexion(MKF) in sagittal plane of ankle, and increased inversion at initial contact(IC) and decreased inversion at MKF in frontal plane of the ankle. Second, FAI group showed decreased flexion at MKF and increased valgus at IC in frontal plane of the knee. Third, subjects with FAI showed increased flexion at IC in sagittal plane, decreased abduction at IC and increased adduction at MKF in hip. FAI group appeared to have higher GRF in all directions except posterior and lateral side of the ankle. Finally, FAI group showed higher medial-lateral excusion in COP. However, FAI group appeared to have lower power absorption in the ankle and the knee. Therefore, it is necessary to develop appropriate treatment paradigms for ankle sprain before FAI develops.
변경관리에서 ANP기법을 이용한 컴포넌트 선택 결정 방법
김경훈(Kyoung-Hun Kim),송영재(Young-Jae Song) 한국콘텐츠학회 2012 한국콘텐츠학회논문지 Vol.12 No.1
소프트웨어 변경관리는 시스템의 변경된 내용을 프로그램이나 설명문서와 같은 특정 개체의 특성 변경에 초점을 둔 것이다. 변경관리 시 요구사항간의 상호종속적인 관계를 가지고 최적의 상태를 위하여 복잡한 의사결정을 필요로 한다. 본 논문은 소프트웨어 변경관리를 분산환경에서 컴포넌트들간에 시간과 상황에 따른 변화를 관리하는 모델을 설계 한다. 그리고 각 컴포넌트들간의 관계성들에 대한 정의를 하고 ANP 기법을 이용하여 분산환경에서의 각 컴포넌트가 변화되어 참조되는 상호 의존성을 고려하여 종속관계와 피드백을 이용하여 최적의 대안을 선택할 수 있다. 즉, 서로간의 관계된 의존도를 분석하여 3가지 형태의 변경관계를 나타내도록 하였다. 또한 의존도 분석을 통해 이러한 접근 방법의 유효성을 검증하였다. Software change management is focused on the change of a entity like the change of contents of a system or a document. In change management, interactive relationship among requirements and complex decision making is needed to obtain optimized status. In this paper we design a management model of software change management in distributed environment which mange the change among components by time and situation. In addition, each components are defined and use ANP technique for best decision-making by using the subordinate relationship and feedback considering the mutual dependency referring the change of components in distributed environment. Thus, we analyze the dependency among each components and show 3 types of change relationship. Also through analysis of dependency, we verified the effectiveness of such approach.