임의의 체눈 모양에서 어떤 절점에서 출발하여 출발한 절점으로 되돌아 오는 최단 경로를 탐색함으로써 2차원 유한요소의 연결관계를 자동추출할 수 있는 방법을 개발하였다. 한 절점에서 가능한 여러 경로 중에서 가능성이 큰 경로만을 탐색하게 하였고 추출된 경로에 대하여 요소로서의 유일성 및 적합성을 검사하였다. 제안된 방법이 완전함을 증명하였으며 예제를 통하여 일반적인 자동발생 기능의 적용이 어려운 체눈 모양에 대해서도 정확하게 요소를 추출할 수 있음을 보였다.

Avoiding the industrial accidents is one of the goals in manufacturing industries from the top manager to the foremen. Therefore all the companies try to prevent occupational accidents using system safety programs in order to increase the productivity. Korean industries have been tended to depend upon historical information to control risks. The other hand, foreign industries have identified risk factors using system safety techniques to predict future risks. This study presents the method to apply the foreign industries risk control technique to the Korean industries.

본 논문에서는 BLDC 서보모터의 속도 제어성 향상을 위해 속도제어계에 2자유도 적분형 최적 제어법을 적용하고 그 결과를 기존의 PI제어계 및 2자유도 PI제어계와 비교하였다. 2자유도 적분형 최적제어법은 PI제어법이 갖는 지령치 추종특성과 외란 억제특성간의 트레이드오프 문제를 해결하고, 제어계의 최적성을 확보하고자 도입되어졌으며, 시뮬레이션과 실험을 통해 그 유효성을 고찰하였다. 시뮬레이션을 통해 얻은 결과는 다음과 같다. (1) 2자유도 적분형 최적제어계는 PI제어계에 비해 양호한 지령치 추종성과 외란 및 모델링 오차제거 특성을 보였다. (2) 2자유도 적분형 최적제어계는 제어파라미터인 하중행렬 Q, R 및 W에 대한 제약요건이 없을 경우, 모터의 정격조건 하에서 이들을 적절히 설정함으로써 2자유도 PI제어계보다도 양호한 지령치 추종성과 외란 및 모델링 오차 제거 특성을 얻을 수 있다. (3) 2자유도 적분형 최적제어계는 인가전압 및 전류의 크기를 2자유도 PI제어계의 그것과 동일하게 제약할 경우 2자유도 PI제어계에 비해 지령치 추종에 관한 정정시간 외에는 그다지 우수한 성능을 보이지 않았다. 또한, 실험을 통해 고찰한 PI 및 2자유도 PI제어계의 속도추종성능은 시뮬레이션 결과와 거의 동일하였다. 2자유도 적분형 최적제어계에 대한 실험결과는 논문에 나타내지 못하였으나, PI및 2자유도 PI제어계의 실험결과에서 알 수 있듯이 2자유도 적분형 최적제어계도 시뮬레이션 결과와 같은 경향을 보일 것으로 사료된다. 따라서, 본 논문에서 검토된 방법은 기존의 PI 제어계가 갖는 지령치 추종과 외란억제의 트레이드오프 문제를 상당부분 해결 가능할 것으로 보인다. 또한, 일정의 부하외란 및 모델링 오차내에서는 2자유도 PI제어계 보다 나은 제어성능을 보여 BLDC 모터의 속도 제어성 향상에 기여할 수 있을 것으로 기대가 된다. 향후, 2자유도 적분형 최적제어계의 실험결과를 통한 엄밀한 제어성능검증과 스텝외란 외의 주기성 외란 인가시 2자유도 적분형 최적제어계의 외란제거 방안 등이 검토되어야 할 것으로 사료된다.

다공성 알루미나 소결체내부로 3Y-TZP 및 12Ce-TZP 전구체를 각각 액상침투시킴으로써 2종류의 Al2O3/TZP복합체를 제조하였다. 소량의 (~11.0 wt%) TZP의 첨가는 Al2O3소결체 (1600˚C, 2시간)의 강도 (19~59%)와 파괴인성(14~157%)을 증가시켰다. 3Y-TZP의 첨가는 복합체의 강도의 향상에 12Ce-TZP의 첨가는 인성의 향상에 보다 효과적이었다. 침투도니 TZP는 복합체의 내부보다 표면에 집중되었으며, 그 결과 이곳에서의 입성장에 빨랐고 Al2O3의입성장 억제효과도 상대적으로 뛰어났다. 입계 및 입내균열전파가 일어났으나 Al2O3/12Ce-TZP의 경우가 Al2O3/3Y-TZP에 비하여 입계파괴가 우세하였다

Inchon Port is the second largest import-export port of Korea, and has the point at issue such as the excessive logistics cost because of the limits of handling capacity and the chronic demurrage. There are few research activities on the analysis and improvement of the whole port operation, because Inchon Port not only has the dual dock system and various facilities but also handles a various kind of cargo. The purpose of this paper is to develop the simulation program as a long-term strategic support tool, considering the dual dock system and the TU(Terminal Operation Company) system executed since March, 1997 in Inchon Port. The basic input parameters such as arrival intervals, cargo tons, service rates are analyzed and the probability density functions for these parameters are estimated. The main mechanism of simulation model is the discrete event-driven simulation and the next-event time advancing. The program is executed based on the knowledge base and database. From the simulation model, it is possible to estimate the demurrage status through analyzing various scenarios and to establish the long-term port strategic plan.

The purpose of this study was to develop a breeding technique to increase Hanwoo of superior characteristics. In the present study, reproductive status of Hanwoo such as size of farm, breeding system and gestationi length was investigated. In addition, effect of low dose administration of prostaglandin F2(PGF2) on luteolysis was examined. The size of farm was classified by the total number of cows and the number of breeding stocks, respectively. The distribution of herd size of < 5, 6~10, 11~30, 31~50 and > heads was 31%, 15%, 39%, 4% and 11%, respectively. Furthermore, the distribution of breeding stock size of <5, 6~10, 11~30, 31~50 and > 50 heads was 36%, 28%, 31%, 3% and 3%, respectively. Average parity was 2.1 in breeding stock. In breeding pattern, artificial in semination(A.I), estrus synchronization-A.I and natural mating was 92.7%, 2.4% and 4.9% respectively. Gestational length of Hanwoo was ranged 253~316 days (average length : 285 days) after estrus( estrus=0). To induce luteolysis, PGF2 was injected into ovarian parenchyma by a modified ovarian injector. The effect of administration of 6mg PGF2 on luteolysis and estrus induction was betweer (P<0.01) when PGF2 was administered into ovarian parechyma than when administered intramuscluarly (71 vs. 91%). When PGF2 was injected into ovarian parenchyma, a decreased concentration to 3 mg did not significantly decreaed its luteolytic effect(92%). When AI was performed following PGF2 treatment, the intraovarian injection group yielded a higher pregnancy rate(69 vs. 88%) than the IM injection groups, regardless of the dosage. In conclusion these results suggest that increasing herd size and regular reproductive management are needed to improve reproductive efficiency in Hanwoo industry. Furthermore, intraovarian administration of PGF2 is effective way to induce luteolysis compared with intramuscular injection.

Despite research to treat delayed onset muscle soreness (DOMS), no effective treatment has been reported. The purpose of this study is to investigate the effect of a hold-relax technique and cryotherapy on DOMS. Thirty-three subjects were randomly assigned to one of three treatment groups: control, hold-relax technique, or hold-relax technique and cryotherapy. DOMS was induced in the non-dominant biceps muscle through repeated eccentric contractions. Resting elbow joint position, flexion and extension (universal goniometer), pain (Visual Analogue Scale; VAS), and WBC count (blood analysis) were measured one hour before DOMS was induced and 24, 48, and 72 hours after DOMS was induced. The data were analyzed by repeated measure of two-way ANOVA. The results of this study were summarized as follows: 1) While analysis showed no significant differences between groups in relation to a resting elbow joint position, there were significant differences over time, especially at 24, 48 hours after DOMS was induced compared with resting elbow joint position before DOMS was induced. 2) While analysis showed no significant differences between groups in relation to range of flexion, there were significant differences between range of flexion before DOMS was induced and range of flexion 72 hours after DOMS was induced. 3) There were no significant differences between groups or over time in relation to range of extension. 4) While analysis showed no significant differences between groups in relation to VAS, there were significant differences over time in different hours. 5) There were no significant differences between groups or over time in relation to WBC count. 6) There were no interactions between groups or over time in all variables. This results suggested that hold-relax technique and cryotherapy were not effective to reduce DOMS.

A three-dimensional digital image processing technique is proposed to quantitatively predict the dispersion phenomena of oil droplet onto the surface of the water. This technique is able to get the dispersion rate of an oil droplet three-dimensionally just below the surface of the water over time. The obtained dispersion rate obtained through this technique is informative to the investigation into the relationship among the gravity, surface tensions between oil, water, and air. This technique is based upon the three-dimensional PIV(Particle Imaging Velocimetry) technique and its system mainly consists of a three CCD(Charge Coupled Device) cameras, an image grabber, and a host computer in which an image processing algorithm is adopted for the acquisition of dispersion rate oil an oil droplet.

본 연구에서는 (N-docosyl quinolinium)-TCNQ (1:2) 착물의 LB초박막을 제작하였다. LB막의 누적을 위한 최적조건을 구하기 위하여 subphase 온도, barrier 압축속도 및 분산량을 변화시키면서 표면압-면적(π-A) 등온선 특성을 측정하였다. 그리고 전이비, UV-vis의 최대 흡광도, 정전용량 및 두께를 측정하여 LB막의 누적상태를 확인하였다. 그 결과 분자수준으로 잘 제어된 양호한 LB막이 제작되었음을 알 수 있었다..

Free from the industrial accident is the goal from top manager to foreman. Therefore all the company try to prevent occupational accident using system safety program in order to increase productivity Korean industries have been tend to depending upon historical information to control risk. The other hand, foreign industries have been Identify risk factors using system safety techniques to predict future risk. Therefore, this study is presented to applying the foreign industries's risk control technique to korean industries.

Too many big accidents have been occurring in Korea during '90. Those were accidents of Sung-Soo Bridge in 1994 and Sam-Poong Department Store in 1995. It was confirmed that the causes of the accident were unreliable construction or building. Therefore, in this study are to use technique of virtual reality(VR) simulation in order to prevent construction accidents. To set up the VR in safety construction, Date Base of variables, VR model and expert system are needed. This system is to build expert system, to visualize of the VR system and navigation, and to find out design errors of construction. Therefore, the purpose of this was to analyze accident type of construction, and apply VR system for simulation technique.

본 논문의 목적은 막구조물의 형상해석, 응력-변형 해석, 재단도 해석을 수행하는 것이고, 재료는 선형탄성, 응력은 평면응력의 상태로 가정한다. 케이블 및 막구조물은 외력에 대한 변형이 매우 큰 구조물이기 때문에 기하비선형을 고려한 비선형해석을 하여야 한다 해석은 일반적인 구조물과는 달리 다음의 3단계로 구성된다. 첫 번째 단계는 초기 평형형상을 결정하기 위한 형상해석이고, 두 번째 단계는 다양한 외력이 가해졌을 때 구조물의 거동을 파악하는 응력-변형 해석이다. 이렇게 하여 일단 만족된 형상이 얻어지면 형상해석에서 얻은 결과를 기초로 하여 시공적 관점의 재단도 해석이 수행된다. 본 논문에서는 서귀포 월드컵 축구 경기장 지붕 구조물의 예를 들어 형상해석, 응력-변형 해석, 재단도 해석을 수행하고, 카테노이드(Catenoid) 구조물을 이용하여 최적재단도에 관한 해석기법을 제시한다.

본 논문에서는 다지지점 가진에 의한 구조물의 동적응답을 구하기 위하여 유한요소모형을 수정하고 등가하중을 도입하는 간단한 기법을 제안하였다. 제안방법은 다지지점 입력에 대한 해석기능이 있는 기존의 범용구조해석 S/W를 이용한 선형 및 비선형 해석결과와 비교하여 검증하였다. 이 기법은 다지지점 입력에 대한 해석기능이 없는 범용유한요소해석 S/W 및 비선형 구조해석을 위하여 특별히 개발되었던 전산프로그램을 이용하여 다지지점 입력에 대한 지진응답해석을 수행할 때 유용하게 활용될 수 있을 것으로 기대된다.