이 연구의 목적은 단조하중과 반복하중올 받는 철근콘크리트 면부재 해석에 대한 이방향성 회전 직교촉 모 텔의 성능올 검토하기 위함이다. 여기서 다루는 구조부재는 철근에 의하여 적절히 보강된 보， 기퉁， 보-기둥 접합부， 그리고 전단벽둥으로 부재의 파괴가 인장균열후 압축파괴에 의하여 일어나는 부재이다. 보통 단조하 중에 대하여 사용도는 이방향성 회전 직교축 모텔을 반복하중에 대하여 확장하며， 철근파 부착의 기존 재료모 델과 함께 유한요소해석에 사용한다. 단조하중에 대하여 이방향성 회전 직교축 모델올 사용한 해석 결과는 취 성파괴를 나타내는 철근콘크리트보의 실험결과와 비교된다. 또한 반복하중올 받는 전단벽의 극한하중， 비선 형 변형， 핀칭 현상동에 대하여 실험결과와비교된다.

자유 모양을 한 적층판 형태의 복합 회전체 쉘 구조물은 원추형 쉘 요소의 조합으로 나타낼 수 있다. 이에 이 논문에서는 원추형 쉘 요소에 대한 유한요소해석 모델을 개발하고자 한다. 또한 이 모델의 타당성을 입증하기 위해 기존의 원통형 쉘으 고유진동 이론해와 비교한다. 여러 형태의 복합 원통형 쉘에 대해 여러 가지 인자변환 실험을 행한다. 실험을 통하여서 이 논문에서 제시한 모델을 이용한 고유진동 주파수 결과와 이론해에서 구한 결과가 매우 흡사하다는 것을 알았으며 그로 말미암아 이 모델의 적합성을 확인하였다. 이 원추형 쉘 요소의 개발로 말미암아 어떠한 형태의 적층 이방성 복합 회전체 쉘에 대해서도 해석이 용이하다.

As the first step of study on fabrication of ceramic powders from phytoliths in rice, especially in rice husks, pulverization method of rice husks and the properties of milled rice husks were investigated. Impact methods, such as ball milling, were not meaningful for pulverizing elastic and thin fabric structure of rice husks. The most effective one was cutting method. In the present work, a rotating knife cutting method was applied to pulverizing rice husks. A 40-mesh screen was inserted under the rotating knives. The most portion of the milled powder was found in -50/+100 mesh section. Morphology of the milled rice husks revealed that the husks larger than 70 mesh were flake-like shape, at -70/+100 mesh section relatively equi-axed shape, at -170/+325 mesh section rod-like shape, and below 325 mesh section dust-like shape. Tap density of raw rice husks was about 0.1 , while those of milled rice husks were over . This meant that, for a given volume of reactor, raw material charge can be increased more that 4 times when using milled rice husks than unmilled one. True densities of unmilled and milled rice husks were higher than , and increased with decreasing milled sizes.

Atomizing mode and powder characteristics of CuA1Ni base shape memory alloy in rotating disk atomization were investigated in accordance with disk materials and additional elements. Produced powders were classified into two types of spherical and flake shape. In the case of CuAlNiBTi and CuAlNiZr alloy, high yield rate and fine powder were obtained. This tendency was same when we used oxide coated disks. We concluded that this results were steno from the wetting characteristics change between molten metal and disk surface. Especially, due to the reactive properties of Ti and Zr with ceramic disk, the change of atomizing appearance and powder characteristics were noticeable.

This study was conducted to develop a new RBC process available for the effective removal of organic matters and nitrogen in sewage. The RBC process for the oxidation organic compounds and nitrification was designed to occur at the 1st-stage and next-stage RBC respectively. Then nitrified water was recycled to the denitrifying RBC located at the lower part of the 1st-stage RBC. Some results were summarized as follows. 1. The loading limitation was represented as $60g{\cdot}COD/gm^2/day$ in experiment of simultaneous removal of organic matter and nitrogen. The maxmum COD % removal was 85% at the load $35g{\cdot}COD/m^2/day$. 2. The $NO_3-N$ % removal was approximately 80% at the load $60g{\cdot}COD/m^2/day$ and the maximum $NO_3-N$ remaval rate was $3.9g{\cdot}COD/m^2/day$ and the overall C/N ratio of 11.0 as required to achive 80% of $NO_3-N$% removal. 3.$NO_3-N$ removal rate was rapidly decreased above the load $7g{\cdot}NH_4{^+}-N/m^2/day$ and the maximum $NO_3-N$ removal rate was $3.7g{\cdot}NO_3-N/m^2/day$. 4. Irrespective of the recycle ratio, the COD % removal at the system of 2-stage RBC unit was nearly constant as 89% while the maximum one in the 1st-stage unit was 77% in the case of 50% recycle. 5. The maximum COD % removal in the 3-stage RBC system was 93% while 1st-stage one being 80%, under the $NH_4{^+}-N$ load of $7.4g/m^2{\cdot}d$. Also maximum percentage of nitrification and denitrification was 69% and 41% respectively, under the same $NH_4{^+}-N$ load.

고탄소 Dr-Ti 합금강의 회전접촉 피로마모실험에서 실험조건에 따라 다르게 변화하는 subsurface zone의 가공경와의 정도를 잔류응력의 분포로서 조사하였다. 시험전 표면잔류응력은 마모특성에 영향을 주지 못하였고, 접촉응력과 회전속도가 증가할수록 표면 잔류응력은 감소하여 갔으나 subsurface zone내의 최대압축잔류응력은 증가하였고, 그의 포화깊이는 깊었다. 이들 실험결과와 이론적 전단응력의 분포와의 관계에 관하여 검토하였다.

This paper describes an application of artificial neural network to diagnose the defects of rotating machiner. Induction motor was used to the object of defect diagnosis. For defect diagnosis, the frequency spectrum of vibration was utilized. Learning method of applied neural network was back propagation. Neural network has following advantage; Once it has been learned, inference time is very short and it can provide a reasonable conclusion regardless of insufficient input data. So, this defect diagnosis system can be used superiorly to rule based expert system as quality inspection of rotating machinery in the shop.

The environmental structure of T Tauri star can be understood by its continuum energy distribution. We suggest four evolutionary stages on the base of this environmental change from molecular cloud to the main sequence. A protostar is embedded in a dense envelope which can be attributed to the overall infrared region in continuum spectra. The infalling material from the envelope results in producing a hump in the mid-infrared region. This matter produces a surrounding disk around a central star afterwards. The disk emission changes the spectral index in the overall infrared region. The disk will be developed to a ring structure owing to the formation of planets by its instability and/or the cleaning effect of the inner region of the disk by a central star outflow, contributing to producing a hump in the far-infrared region. The pre-main sequence evolution points of T Tauri stars in H-R diagram strongly support the environmental structure evolution.

Even though it is well known that the tidal current in the East China Sea rotates clockwise, few report can be found about the precise pattern of it. To furnish some information available for the stow net fishermen, the author carried out the observation over 235 semidiurnal tidal cycle to investigate the pattern of the set and the rate of tidal current in the Korean fishing section 250 and 494, by reading the current meter and by tracing the corner reflectors with radar onboard the anchored obsen'ation vessel, from May 12, 1984 through February 27, 1986. The results obtained are as follows: 1. The mean semidiurnal tidal cycle was 12 h 20 m during spring tide, and 12 h 30 m during neap tide. 2. The mean interval from the calculated time of high water until the current began to set north was 2 h 30 m and 2 h 15 m in the fishing section 250 and 494 respectively, and the mean interval from the time of low water current began to set south was about 2 h 0 m in both sections. 3. In comparison of the occupied times to vary the set from one of 8 principal bearing points to the neighboring one, the shortest was while the set varied from N to NE and S to SW in the section 250 and 494 respectively. Contrary the longest was while the set varied from SE to S and from W to NW in the section 250 and 494 respectively. 4. In comparison of the rate while the set varied from one of 8 principal bearing points to the neighboring one, the fastest was while the set varied from SE to Sand NW to N in the section 250, and E to SE and W to NW in the section 494. Contrary the slowest was while the current set to NE and S W in the section 250, and N, NE and S W in the section 494.

本 硏究는 大氣大循環 過程에 나타나는 諸 現象들을 回轉流體의 實驗을 통해 나타내보임으로써 空間的인 난해한 槪念들을 학생들의 눈을 통해 직접 觀察하여 구체적으로 理解토록 했다. 回轉流體의 흐름을 可視化하고 溫度差와 回轉率에 따라 나타나는 여러 가지 유체의 운동을 觀察하며 大氣에서 나타나는 현상과 力學的으로 비교한다. Thermal Rossby number가 매우 크면(저회전 또는 큰 온도차) 熱帶에서 나타나는 Hadley 循環에 해당하는 원형의 흐름이 나타나고 이 값이 차츰 감소함에 따라(회전수 증가) 中緯度의 편서풍대에 나타나는 偏西風 波動이나 zet 氣流 등의 定常波에 해당하는 Rossby 循環의 흐름을 볼 수 있다. Thermal Rossby number가 더욱 감소하면 폐색된 低氣壓이나 高氣壓 등이 나타나며 低指數 循環에 해당하는 不規則한 흐름을 볼 수 있다. 이 실험을 통해 이러한 現象들이 또한 熱을 赤道로부터 高緯度로 운반하는 重要한 역할을 하게 됨을 알고 反射鏡과 回轉鏡 裝置를 開發함으로써 유체 흐름의 種類와 現象들을 靜止系에서 뚜렷하게 觀察할 수 있게 되어 敎育器材로서의 效能이 크다고 본다.

This paper proposes a simple and intuitive model-free torque-tracking control for rotary electro-hydraulic actuators. The undesirable natural-velocity-feedback effect is discussed by introducing mechanical impedance into the electro-hydraulic actuation system. The proposed model-free torque control comprises inner- and outer-loop control to achieve two control objectives. Inner-loop control reduces the mechanical impedance passively and optimally. To improve the tracking accuracy, a certain form of proportional-integral-derivative control is applied to the outer loop. The robustness of the proposed closed-loop system against external disturbances is demonstrated by transforming the two-loop control structure into a disturbance observer form. The proposed method is validated on a single joint electro-hydraulic actuator.

This paper presents the kinematic modeling of the human forearm rotation constructed with a spatial four-bar linkage. Especially, a circumduction of the distal ulna is modeled for a minimal displacement of the position of the hand during the forearm rotation from the supination to the pronation. To establish its model, four joint types of the four-bar linkage are, firstly, assigned with the reasonable grounds, and then the spatial linkage having the URUU (Universal-Revolute-Universal-Universal) joint type is proposed. Kinematic analysis is conducted to show the behavior of the distal radio-ulna as well as to evaluate the angular displacements of all the joints. From the simulation result, it is, finally, revealed that the URUU spatial linkage can be substituted for the URUR (Universal-Revolute-Universal-Revolute) spatial linkage by a kinematic constraint.