This paper describes the design of H-infinity controller for robust control of a DC motor system. The suggested controller can ensure robustness against disturbance and model uncertainty by minimizing H-infinity norm of the transfer function from exogenous input to performance output and applying the small gain theorem. In particular, the controller was designed to reduce the effects of disturbance and model uncertainty simultaneously by formalizing these problems as a mixed sensitivity problem. The validity of the proposed controller was demonstrated by computer simulations and real experiments. Moreover, the effectiveness of the proposed controller was confirmed by comparing its performance with PI controller, which was tested under the same experimental condition as the H-infinity controller.

A 20-year-old woman who had a main symptom of intermittent pain in both mandibular third molar visited our hospital. In CBCT findings, the #38, 48 teeth were located on the lingual side of the inferior alveolar nerve. In addition, a large stone about 12mm in length was observed in the right Wharton's duct in CBCT findings. Neck CT scan was performed and a large stone about 12mm in length was observed, and the accumulation of saliva in the rear of the stone was observed. The patient underwent sialolithotomy and #38, 48 tooth extraction through intraoral approach under general anesthesia. The removed stone was similar in shape and color to a tooth. The removed stone was markedly fragmented and composed of dentin and enamel-like tissue which showed lamellate arrangement in microscopic examination. Patient was presently symptom free after 10-months postoperatively.

This paper deals with the disturbance observer (DOB) based sliding mode control (SMC) for a DC motor to control motor rotating speed precisely and to ensure strong robustness against disturbance including load torque and parameter variation. The reason of steady state error in speed on conventional SMC without DOB is analyzed in detail. Especially, the suggested DOB is designed to prevent measuring noise and harmonics caused by derivative operation on rotating speed. The control performance of the DOB based SMC is evaluated by the various simulations. The simulation results showed that the DOB based SMC had more robust performance than the SMC system without DOB. Especially, precise speed control was possible even though motor parameter variation and load torque was added to the system.

Thousands of demersal fishes inhabit in the waters around Korea and most of them are overexploited. One of reasons is technological development, which increases the efficiency of the vessels continuously. The analysis was conducted to identify the change of fishing power index to develop the vessel and gear technology that may have improved the fishing efficiency of the Danish seine fishery from 1960s to 2010s. Gross tonnage was decreased stably, but the horse power was increased annually. The length of ground rope, warp and hand rope was somewhat longer, but changed a little. Color fish finder was utilized from the mid-1960s and positioning system was used five years later. A hydraulic line hauler were introduced in the mid-1980s, and supply rate was gradually increased. Surveys on the supply and upgrading of fishing equipment utilized visiting researchers. Therefore, the relative fishing power index in the Danish seine fishery increased stably from 1.0 in 1970 to 1.0 in 1980, to 1.2 in 1990, to 1.3 in 2000 and to 1.3 in 2010. The results are expected to contribute to reasonable fisheries stock management.

The small yellow croaker (Larimichthys polyactis) is one of the representative high-class fish species in Korea. The catch of small yellow croaker in adjacent water fisheries has been continuously decreasing from 59,226 tons in 2011 to 19,271 tons in 2016. The small yellow croaker is caught by gillnet, stow net and bottom trawl, among which about 55~65% is caught by gillnet. For the sustainable use of small yellow croaker, the fishing power of small yellow croaker drift gillnet is very important. Therefore, the change of fishing power index were analyzed to identify the development of the vessel and gear technology that may have improved the fishing efficiency of the small yellow croaker drift gillnet fishery from 1960s to 2010s. Gross tonnage and horse power per fishing vessel was increased annually. The mesh size was 75.0 mm in the 1960s, but reduced to 60.6 mm in the 1980s and to 51.0 mm in the 2000s. In the 1960s, it was hauled out by manpower. However, the net hauler were modernized and supply rate was also increased since 1970. Due to the mechanization of the net hauler, the number (length) of used net gradually increased from 1.5 km in the 1960s to 7.5 km in the mid-1980s and to 15 km in 2010. Colour fish finders and positioning system were introduced and utilized from the mid-1980s. Surveys on the supply and upgrading of fishing equipment utilized visiting research. Therefore, the relative fishing power index in the small yellow croaker drift gillnet fishery increased from 1.0 in 1980 to 0.8 in 1970, to 1.1 in 1990, to 1.6 in 2000 and to 1.9 in 2010. The results are expected to contribute to reasonable fisheries stock management of the small yellow croaker drift gillnet fishery.

본 연구는 기업 관리자의 코칭리더십과 조직구성원의 문제해결능력 및 대인관계능력간의 구조모형의 타당성과 코칭리더십과 문제해결능력이 대인관계능력에 미치는 경로에 따른 영향력을 규명하고자 하는 목적을 가지고 연구를 수행하였다. 이러한 연구목적을 달성하기 위하여 국내 주요 대기업에서 근무하는 사무/관리직 492명을 대상으로 실증연구를 실시하였다. 이러한 분석을 위한 통계처리에는 SPSS와 AMOS 통계프로그램이 사용되었다. 연구결과 코칭리더십은 문제해결능력에 직접적인 영향을 미치고 문제해결능력을 매개로 대인관계능 력에 간접적인 영향을 미친다는 구조모형은 타당한 것으로 밝혀졌다. 그리고 기업 관리자의 코칭리더십 과 조직구성원의 문제해결능력이 다양한 구조적 경로를 통하여 조직구성원의 대인관계능력 향상에 긍정 적인 기여를 하는 것으로 밝혀졌다. 즉, 직무기반 코칭리더십과 관계기반 코칭리더십 모두가 문제해결능 력 향상에 긍정적인 기여를 하고, 이중 관계기반 코칭리더십이 직무기반 코칭리더십보다 문제해결능력 에 더 큰 영향을 미치고, 코칭리더십이 조직구성원의 문제해결능력을 매개로 대인관계능력 향상에 긍정 적인 기여를 하는 것으로 확인되었다.

The contemporary high-tech structures have become enlarged and their functions more diversified. Steel concrete structure and composite material structures are not exceptions. Therefore, there have been on-going studies on fiber reinforcement materials to improve the characteristics of brittleness, bending and tension stress and others, the short-comings of existing concrete. In this study, the purpose is to develop the estimated model with dynamic characteristics following the steel fiber mixture rate and formation ration by using the nerve network in mixed steel fiber reinforced concrete (SFRC). This study took a look at the tendency of studies by collecting and analyzing the data of the advanced studies on SFRC, and facilitated it on the learning data required in the model development. In addition, by applying the diverse nerve network model and various algorithms to develop the optimal nerve network model appropriate to the dynamic characteristics. The accuracy of the developed nerve network model was compared with the experiment data value of other researchers not utilized as the learning data, the experiment data value undertaken in this study, and comparison made with the formulas proposed by the researchers. And, by analyzing the influence of learning data of nerve network model on the estimation result, the sensitivity of the forecasting system on the learning data of the nerve network is analyzed.

The dentigerous cyst is defined as a cyst that originates by the separation of the follicle from around the crown of an unerupted tooth. This is the most common type of developmental odontogenic cyst, making up about 20% of all epithelium-lined cysts of the jaws. Large dentigerous cysts are uncommon, but some cases are large cysts. The usual treatment for a dentigerous cyst is careful enucleation of the cyst together with removal of the unerupted tooth. Large dentigerous cysts also may be treated by decompression. This permits decompression of the cyst, with a resulting reduction in the size of the bone defect. The cyst can then be enucleated at a later date with a less extensive surgical procedure and important structures such as teeth and the inferior alveolar nerve can be preserved. These cases are large dentigerous cysts treated by decompression. Less extensive surgical procedures were used and some teeth were preserved.

Fibrolipoma, a variant of lipoma, is rare in oral cavity, and the pathogenesis is uncertain. The diagnosis and differentiation of fibrolipoma with other clinically similar lesions is very essential for proper treatment planning. We present a case of fibrolipoma on palate of a 28-year-old male.

We report a rare case of intraosseous epidermoid cyst in mandibular body. A non symptomatic patient without trauma history had a cystic lesion on mandible close to the third molar. The lesion was enucleated while extracting of left lower third molar. The microscopic findings were consistent with an epidermoid cyst. Key words：Epidermoid Cyst, Intraosseous, Mandible

Sialolith is a common disease of salivary glands characterized by the development of salivary stones, resulting in the salivary ductal obstruction. The chief complaints of patients with sialoliths are pain and swelling of the involved gland during meals. Most sialoliths are found in the submandibular gland of middle-aged patients. The size of the salivary stones can vary, but most of them are less than 10mm in size, giant sialoliths(larger than 15mm) are very rare. In this case, we report a 68-years old female patient who had removal of a giant sialolith located in left proximal Wharton’s duct by less invasive intraoral surgical technique successfully. We also review related literature.