• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.180-185
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• 2001

In order to regulate the physical characteristics of an ocean dumping material in the south-eastern East Sea, the diffusion characteristics with the observation, hydraulic experiment and numerical experiment data are investigated. The main results are as follows; (1) Spying CTD observation result of the area of Jung in the East Sea, the ocean dumping area had influenced the Tsushima warm current of high temperature and salinity. Horizontal turbulent diffusivity is 1.913${\times}$10$^{7}$ $\textrm{cm}^2$/sec by drogue tracking. (2) From the experiment of settling, the initial settling velocity of each material is 1.0∼2.7 cm/sec according to the specific gravity and initial concentration. In the pycnocline, particles didn't settle under the pycnocline any more and accumulated. It is signified that calculation of the sedimentation rate of the ocean dumping material including of vertical diffustion must be regard the pycnocline in the ocean area have well-developed pycnocline. (3) Vertical turbulent diffusivity were 2.219${\times}$10$^{-8}$∼8,874${\times}$10$^{-4}$ $\textrm{cm}^2$/sec from the experiment of settling. And, the pycnocline influenced the vertical turbulent diffusivity. (4) From the result of diffusion simulation in the East Sea, the co-concentration line of 0.05 ppm and 0.1 ppm are limited at dumping area after 200 days. The constant concentration line of 0.01 ppm is distributed to the vicinity of Ulleungdo and Tokdo, but isn't distributed to the coastal area of East Sea and southern area of Jung in the East Sea.

• The Korean Journal of Zoology
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• v.37 no.1
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• pp.49-57
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• 1994

In the course of an investigation on the morphological variation of Korean striped bittering, Acheilognathus vamatsutae Mori, two kinds of morrholoflical types were found. Some morphological characters were compared between them and multivariate analysis was conducted. Since the difference of the barbel length between them was very significant (p < 0.01,1-test), they should be designated as L-and 5-type Hshes: fishes with long barbels and those with should barbels, respectively. Lateral line scales, snout length and prepectoral length showed a tendency that the observation could be distinguished from each other (p < 0.05, Duncan's multiple range tests. There were no individuals over 70 mm BL in S-type and so S-type fishes were somewhat dwarf than L-type fishes. The two types were also clearly distinguished by multivariate analyses using cluster and discriminant analyses. According to the observation on the four populations of the Naktong River, the blue-green stripe on the body side and the white band on the margin of anal fin in males of S-type fishes were well developed through the year but those of males of L-type fishes completely disappeared or became slender during nonbreedins season as that of females. Of the seven localities surveved, there were no places that the two types cohabit. S-type fishes are limited only in the Kumho and Wichon River of the Naktong River system but L-type fishes are distributed more widely In the Hongchon, Mangvons, Somjin, Mirang and Panbyon River.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.289-299
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• 2019

Attitude control modeling and simulation (M&S) can be extensively applied in overall development process, from simple algorithm design to on-board software verification. This paper introduces CMG-based attitude control M&S software, which consists of 6-DOF modeling (CMG and space environments modeling), and attitude control algorithm. The M&S software is divided into three modules, from an inner CMG motor control module to an outer earth observation mission module. While an application of this developed software is currently limited to the initial-phase attitude controller development, its application area can be extended to the later-phases by considering sophisticated model information in future.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.49-56
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• 2022

S-STEP is a small SAR satellite mission that monitors time-limited emergency targets and military anomalies in areas of interest, achieving the average revisit in less than 30 minutes by deploying a constellation of 32 satellites in low orbit at an altitude of 510 km. The mission operation mode of S-STEP is divided into normal mode, observation mode, communication mode, and orbit maintenance mode. Further,, the attitude control mode is subdivides into initial detumbling, sun pointing, target pointing, ground station pointing, and thrust direction maintenance. Based on the preliminary mission operational scenario and the satellite's characteristics, this study analyzed the attitude control performance during initial detumbling and observation modes. It verifies that each mode's attitude control accuracy requirements within the time allotted by the scenario of the S-STEP achieved.

• Smart Structures and Systems
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• v.31 no.2
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• pp.131-140
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• 2023

As well-known, the extended Kalman filter (EKF) is a powerful tool for parameter identification with limited measurements. However, traditional EKF is not applicable when the external excitation is unknown. By using least-squares estimation (LSE) for force identification, an EKF with unknown input (EKF-UI) approach was recently proposed by the authors. In this approach, to ensure the influence matrix be of full column rank, the sensors have to be deployed at all the degrees-of-freedom (DOFs) corresponding to the unknown excitation, saying collocated measurements are required. However, it is not easy to guarantee that the sensors can be installed at all these locations. To circumvent this limitation, based on the idea of first-order-holder discretization (FOHD), an improved EKF with unknown input (IEKF-UI) approach is proposed in this study for the simultaneous identification of structural parameters and unknown excitation. By using projection matrix, an improved observation equation is obtained. Few displacement measurements are fused into the observation equation to avoid the so-called low-frequency drift. To avoid the ill-conditioning problem for force identification without collocated measurements, the idea of FOHD is employed. The recursive solution of the structural states and unknown loads is then analytically derived. The effectiveness of the proposed approach is validated via several numerical examples. Results show that the proposed approach is capable of satisfactorily identifying the parameters of linear and nonlinear structures and the unknown excitation applied to them.

• Journal of Chest Surgery
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• v.47 no.2
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• pp.106-110
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• 2014

Background: There are several modalities of coronary artery revascularization for multivessel coronary artery disease. Hybrid coronary revascularization (HCR) with minimally invasive direct coronary artery bypass grafting was introduced for high-risk patients, and recently, many centers have been using it. Limited incisional full sternotomy coronary artery bypass (LIFCAB) involves left internal thoracic artery (LITA)-to-left anterior descending coronary artery (LAD) anastomosis through a sternotomy with a minimal skin incision; it could be considered another technique for minimally invasive LITA-to-LAD anastomosis. Our center has performed HCR using LIFCAB, and in this paper, we report our short-term results, obtained in the past 3 years. Methods: The medical records of 38 patients from May 2010 to June 2013 were analyzed retrospectively. The observation period after HCR was 1 to 37 months (average, $18.3{\pm}10.3$ months). The patency of revascularization was confirmed with postoperative coronary angio-computerized tomography or coronary angiography. Results: There were 3 superficial wound complications, but no mortalities. All the LITA-to-LAD anastomoses were patent in the immediate postoperative and follow-up studies, but stenosis was detected in 3 cases of percutaneous coronary intervention. Conclusion: HCR using LIFCAB is safe and yields satisfactory results from the viewpoint of revascularization for multivessel disease.

• The Korean Journal of Community Living Science
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• v.28 no.3
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• pp.415-428
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• 2017

The purpose of this research was to develop healing food dishes for the vitalization of forest healing tourism in agricultural areas by enhancing satisfaction of food experiences by visitors to Mount Chungnyeong, Jangseong. Results from site visitation by three professors from food-related departments, association opinions, Jangseong-gun policies, and research materials relating to healing foods were applied for the preparatory experimental cooking, and the final dishes were selected through a food demonstration event. As a result of observation during the site visitation, the main dishes of the subject restaurant appeared to be limited to Samchae Bibimbap, Samchae Ddeokgabi, and Korean set menu items, revealing a limited selection for tourists and referencing a failure to induce customer attraction and long-term stay. Development of a menu conforming to the image of forest healing at Mount Chungnyeong is desperately needed. As a result of applying the results of the surveys from visitors to Mount Chungnyeong, the types of dishes preferred appeared to be Korean table d'hote and Bibimbap, and pork was preferred as the $entr{\acute{e}}e$. The characteristics of preferred dishes appeared to be based on tradition and regionality. Thus, Forest Healing Savory Dish, Yellow Health Dish, and Samchae Kalguksu applying the policy direction of the Yellow City, Jangseong-gun and the image of Jangseong-gun based on Confucianism were developed. Tourists may further enhance the effectiveness of forest healing through foods based on dishes by adding traditional taste using seasonal food ingredients and local specialties, which can contribute to the vitalization of forest healing tourism.

• Journal of Chest Surgery
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• v.26 no.9
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• pp.667-676
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• 1993

Boprosthetic cardiac valves fail from biological and metabolic as well as mechanical reasons, and the limited durability is the main factor of marked withdrawal in their clinical use. Starting the use of bioprosthetic valves in 1976, up to the end of 1992, the consecutive 178 patients have undergone re-replacement of glutaraldehyde-treated xenograft valves for primary tissue failure [PTF]among the patients who had initial valve replacement at Seoul national University Hospital. The explanted valves were 69 porcine aortic [51 Hancock, 12 Angell-Shiley and 6 Carentier-Edwards] and 141 bovine pericardial [129 standard-profile and 12 low-profile ionescu-Shiley] valwes, with an overall incidence of PTF of 15.2%. The operative mortality rate of re-replacement was 5.1%. Calcific degeneration and tissue damage in relation to calcification were the most frequent modes of PTF on gross examinatin of the explanted valves resulting hemodynamically in valvular regurgitation. The number of Hancocg porcine and the standard-profile Ionescu-Shiley valves in valves in mitral position failed more often from tissue damage [tears, holes, and loss or destruction of cuspal tissue] than calcification [68.3% vs. 39.0%, p<0.01] with resultant regurgitation in 61%, the Ionescu-Shiley valves in the same position in 53%. The tendency of more calcification than tissue damage[71.3% vs. 33.3%, p<0.001]with stenosis in 53%. The tendency of more calcification and immobility of cusps in the latter group was partly explainable by the inclusion of patients of pediatric age. Observation made in this study suggest : many of bioprosthetic valves would fail from calcification and tissue damage : some fail prematurely because of mechanical stress probably owing to the valve design in construction ; andeven those valves escaped early damage would be subject to calcify in the prolonged follow-up period. In conclusion, at the present time, the clinical use of bioprostheticxenograft valves seems to be quite limited until further improvement in biocompatibility and refinement in valve design in manufacture are achieved.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.923-928
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• 2014

Communication underwater is severely limited when compared to communications in air because water is essentially opaque to electromagnetic radiation except in visible range. Acoustic systems are capable of long range communication, but offer limited data rates and significant latency due to the speed of sound in water. On the other hand, optical wireless communication has been proposed as one of the best alternatives to meet the requirements of the underwater observation and subsea monitoring systems. It will help In this study, we are developing an underwater optical communication system that integrates with a depot ship floating on the water. An interface between LED lighting communication system and Bluetooth module is presented to support the underwater-to-air communications. Error free image and text transmission at 3 m of water were achieved at bit rates of 230.4 kbps. This development effort will enhance infrastructure to efficiently interconnect between underwater wireless systems and command ship networks for underwater monitoring.

• Korean Journal of Cognitive Science
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• v.24 no.2
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• pp.95-109
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• 2013

With the rapid evolution of the personal device environment, the demand for natural language applications is increasing. This paper proposes a morpheme segmentation and part-of-speech tagging model, which provides the first step module of natural language processing for many languages; the model is designed for mobile devices with limited hardware resources. To reduce the number of morpheme candidates in morphological analysis, the proposed model uses a method that adds highly possible morpheme candidates to the original outputs of a conventional left-longest-match-preference method. To reduce the computational cost and memory usage, the proposed model uses a method that simplifies the process of calculating the observation probability of a word consisting of one or more morphemes in a conventional hidden Markov model.