• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.6 no.2
• /
• pp.59-66
• /
• 2007

Voice coil actuator is used linear motion system that requires precision positioning control. In order to control precision positioning of voice coil actuator, relation model between duty ratio and moving displacement of voice coil actuator is needed. This paper present a duty ratio - displacement model in PWM control of voice coil actuator. Transfer function of voice coil actuator is obtained by combining voice coil motor's equation of motion with the equation of circuit and characteristic of voice coil motor. Consider to initial condition of velocity and current, transfer function is transformed mathematical model. The induced model can predict output displacement, velocity and current according to duty ratio and amplitude. The model is verified by experimental tests such as velocity and displacement response of voice coil motor. Simulated results have tracking errors of less than 10 percent of experimental results.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.12
• /
• pp.1269-1273
• /
• 2010

Typically users prefer to manage and access personal photo collections taken from a cell phone based on events. In this paper we propose an event clustering algorithm that requires low computation cost with high accuracy supporting incremental operation. The proposed method is based on the statistical analysis of the elapsed interval of intra-event photos on the real sample data for the decision of an event boundary. We then incorporate both location and visual information for the ambiguous range to split with only temporal cue. According to test results, we show higher performance compared to existing general clustering approaches.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.16 no.2
• /
• pp.5-24
• /
• 2005

This study reviews various kinds of records filing systems, which function as a basic fundamental to effective records management. The purposes, methods and characteristics of Alphabetic, geographic, numeric, subject, and combined filing systems are examined. The alphabetic filing method uses letters of the alphabet to determine the order of names of people and companies. In subject filing the subjects are filed in alphabetic order. In numeric filing, numbers representing names or subjects are used. When records are requested by place or location rather than by individual or business name, geographic filing is advantageous.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2010.07a
• /
• pp.53-56
• /
• 2010

본 논문은 Shannon의 정리에 따른 채널 용량에 근접한 성능을 보이는 것으로 알려진 터보 복호기 기반의 반복적인 검출과 복호화(Iterative Detection and Decoding) 기법에서 반복적인 복호화를 수행할 시에 제외되었던 리스트 구 복호기(List Sphere Decoder)에서 사전 정보(prior information)을 이용할 수 있도록 하여 수정된 IDD 기법을 제안하였다. 기존의 기법에서는 사후확률(A posteriori probability)을 계산하기 위하여 리스트 구 복호기를 사용하였으나 반복적인 복호화 수행 시에는 사전 정보를 이용하지 않는 특성으로 인하여 제외된다. 만약 잡음(noise) 등의 이유로 검출된 심볼 벡터 목록이 원래의 것과 매우 다른 경우라도 재 검출을 하지 않기 때문에 반복적인 복호화를 수행하더라도 원래의 정보에 근접하기 어렵게 된다. 본 논문에서는 이러한 기존의 기법에서 리스트 구 복호기를 터보 복호기의 Log Likelihood Ratio (LLR) 값을 사전 정보로 이용할 수 있도록 수정된 리스트 구 복호기를 제안하였다. 수정된 리스트 복호기는 반복적인 복호화를 수행 시 이전의 복호화에서 얻은 정보를 이용하여 새로이 검출된 심볼 벡터 목록을 제공하게 된다. 실제의 통신환경과 유사한 모델의 실험을 통해 수정된 IDD 기법이 기존의 IDD로 구성되는 내부 피드백에 RS 복호기 기반의 외부 피드백으로 구성된 형태로 피드백 회수가 증가할수록 기존의 IDD에 비해 성능이 개선됨을 확인하였다.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.4
• /
• pp.283-290
• /
• 2009

The rank/select data structure is a basic tool of succinct representations for several data structures such as trees, graphs and text indexes. For a given string sequence, it is used to answer the occurrence of characters up to a certain position. In previous studies, theoretical rank/select data structures were proposed, but they didn't support practical operational time and space. In this paper, we propose a simple solution for implementing rank/select data structures efficiently. According to experiments, our methods without complex encodings achieve nH$_0$ + O(n) bits of theoretical size and perform rank/select operations faster than the original HSS data structure.

• Korean Journal of Ichthyology
• /
• v.13 no.4
• /
• pp.223-229
• /
• 2001

Feeding habits of juvenile Sillago maculata, collected from the tropical seagrass beds in Cockle Bay, Queensland, were studied. S. maculata (0.5~9.5 cm SL) was a carnivore which consumed mainly gammarid amphipods, crabs and copepods. Its diets included small quantities of polychaetes, shrimps, fishes, isopods and cumacean. S. maculata showed ontogenetic changes in feeding habits. Small individuals preyed mainly on copepods, crab larvae and gammarid amphipods. While the portion of the stomach contents attributable to polychaetes, crabs and fishes increased with increasing fish size, consumption of copepods and crab larvae decreased progressively. Gammarid amphipods were the most selected prey item for all size classes.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.6
• /
• pp.79-88
• /
• 1989

In this paper, linear octree is used to reconstruct and to modify the 3-dimensional image from 2-dimensional cross sections provided by computed tomography. Linear octree introduces a considerable data saving of the memory storage required by small computer system. This structure allows the hidden surface removal utilizing the spatial presortedness of hierarchical octree structure and implementation of graphical operations that include viewing transform and shading. An actual human organ is used to illustrate this technique and its implications for theraphy and surgical planning.

• Journal of the Ergonomics Society of Korea
• /
• v.26 no.4
• /
• pp.49-56
• /
• 2007

Handles on objects are very important to increase the safety and efficiency of manual handling of people who use them. In this study, four different prototype cartons combined with auxiliary handles were designed to determine the optimal handle position of cartons through the evaluation of user preferences. Twenty male students are participated in the experiment. Likert-5 point summated rating method was applied to evaluate the user preferences for provided handles of the carton among upper, middle, and lower position under the four different sizes and materials handling conditions(carrying positions). The results show that the subjects preferred upper part of the handle on the small cartons regardless of the carrying positions while upper and middle parts of the handle on the big cartons for handling above the waist height were preferred. An optimal handle position depending on the different sizes of carton and the different carrying positions were recommended based on the results of evaluation. It is thus recommended that the cartons provide handles on its relevant position depending on the size and materials handling condition to reduce the musculoskeletal stress and in turn to increase the user satisfaction.

• Korean Journal of Ichthyology
• /
• v.10 no.2
• /
• pp.176-183
• /
• 1998

Spawning ecology and feeding habits of Maurolicus muelleri in the Korean waters were studied. M. muelleri spawned continuously throughout the year showing a peak in August. Major spawning ground of this species was the southeastern sea of Korea. The fecundity observed from the ovaries of M. muelleri showed a range of 5,072 to 32,117, and the average number of eggs per one spawning time was approximately 250. M. muelleri was a zooplanktivore which fed mainly on copepods. Its diets also included various crustaceans such as amphipods, euphausiids, shrimps and mysids.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.134-134
• /
• 2010

KBSI 부산센터에 건설중인 소형의 다중 양전하 중이온 가속기에 사용될 초전도 ECR 이온온은 최대 자기장 3 T, 최소 0.5 T의 자기 Mirror구조를 가지고 있으며 중심 부근의 1 T 자기장에서 28 GHz 전자공명에 의해 마이크로파의 에너지를 플라즈마로 전달한다. 최대 10 kW의 Gyrotron에서 TE02 모드로 발생하는 마이크로파는 모드변환기, 직류차단기 및 진공창을 통하여 플라즈마로 입사된다. 32.5 mm 지름의 원형 도파관에서 자기장 축방향으로 도입된 TE01 모드의 마이크로파를 Altar-Appleton-Hartree 분산관계식을 이용하여 군속도의 관점에서 살펴보았다. 플라즈마 밀도가 Cut-off에 근접하지 않는 한 마이크로파의 바깥 방향으로의 회절은 크지 않았으며, 전자공명 위치로 접근함에 따라 군속도의 방향이 바뀌어 오히려 중심 방향으로 향함을 알 수 있다. 즉 마이크로파가 플라즈마 챔버의 벽을 가열시킬 가능성은 크지 않은 것이다. 또한 뜨거운 전자 플라즈마의 Susceptibility를 이용하여 마이크로파의 플라즈마로의 전자 공명에 의한 흡수를 살펴본 결과, 운전 영역에 속하는 전자밀도가 제공되면 공명 지점에 이르기 전에 충분히 흡수되는 것을 확인하였으며, 이에 따라 챔버를 관통하여 인출부 벽에 충돌하는 마이크로파 에너지는 무시할 수 있을 것으로 보여진다. 이 결과들을 토대로 마이크로파 시스템을 설계 완료하였다.