• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.7-11
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• 2014

In this paper, we designed resistive MMIC mixer using $0.5{\mu}m$ p-HEMT process. This Mixer is designed to have a similar performance in -4 ~ 4 dBm local oscillator signal power level and to maintain a constant conversion loss and linear performance due to the variation of local signal. In order to have such characteristics, we designed new feedback circuit topology by using FET, and minimized performance change for LO signal power level variation, also obtain MMIC mixer characteristics which is able to apply in wideband. In the design result, When the LO signal power is -4 ~ 4 dBm, there was 6 dB conversion loss and it came up with the excellent result that IIP3 got over 30 dBm in 0.5 ~ 2.6GHz frequency band.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.723-732
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• 2022

The success of enterprise information system(EIS) is crucial to align with corporate strategies and eventually attain corporate goals. Since one of the factors to information system success is system use, managerial efforts to measure the level of EIS utilization is vital. In this paper, the EIS utilization level is analyzed using system access log data. In particular, process sequence patterns and clustering of similar functions are identified in more detail based on a process mining method, in addition to basic access log statistics. The result of this research can be used to improve existing information system design by finding real IS usage sequences and function clusters.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.67-68
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• 2022

본 논문에서는 온라인 비대면 교육환경에서 메타버스 플랫폼을 활용한 게임제작프로젝트의 PBL(Project-Based Learning) 교수법 운영방법을 예시를 통해 제시한다. 본 연구에서는 C 대학교 게임전공의 2, 3학년 학생들이 수강한 게임제작프로젝트 관련 수업에 게더타운 메타버스 픝랫폼을 활용한 비대면 PBL 교수법을 적용하였다. 이 수업을 위해 게더타운 플랫폼에 실제 실습실 및 작업공간과 유사한 환경을 2D 디지털 가상세계를 구축하였고, 이 플랫폼에서 오리엔테이션, 팀빌딩, 프로젝트 진행 및 피드백 등 PBL 교수법을 적용하였다. 게더타운 플랫폼을 활용한 PBL 교수법 적용 결과 최종 산출물의 퀄러티는 기존 대면으로 진행했을 때와 크게 다르지 않았음을 확인하였다.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.213-226
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• 2008

E. H. KIM, E. S. CHOI, D, H. NAM, S. S. KIM, J. W. CHUNG and T. W. KIM, The Instrumenfal Development for Pulling . Reaping Training & Measuring in Judo.Korean Jiurnal of Sport Biomechanics, Vol. 18, No. 1, pp. 213-226, 2008. The purpose of this study was to develop a judo-doll uke(partner : doll-uke) for training and measurement applicable to pulling, pushing and reaping in judo. In Judo the most common techniques consist of the pulling, pushing and sweep which all need to be practiced with a partner. So the research needs to develop a measurement system that can be used to evaluate the forces involved with these techniques. Also the Doll-Uke must be developed so that judokas can train alone. After the manufacture of Doll-Uke the usefulness of it must be evaluated. The height of a Doll-Uke is l70cm and its weight is 50kg. Doll-Uke was developed with a trunk angle of 55 and the lower extremities of an angle of 45. The Doll-Uke can also measure the forces developed during the pulling, pushing and sweep. Due to the ability of the system to measure the forces while preforming Judo techniques feedback can be provided to the Judokas to improve their performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1285-1294
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• 1999

In this paper we consider the performance of TCP video traffic over ABR with Long-Range Dependent VBR traffic. As compressed coded video traffics are increasing rapidly over Internet, lots of studies are being done for transmitting those traffics efficiently using limited network resources. We consider here the transmitting video service over ABR service in ATM networks, especially satellite networks. CBR or VBR services are suggested in transmitting the video traffic in ATM Forum TM 4.0. But ABR service connection, which is considered as appropriate service for data traffic, can be established with a small amount of bandwidth, MCR (Minimum cell rate). Furthermore ABR service can control the source's transmitting rate using feedback mechanism. Using this feature ABR service can be used in some applications which can control their quality of services corresponding to network loads. Compressed video sources with MPEG-2 are used for Long-Range Dependent VBR traffic here. We model the compressed video source to resemble the MPEG-2 transport streams. These compressed video traffic streams are consisted of three different frames, I-frame, P-frame, and B-frame. So when a network are overloaded, we can control the quality of service using this traffic features. TCP Traffics over ABR need large buffers in ATM switch to satisfy their QoS with background VBR traffics, which have high deviations in bandwidth. Furthermore satellite ATM networks with large feedback delay need large buffers corresponding RTT delay. The performance comparisons among EFCI and ER switch (ERICA+) switches in the network circumstances described above were shown in this paper. We also considered the case with ON-OFF VBR traffics.

• Journal of KIISE:Databases
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• v.33 no.4
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• pp.372-383
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• 2006

Among the approaches to image database management, content-based image retrieval (CBIR) is viewed as having the best support for effective searching and browsing of large digital image libraries. Typical CBIR systems allow a user to provide a query image, from which low-level features are extracted and used to find 'similar' images in a database. However, there exists the semantic gap between human visual perception and low-level representations. An effective methodology for overcoming this semantic gap involves relevance feedback to perform feature re-weighting. Current approaches to feature re-weighting require the number of components for a feature representation to be the same for every image in consideration. Following this assumption, they map each component to an axis in the n-dimensional space, which we call the metric space; likewise the feature representation is stored in a fixed-length vector. However, with the emergence of features that do not have a fixed number of components in their representation, existing feature re-weighting approaches are invalidated. In this paper we propose a feature re-weighting technique that supports features regardless of whether or not they can be mapped into a metric space. Our approach analyses the feature distances calculated between the query image and the images in the database. Two-sided confidence intervals are used with the distances to obtain the information for feature re-weighting. There is no restriction on how the distances are calculated for each feature. This provides freedom for how feature representations are structured, i.e. there is no requirement for features to be represented in fixed-length vectors or metric space. Our experimental results show the effectiveness of our approach and in a comparison with other work, we can see how it outperforms previous work.

• Journal of KIISE:Databases
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• v.30 no.5
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• pp.507-520
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• 2003

In this paper, an automatic construction method of theme melody index for large music database and an associative content-based music retrieval mechanism in which the constructed theme melody index is mainly used to improve the users' response time are proposed. First, the system automatically extracted the theme melody from a music file by the graphical clustering algorithm based on the similarities between motifs of the music. To place an extracted theme melody into the metric space of M-tree, we chose the average length variation and the average pitch variation of the theme melody as the major features. Moreover, we added the pitch signature and length signature which summarize the pitch variation pattern and the length variation pattern of a theme melody, respectively, to increase the precision of retrieval results. We also proposed the associative content-based music retrieval mechanism in which the k-nearest neighborhood searching and the range searching algorithms of M-tree are used to select the similar melodies to user's query melody from the theme melody index. To improve the users' satisfaction, the proposed retrieval mechanism includes ranking and user's relevance feedback functions. Also, we implemented the proposed mechanisms as the essential components of content-based music retrieval systems to verify the usefulness.

• Journal of Intelligence and Information Systems
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• v.13 no.1
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• pp.1-14
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• 2007

Character images for the background screen of cell phones are one of the fast growing sectors of the mobile content market. However, character image buyers currently experience tremendous difficulties in searching for desired images due to the awkward image search process. Content-based image retrieval (CBIR) widely used for image retrieval could be a good candidate as a solution to this problem, but it needs to overcome the limitation of the mobile Internet environment where an initial query set (IQS) cannot be easily provided as in the PC-based environment. We propose a new approach, IQS-AutoGen, which automatically generates an initial query set for CBIR on the mobile Internet. The approach applies the collaborative filtering (CF), a well-known recommendation technique, to the CBIR process by using users' preference information collected during the relevance feedback process of CBIR. The results of the experiment using a PC-based prototype system show that the proposed approach successfully satisfies the initial query requirement of CBIR in the mobile Internet environment, thereby outperforming the current image search process on the mobile Internet.

• Journal of vocational education research
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• v.37 no.3
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• pp.65-83
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• 2018

In this study, we want to analyze the aspect that required in the classroom for the operation of NCS-based curriculum, the interest of specialized subject teachers on implementable teaching and learning methods. As a result, the overall interest in teaching-learning method of specialized subject teachers was similar to that of non-user patterns among four types of interest patterns. In other words, specialized subject teachers want to know more about teaching-learning method for applying NCS-based curriculum, but we are only aware of the general facts at present, and it seems that there is low interest in actual operation. In addition, there was no statistically significant difference in the degree of interest in the teaching-learning method according to general variables(gender, related training experience, career, and curriculum group) of the specialized subject teachers. The specialized subject teachers are not well aware of the influence of the teaching-learning method according to the introduction of NCS-based curriculum, and to that end, there was little interest in collaboration with colleagues.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.181-192
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• 2015

Nonverbal immediacy plays a key role in interpersonal communication, inducing closeness and another interaction. This case study investigates the nonverbal behaviors in Human-Robot Interaction(HRI) focusing on immediacy, and how they affect perception of a robot. The results show that nonverbal immediacy, such as nodding and leaning forward, affect perceived interactivity. Nonverbal immediacy can be interpreted their meaning clearly when verbal feedback or other communication channel reinforcing them. Also, touch is found to affect come up with similar ones to the robot, because it is associated with concrete and discrete context. People tend to apply social rules to the robot, but they are more open to the unfamiliar robot compared to strangers. The findings in this study provide future HRI studies with heuristic implications by showing a direction and clarifying principles for composition of verbal and nonverbal expression.