• Textile Coloration and Finishing
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• v.28 no.1
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• pp.48-56
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• 2016

Improvement of heat sink technology related to the continuous implementation performance and extension of device-life in circumstance of easy heating and more compact space has been becoming more important issue as multi-functional integration and miniaturization trend of electronic gadgets and products has been generalized. In this study, it purposed to minimize of decline of the heat diffusivity by gluing polymer through compounding of inorganic particles which have thermal conductive properties. We used NH-9300 as base resin and used inorganic fillers such as silicon carbide(SiC), aluminum nitride(AlN), and boron nitride(BN) to improve heat diffusivity. After making film which was made from 100 part of acrylic resin mixed hardener(1.0 part more or less) with inorganic particles. The film was matured at $80^{\circ}C$ for 24h. Diffusivity were tested according to sorts of particles and density of particles as well as size and structure of particle to improve the effect of heat sink in view of morphology assessing diffusivity by LFA(Netzsch/LFA 447 Nano Flash) and adhesion strength by UTM(Universal Testing Machine). The correlation between diffusivity of pure inorganic particles and composite as well as the relation between density and morphology of inorganic particles has been studied. The study related morphology showed that globular type had superior diffusivity at low density of 25% but on the contarary globular type was inferior to non-globular type at high density of 80%.

• Journal of KIISE:Software and Applications
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• v.34 no.12
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• pp.1045-1055
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• 2007

Latent topic models are statistical models which automatically captures salient patterns or correlation among features underlying a data collection in a probabilistic way. They are gaining an increased popularity as an effective tool in the application of automatic semantic feature extraction from text corpus, multimedia data analysis including image data, and bioinformatics. Among the important issues for the effectiveness in the application of latent topic models to the massive data set is the efficient learning of the model. The paper proposes an accelerated learning technique for PLSA model, one of the popular latent topic models, by an incremental EM algorithm instead of conventional EM algorithm. The incremental EM algorithm can be characterized by the employment of a series of partial E-steps that are performed on the corresponding subsets of the entire data collection, unlike in the conventional EM algorithm where one batch E-step is done for the whole data set. By the replacement of a single batch E-M step with a series of partial E-steps and M-steps, the inference result for the previous data subset can be directly reflected to the next inference process, which can enhance the learning speed for the entire data set. The algorithm is advantageous also in that it is guaranteed to converge to a local maximum solution and can be easily implemented just with slight modification of the existing algorithm based on the conventional EM. We present the basic application of the incremental EM algorithm to the learning of PLSA and empirically evaluate the acceleration performance with several possible data partitioning methods for the practical application. The experimental results on a real-world news data set show that the proposed approach can accomplish a meaningful enhancement of the convergence rate in the learning of latent topic model. Additionally, we present an interesting result which supports a possible synergistic effect of the combination of incremental EM algorithm with parallel computing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.45-53
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• 2018

Among the various slope stabilization methods, the green soil method based on the growth of plants is advantageous to the environment, but the durability and slope stability are insufficient when the green soil method is applied to a steep slope and rock slope sites. Therefore, in this study, green soil, which improved the adhesion performance and the vegetation environment, was developed using cementitious materials and ECG, and the durability and slope stability as well as the possibility of its use as a rock vegetation base material were assessed. From the results, the adhesive force and internal friction angle were higher than that of the existing green soil so that it could be used for in situ construction. The soil hardness value was 26 mm, which was slightly higher than that of the best growth condition of the plant, 18~23 mm, and the drying shrinkage strain was approximately 3%; hence, it is not expected to affect the durability of green soil. The results of a rainfall intensity simulation for evaluating the slope adhesion force showed that slope failure did not occur under all conditions. The damage decreased with increasing slope angle. Therefore, the green soils developed in this study have excellent durability and slope stability and can be used for rock slope sites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.117-121
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• 2018

As the paradigm shifts in the era of accelerated technological development and technology convergence, the defense sector is pursuing national defense research and development through selection and concentration, as well as the expansion of investments to develop defense science and technology to the highest possible level. In addition to investing heavily in cutting-edge weapons and core technologies that are consistent with the future, the defense sector is also developing investment strategies within a limited budget. In the private sector, the PD system has been introduced in order to maximize the performance of R&D policy and to improve the professionalism and responsibility of planning & management. In accordance with this trend, in the field of defense, the PD system of defense technology with specialization is being promoted, in order to strengthen the task planning capacity and to promote the utilization of private technology. Considering the need for coherent technical support for the core technology developed by R&D, the improvement of open technology planning systems and expansion of inter-civil & technical linkage, the use of the PD system in the defense field is indispensable. In this study, we review similar cases abroad and at home to examine the introduction and management of the PD system for defense technology. This study is based on the current state of the defense technology PD system that is being pursued.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.28-38
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• 2020

Semiconductor deposition equipment is an important example of Complex Products and Systems (CoPS) and requires in-depth understanding of user requirements. For this reason, we analyzed and compared users' and producers' perspectives on the quality attributes of semiconductor deposition equipment using the Kano model. The results show that the patterns of users' perspectives were different from those of producers. Out of 22 level-2 quality attributes, producers evaluated all 22 attributes as attractive qualities, but users evaluated only 6 as "attractive," 10 as "indifferent," 2 as "must have," and 4 as "other." Although all quality attributes were attractive for producers, only those related to reliability were attractive or must-have qualities, and all others were "indifferent." This result implies that the perspectives on quality attributes may be different between users and producers, and producers should revise their perspectives and strategies. In addition, the results support the characteristics of CoPS suggested by literature implying that performance is more important than economies of scale and cost reduction. It is suggested that producers of semiconductor deposition equipment strategize their approaches to users by considering the characteristics of CoPS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7292-7301
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• 2014

With the development of IT Info-Communications technology, the vehicle with a combination of wireless-communication technology has resulted in significant research into the convergence of the component of existing traffic with information, electronics and communication technology. Intelligent Vehicle Communication is a Machine-to-Machine (M2M) concept of the Vehicle-to-Vehicle. The Vehicle-to-Infrastructure communication consists of safety and the ease of transportation. Security technologies must precede the effective Intelligent Vehicle Communication Structure, unlike the existing internet environment, where high-speed vehicle communication is with the security threats of a wireless communication environment and can receive unusual vehicle messages. In this paper, the Vehicle Identification number between the V2I and the secure message communication protocol was proposed using hash functions and a time stamp, and the validity of the vehicle was assessed. The proposed system was the performance evaluation section compared to the conventional technique at a rate VPKI aspect showed an approximate 44% reduction. The safety, including authentication, confidentiality, and privacy threats, were analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.697-703
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• 2017

This paper examines the flexure behavior of FRP-concrete composite structure that can replace conventional reinforced concrete structure types. In order to investigate the structural performance and behavioral characteristics in numerical analysis means, ABAQUS, a general purpose finite element analysis program, was utilized for nonlinear finite element analysis, and the various variables and their influences were analyzed and compared with experimental results to suggest values optimized to this composite structure. The concrete damage plasticity model and Euro code for concrete were used. In the implicit finite element analysis, the convergence was ambiguous when geometrical and material nonlinearity were large, so the explicit finite element analysis used in this study was deemed to be appropriate. From the comparison with the experiment about concrete damaged plasticity model, 20mm for the mesh size, $30^{\circ}$ for the dilation angle, $100Nmm/mm^2$ for the value of fracture energy, 0.667 for Kc value, and the consideration of damage parameter were suggested believed to be appropriate. The numerical model suggested in this study was able to imitate the ultimate load and cracking pattern very well; therefore, it is expected to be utilized in research of various new material composite structures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.437-444
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• 2020

This study was focused on the stabilization of surge motions of a moored vessel under irregular head seas. A two-point moored vessel shows strong non-linearity even in regular sea, owing to its inherent non-linear restoring force. A long-crested irregular wave is subjected to the vessel system, resulting in more complex nonlinear behavior of the displacement and velocities than in the case of regular waves. Sliding mode control (SMC) is implemented in the moored vessel to control both surge displacement and surge velocity. The SMC can provide a closed-loop system with performance and robustness against parameter uncertainties and disturbances; however, chattering is the main drawback for implementing SMC. The goal of minimizing the chattering and state convergence with accuracy is achieved using a quasi-sliding mode that approximates the discontinuous function via a continuous sigmoid function. Numerical simulations were conducted to validate the effectiveness of the proposed control algorithm.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.69-74
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• 2007

Recently, the demands for the satellite broadband mobile communication services are increased. To provide these services, mobile satellite communication systems for the passengers or crews on the high-speed moving vehicles, are being developed for the last several years especially in the Europe and North America. However, most of these systems can provide only several hundred kbps of transmission rate and this is not enough performance to provide satellite internet service for the group users such as passengers on the high-speed train. Moreover, service availability with these systems is limited to be rather low because they don't have any countermeasure scheme for the N-LOS environment which happens often along the railway. This paper describes mobile broadband satellite communication system, which is on the development, to provide high data-rate internet services to the high-speed trains. This system is applied with the inter-networking scenarios of both satellite/terrestrial network and satellite/gap-filler network so that it can provide seamless service even in the train operating environment, and these inter-networking schemes result in high service availability. And this system also has the countermeasure schemes, such as upper layer FEC and antenna diversity, for the short fading which is occurred periodically on the railway due to the power supplying structures so that it can provide high speed internet services. Mobile DVB-S2 technology which is now being standardized in the DVB is used for the forward-link transmission and DVB-RCS for the return-link.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.511-517
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• 2016

Current oil-type potential transformers for trains are filled with insulating oil, which could have problems like explosions due to rising inner pressure during train operation. Therefore, mold and dry-type potential transformers are being developed to prevent explosions. One problem in manufacturing mold-type transformers is preventing void formation around the coiled core inside the mold during epoxy filling, which could cause an electrical spark. Micro voids can remain in the resin after filling, and macro voids can occur due to the structure shape. A transformer that is being developed has a cavity at the junction of the core and the coil for better performance, and when highly viscous epoxy flows inside the cavity channel, macro voids can form inside it. Therefore, in this study, the free-surface flow of the mold filling procedure was analyzed numerically by applying the VOF method. The results were used to understand the phenomena of void formation inside the cavity and to modify the process conditions to reduce voids.