• Journal of KIISE:Information Networking
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• v.30 no.4
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• pp.494-503
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• 2003

The IEEE 1394 High Speed Serial Bus is a versatile, high-performance, and low-cost method of promoting interoperability between all types of A/V and computing devices. IEEE 1394 provides two transfer modes: asynchronous mode for best effort service and isochronous mode for best effort service with bandwidth reservation. This paper shows the bus performance and compared the transfer odes first at the link level and then at the application level. For the application level performance, we analyze the bus systems with fixed and adaptive interfaces, applied between the upper layer and the 1394 layer, using polling systems. Also we verifies the analysis models with simulation studies. Based on our analysis, we conclude that the adaptive interface reduces the bus access time and so increases the bus utilization.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.41.3-41.3
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• 2019

To find out the origin and formation mechanism of LASCO-C2 post-CME blobs, we investigate 2 LASCO-C2 blobs and 35 low corona blobs observed by K-Cor on 2017 September 10 from 17:11 to 18:58 UT. By visual inspection of a post-CME ray and the locations of low corona blobs in K-Cor and LASCO-C2 images with examining the time-height data of all blobs, we find the following results: (1) The post-CME ray structure is well identified in the K-Cor images than LASCO-C2 ones. (2) Low corona blobs can be classified into two groups according to their formation mechanisms: 27 blobs belong to Group 1, generated by the tearing mode instability near the middles of current sheets as described by Furth et al., 1963; Shibata & Tanuma, 2001; Shen et al., 2011, the others belong to Group 2, formed by the tearing mode instability near the tips of current sheets as shown in Figure 5 of Sitnov et al., 2002. (3) Group 1 has low initial appearance heights <1.30 Rs>, broad speed range (38 ~ 945 km/s), and high accelerations <4,272 m/s² > than Group 2, which has initial appearance heights <1.72 Rs>, speed range (579 ~ 843 km/s), and accelerations <1,413 m/s² >. (4) among 8 blobs for Group 2, only 2 blobs are temporally and spatially associated with 2 LASCO-C2 ones and their initial observation heights are 1.93 and 1.79 Rs, respectively. Our results firstly demonstrate that LASCO-C2 blobs form the heights from about 1.7 to 2.0 Rs and they are generated by the tearing mode instability near the tips of current sheets.

• Physical Therapy Rehabilitation Science
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• v.13 no.2
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• pp.205-212
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• 2024

Objective: The purpose of this study is to confirm the exercise effect when combining wearable exercise assist robot, Bot fit's resist mode (Samsung Electronics) and stair climbing. Design: Cross-section study Methods: Targeting 53 adults and seniors, foot pressure and muscle activity were measured when climbing 3-story stairs using foot pressure measurement equipment (W-insole Science System) and surface muscle activity measurement equipment (sEMG; FreeEMG, BTS Bioengineering, Italy) using Bot Fit's resist mode. All subjects were measured without wearing Bot Fit, and the data between the two conditions were compared and analyzed. Results: The front area(p<0.01) and middle area(p<0.05) foot pressures of adults significantly increased when wearing the Bot fit. Frontal area foot pressure significantly increased in elderly people with knee arthritis and obesity(p<0.05). The gastrocnemius activity in all subjects significantly decreased after wearing Bot Fit(p<0.01). In elderly people with knee arthritis, the muscle activity of the rectus femoris was significantly reduced(p<0.05)., and in obese elderly people, the muscle activity of the gastrocnemius muscle was significantly reduced(p<0.05). Conclusions: Based on the results of this study, it is possible to induce correct stair climbing posture when climbing stairs using Bot fit resistance mode. In particular, it is expected to be an effective exercise for strengthening muscle endurance by increasing the activity of the rectus femoris muscle.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.29-36
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• 2005

The crustal structure of Korean Peninsula is investigated by analyzing phase velocity dispersion data of Rayleigh wave. Earthquakes recorded by three component seismographs during 1999 - 2004 in South Korea are used in this study. The fundamental mode signals of Rayleigh waves are obtained from vertical components of seismograms by multiple filter technique method and phase match filter method. Velocity dispersion curves of surface waves for 14 propagation paths on the great circle are computed from the fundamental mode signals on the great circle path by two-station method. Treating the shear velocity of each layer as an independent parameter, phase velocities of Rayleigh wave are inverted. The result models are regarded as average structure for surface wave propagation paths respectively. All the results can be explained by an earth model of the Korean Peninsula comprising crust of shear-wave velocity increasing from 2.8 to 3.25 km/sec from top to 33 km depth and uppermost mantle of shear-wave velocity between 4.55 and 4.67 km/sec.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.701-704
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• 2005

Aquifer Thermal Energy Storage (ATES) can be a cost-effective and renewable geothermal energy source, depending on site-specific and thermohydraulic conditions. To design an effective ATES system having influenced by groundwater movement, understanding of thermo hydraulic processes is necessary. The heat transfer phenomena for an aquifer heat storage are simulated using FEFLOW with the scenario of heat pump operation with pumping and waste water reinjection in a two layered confined aquifer model. Temperature distribution of the aquifer model is generated, and hydraulic heads and temperature variations are monitored at the both wells during 365 days. The average groundwater velocities are determined with two hydraulic gradient sets according to boundary conditions, and the effect of groundwater flow are shown at the generated thermal distributions of three different depth slices. The generated temperature contour lines at the hydraulic gradient of 0.00 1 are shaped circular, and the center is moved less than 5m to the groundwater flow direction in 365 days simulation period. However at the hydraulic gradient of 0.01, the contour center of the temperature are moved to the end of boundary at each slice and the largest movement is at bottom slice. By the analysis of thermal interference data between two wells the efficiency of the heat pump system model is validated, and the variation of heads is monitored at injection, pumping and no operation mode.

• Earthquakes and Structures
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• v.11 no.3
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• pp.387-406
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• 2016

The main purpose of this paper is to determine the dynamic characteristics and the structural stability of the two approach viaducts of the Bosphorus Suspension Bridge under the expected stresses that would be caused during earthquake conditions. The Ortakoy and the Beylerbeyi approach viaducts constitute the side spans of the bridge at two locations. The bridge's main span over the Bosphorus is suspended, whereas they are supported at the base at either end. For the numerical investigation of the viaducts, 3-D computational structural finite element-FE models were developed. Their natural frequencies and the corresponding mode shapes were obtained, analyzed, presented and compared. The performances of the viaducts, under earthquake conditions, were studied considering the P-Delta effects implementing the push-over (POA) and the non-linear time-history analyses (NTHA). For the NTHA, three earthquake ground motions were generated depending on the location of the bridge. Seismic performances of the viaducts were determined in accordance with the requirements of the Turkish Seismic Code for the Earthquake Design of Railways Bridges (TSC-R/2008) and those of Caltrans (CALTRANS-2001) given for Seismic Design of Steel Bridges, separately. Furthermore, the investigation was extended for evaluating the possible need for retrofitting in the future. After the analysis of the resultant data, a retrofit recommendation for the viaducts was presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1229-1248
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• 2016

With the feature of convenience and low cost, remote healthcare monitoring (RHM) has been extensively used in modern disease management to improve the quality of life. Due to the privacy of health data, it is of great importance to implement RHM based on a secure and dependable network. However, the network connectivity of existing RHM systems is unreliable in disaster area because of the unforeseeable damage to the communication infrastructure. To design a secure RHM system in disaster area, this paper presents a Secure VANET-Assisted Remote Healthcare Monitoring System (SVC) by utilizing the unique "store-carry-forward" transmission mode of vehicular ad hoc network (VANET). To improve the network performance, the VANET in SVC is designed to be a two-level network consisting of two kinds of vehicles. Specially, an innovative two-level key management model by mixing certificate-based cryptography and ID-based cryptography is customized to manage the trust of vehicles. In addition, the strong privacy of the health information including context privacy is taken into account in our scheme by combining searchable public-key encryption and broadcast techniques. Finally, comprehensive security and performance analysis demonstrate the scheme is secure and efficient.

• Korean journal of communication and information
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• v.16
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• pp.108-135
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• 2001

This study examines the structure of the problems of Korean newspaper reporting raised by the civil society. Based on the differences in the mode of presentation, the problems of newspaper reporting were classified into three types; prominent, associated, and isolate problem. The relations among these problems were defined as the degree of co-occurrence in the monitoring articles. A network analysis was conducted to examine the structure of the problems in Korean newspaper reporting. A $33{\times}33$ similarity matrix of the problems was created by analyzing the data from one monitoring report and two weekly media critics newspapers. The results showed that of the 33 problems, most of them were mentioned as prominent or associated problems. The problems related to the news contents were mostly treated as prominent ones, while the problems about the news writing and reporting styles were frequently treated as associated ones. The network structure of newspaper criticism based on the co-occurrence of 33 problems were divided into six clusters. Among them, the most central was the group including the problems of "unfairness,' "biased interpretation," and "vagueness". In addition, the problems were found to have different roles in the network. Of the 33 problems, two were liaisons and four were attached isolates, indicating the hierarchical structure of problems in newspaper reporting. These results were discussed in the light of two viewpoints; the absence of objective criteria in media criticism, and the need for the comparisons of the current study's results with the opinions of newspaper readers and journalists. finally, the implications for the future studies were presented.

• Journal of Distribution Science
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• v.17 no.1
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• pp.47-56
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• 2019

Purpose - This case study illustrates the story of eBay Korea, which owns two most leading Korean open market companies, AUCTION and Gmarket. The main concerns are to take over the Korean top domestic companies one by one, then, emerge these two giants through its well-developed post-merger Integration by eBay, an American multinational corporation. Research design, data, and methodology - This case explores various secondary resources such as periodicals, annual reviews, magazine, news articles, commentaries, even some interview materials related to 'eBay Korea' and industry source on condition of anonymity based on the critical reviewing of existing studies on these topics as well. Results - The findings of this study show the merger and acquisition of two market leaders in Korea is the only successful case in Asian Markets. The eBay's choice of entry mode is appropriate considering the timing, synergy and efficiency by sharing their resources. Conclusions - This study examines the successful entry and settlement process of foreign, multinational company through mergers and acquisitions in the Korean market. This would be a valuable in the studies of International Business and Global entry or distribution strategy in the e-commerce and open market dealing with M&A and its post-merger integration.

• Nuclear Engineering and Technology
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• v.39 no.4
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• pp.349-358
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• 2007

A single-beam gamma densitometer is utilized to measure the average void fraction in a small diameter stainless steel pipe under critical flow conditions. A typical design of a single-beam gamma densitometer is composed of a sealed gammaray source, a collimator, a scintillation detector, and a data acquisition system that includes an amplifier and a single channel analyzer. It is operated in the count mode and can be calibrated with a test pipe and various types of phantoms made of polyethylene. A good average void fraction is obtained for a small diameter pipe with various flow regimes of the core, annular, stratified, and bubbly flows. Several factors influencing the performance of the gamma densitometer are examined, including the distance between the source and the detector, the measuring time, and the ambient temperature. The void fraction is measured during an adiabatic downward two-phase critical flow in a vertical pipe. The test pipe has an inner diameter of 10.9 mm and a thickness of 3.2 mm. The average void fraction was reasonably measured for a two-phase critical flow in the presence of nitrogen gas.