• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.700-709
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• 2007

The heterogeneous wireless access networks has been envisioned to characterize the future wireless networks. In such environments, TCP(Transmission Control Protocol) has to experience poor end-to-end performance because bandwidth and link delay change suddenly when a mobile node moves over different types of wireless networks, which is called vertical handoff. In this paper, we propose a new TCP which maintains each set of congestion control variables, which we call TCP context, for each type of wireless network. The proposed TCP can switch the TCP context against vertical handoff in order to adjust quickly to a newly arrived network. In simulations, the proposed TCP has higher throughput than TCP SACK(Selective Acknowledgment Options) due to its great features to vertical handoff situations.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.9
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• pp.28-34
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• 1998

In ATM networks CBR data traffic is sent in constant bit rate, and VBR data traffic in variable bit rate. Therefore unused bandwidth at network capacity may exist. To avoid waste of network resourcesm, ABR traffic utilizes the unused bandwidth to the utmost after CBR and VBR data traffic being first served. In this paper, a transfer rate-based congestion control algorithm is proposed for efficient ABR service in ATM networks. In the proposed algorithm the ATM switch first calculates bandwidth according to variable cell transfer rate in an ABR source. records this value in ER field in a RM cell, and then transmits a RM Cell to an ABR source. In this way the proposed algorithm dynamically allocates bandwidth to each ABR source, and the switch also can rapidly adapt to a change of a transfer rate of an source. The performance simulation of the proposed algorithm has batter performance in terms of source condition and link utilization.

• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1663-1669
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• 2018

Pair programming is a software development technique in which two programmers work together at one computer. One writes code while the other reviews the code, and they switch roles frequently. Pair-programming practice in school programming lab is expected to improve the learning performance, provide collaboration experience, and promote interactions between students. This work finds out how students accept pair-programming, what make students reluctant to join pair-programming by repeated questionnaire surveys in a college programming lab class. Based on these findings aome guidelines for school pair-programming are provided. First, students should be allowed to choose to do pair-programming or not. Second, various obstacles that make students hesitate to switch roles should be removed. Third, the pair matching should be made with great care.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.3
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• pp.395-407
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• 2008

As global interest in clothing spreads over the smart clothing which arouses high added-value in the apparel industry, this study is to develop a smart jacket with an electrically-vibrating device maintaining excellent appearance and comfort. The vibrating device has a massage function that could relieve muscle pain near shoulders and neck. The purposes of this research are to develop jacket pattern for men in their thirties considering body shapes and fashion trend, to develop a wearable device that is composed of motor and controller and integrate it into a jacket, and to assess the external appearance and functional satisfaction of the smart jacket through the wearing test. The results are as follows: 1. In order to develope an appropriate jacket pattern for men in their thirties, several patterns were assessed for their fitting comfort. The final pattern was completed after making alterations some parts, and showed high satisfaction as 3.6(on a five-point scale) in all categories. 2. A vibrating device was developed by connecting motor, controller, battery and switch. Developing this device, focus was maximizing the strength of motor and minimizing the heat generated from motor and controller. Snaps were placed between inner and outer cloth of jacket so that the vibrating device could be easily attachable and detachable. The motor was located around Trapezius where muscles often get stiff. A switch was designed to be used in selecting the modes of Strong, Weak, and Cross Tapping. 3. The wearing test was conducted to examine outer appearance, comfort for motion, and functionality of the smart jacket. The results of assessing outer appearance showed that the location for attaching the vibrating device was not noticeable but looked natural, and there is almost no change in outer appearance when the vibrating device operates. The result of assessing comfort of action revealed that wearer's satisfaction was high in all categories about activity, wearer's comfort, etc. The result also showed that wear's satisfaction for effects of vibrating massage, easiness in using the device, heat generation was not less than 3.5 in all categories except a category about noise.

• Health Policy and Management
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• v.24 no.1
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• pp.24-34
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• 2014

Background: Bankrupted households have recently been increased due to excessive medical expenditure in Korea. They have not been protected from economic risk when household's member has severe diseases that need a lot of money for treatment. Purpose of this study examines policy effect by comparing unmet needs' change of policy object households and non-object groups. Methods: We used Korea Health panel 2nd 4th data collected by Korea Institute for Health and Social Affairs and National Health Insurance Service. Analysis subjects were 381 households (pre-policy) and 393 households (post-policy) that had cancer and cardiovascular and cerebrovascular diseases. Since it was major concern that estimates benefit strengthening policy started by certain time, we setup comparing households which had diabetes, hypertension disease. Comparison subjects were 393,247 households, respectively and we evaluated policy effect using difference in difference (DID) model. Results: Although unmet needs of policy object households were higher than non-object groups, policy execution variable affected negative direction. But interaction-term which shows pure effect of policy was not statistically significant. We utilized multi-DID model to examine factors affecting unmet needs causes. Copayment assistance policy did not significantly affect households that responded to 'economic reason,' and 'no have time to visit' for unmet needs causes. Conclusion: The second copayment assistance policy did not significantly give positive effect to beneficiary households than non-beneficiary groups. When we consider that primary purpose of public insurance guarantee high medical expenditure occurred by unexpected events, it needs to deliberate on switch of benefit strengthening policy that can assist vulnerable people. Also, we suggest that government forward a policy covering non-reimbursable medical expenses as well as switch of benefit strengthening direction because benefit policy do not affect non-covered medical cost which accounts for quarter of total health expenditure.

• Journal of Practical Engineering Education
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• v.8 no.1
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• pp.9-14
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• 2016

Depending on the college graduation project and graduation thesis regulations for the certification and graduation requirements, the quadcopter acting as a Li-Po battery that charges by solar energy are proposed a design method and improvements in theory. Quadcopter posture is balanced and confirmed by the position sensor, through a PID (Proportional Integral Differential) control. Battery switching circuit is composed of two Li-Po battery. Driving the quadcopter as one battery, and does not use other battery is charged by solar energy. A battery switching circuit is fabricated in a manner that uses two types of relays. Even if completely not charged to the battery is being driven a certain switch by the battery charging voltage from time to time, it proposes a method for increasing the endurance time and range.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.743-752
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• 2020

The purpose of this study was to estimate the economic evaluation of a smart farm investment for tomatoes and strawberries. In addition, the potential adoption rate of the smart farm was derived for different scenarios. This study analyzed the economic evaluation with the net present value (NPV) method and estimated the adoption potential of the smart farm with the trade-off analysis, minimum data (TOA-MD) model. The results were as follows: The analysis of the net present value shows that the smart farm investment for the two crops are economically feasible, and the minimum prices for the tomatoes and strawberries should be 1,179 and 3,797 won/kg to secure a sufficient economic feasibility for the smart farm investment. Next, the analysis of the potential adoption rates for smart farms through the TOA-MD model showed that when the support ratio for the adoption of a smart farm system was 50% and the price increase rates were, respectively, - 5, 2.5, 0, 2.5, and 5%, the conversion rates for tomato farms to switch to smart farms were 0.97, 1.78, 3.05, 4.91, and 7.47%, while the ratios of the strawberry farms to switch to smart farms were 0.12, 0.29, 0.65, 1.33, and 2.53%, respectively. This study has some known limitations, but it provides useful information on decision making about smart farm adoption and can contribute to government policies on smart farms.

• Textile Coloration and Finishing
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• v.34 no.3
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• pp.207-216
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• 2022

Hydrogels have gained considerable attention in various fields due to their easily transformative ability by different stimulation. In addition, metal-based conductive additives can enable the hydrogels to be conductive with dimension change. Although the development of the additives offered enhanced electrical properties to the hydrogels, correspondingly enhanced mechanical properties may limit the volume and electrical properties switching after stimulation. Here we prepared poly(N-isopropylacrylamide) (PNIPAM) thermo-responsive hydrogel that has a 32℃ of low critical solution temperature and added liquid metal particles (LMPs) as conductive additives, possessing soft and stretchable benefits. The LMPs enabled PNIPAM (PNIPAM/LMPs) hydrogels to be constricted over 32℃ with a high volume switching ratio of 15.2 when deswelled. Once the LMPs are spontaneously oxidized in hydrogel culture, the LMPs can release gallium ions into the hydrogel nature. The released gallium ions and oxidized LMPs enhanced the modulus of the PNIPAM/LMPs hydrogel, triggering high mechanical stability during repeated swelling/deswelling behavior. Lastly, highly constricted PNIPAM/LMPs hydrogel provided a 5x10⁶ of electrical switching after deswelling, and the switching ratio was closely maintained after repeated swelling/deswelling transformation. This study opens up opportunities for hydrogel use requiring thermo-responsive and high electrical switching fields.

• Journal of Information Technology Applications and Management
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• v.30 no.2
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• pp.45-57
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• 2023

Efforts to build metaverse platform services and expand profit structure are developing in a more realistic direction. The metaverse, which has been centered on 'creation and economy' and 'discovery', will evolve into an 'experience' metaverse, creating tangible business effects where satisfaction with the user experience leads directly to purchase. In this paper, the condition of the avatar used as a medium of economic activity between the metaverse platformer and the user and the business utilization plan were sought. In addition, a new 'metaverse business model' was proposed based on 'experience, discovery, creation and economy', and in particular, it was intended to lay the foundation for the experience metaverse to further develop in the form of 'business experience'. In addition, a survey was conducted on the 'application of metaverse service and avatar' targeting the MZ generation, the main customer base of the current metaverse service. In order to provide a service that satisfies the user, it was concluded that the appearance of the avatar needs to be changed according to the purpose and function. Accordingly, we propose an 'selective switch mode' that can change the avatar's appearance at the desired timing according to the 'experience' and 'purchase purpose' of each metaverse service area. In addition, by strategically utilizing the 'Digilog' psychology, we believe that it will be possible to promote the influx of new users while increasing the loyalty of existing users to the platform. Through the establishment of 'avatar purchase system' by 'selective switch mode' and 'avatar decorating system' by 'digilog' strategy, the experience metaverse, which has been focused on 'digital twin experience' so far, is As it develops into 'business experience', it is expected that the user experience can be further satisfied.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.4
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• pp.143-149
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• 2011

The experiment has been investigated the room temperature change under adjusting 4-way valve which was installed for cooling and heating switch. Beside, the temperature of heat pump was controlled automatically for autonomously adjusting temperature and maintaining a constant room temperature. As results, Inlet & outlet temperature differences of compressor are $95^{\circ}C$ in cooling condition and $57^{\circ}C$ in heating condition. Therefore, Compression efficiency of cooling effect is higher than heating effect. In addition, Heat exchange effect of Cooling system condition is higher than heating system. This results can be used for studying about automatic temperature control of cooling and heating system with heat pump and 4way valve.