• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.345-358
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• 2019

The purpose of this study is to develop the Internet vulnerability index of adolescents. To do this, we used the original data of long - term follow - up survey for the internet overdependency cause analysis conducted by NIA in 2018, and analyzed the correlation between alternatives of internet vulnerability index and personal psychology by using linear regression analysis. Factor analysis showed that the relationship with the surroundings was indexed by adding 9 items to positive factors such as family acceptance, peer attachment, and teacher favorability. The relationship between the surroundings and self - stigmatization is confirmed, and the relationship between the surroundings and the Internet fragility is predicted to be negatively related, and the digital capacity is also assumed to be negatively correlated with the Internet vulnerability. In order to develop the specific form of the Internet vulnerability index, personal psychology and linear regression analysis were conducted. As a result, positive factors and R value of personal psychology were increased when considering the relationship with the environment and the digital capacity rather than the Internet overdependency model. Based on these implications, we discussed the implications and limitations of this study.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.2
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• pp.71-78
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• 2012

The digital tachograph is a device that automatically records speed and distance of a vehicle, together with the driver's activity and vehicle status at an accident. It records vehicle speed, break status, acceleration, engine RPM, longitude and latitude of GPS, accumulated distance, and so on. European Commission regulation made digital tachographs mandatory for all trucks from 2005. Republic of Korea made digital tachographs mandatory for all new business vehicles from 2011 and is widening the range of vehicles that must install digital tachographs year by year. This device is used to analyze driver's daily driving information and car accidents. Under a car accident that makes the device reliability unpredictable, it is very important to store driving information with maximum reliability for its original mission. We designed and implemented a practical digital tachograph. This paper presents a storage scheme that consists of a first storage device with small capacity at a high reliability and a second storage device with large capacity at a low cost in order to reliably records data with a hardware at a low cost. The first storage device records data in a SLC NAND flash memory in a log-structured style. We present a reverse partial scan that overcomes the slow scan time of log-structured storages at the boot stage. The scheme reduced the scan time of the first storage device by 1/50. In addition, our design includes a scheme that fast stores data at a moment of accident by 1/20 of data transfer time of a normal method.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.13-21
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• 2019

Purpose : The purpose of this study was to investigate the effect of abdominal muscle strengthening exercise on abdominal muscle strength and respiratory function in stroke patients. Methods : The subjects were 14 stroke patients (10 males, 4 females) hospitalized at W rehabilitation hospital in Busan City and randomly assigned to 7 exercise groups and 7 control groups. Exercise was performed in combination with an upper and lower extremity pattern of proprioceptive neuromuscular facilitation. Measurements of abdominal muscle strength and respiratory function were made before intervention and 4 weeks after intervention. Abdominal muscle strength was assessed using a digital manual dynamometer, and respiratory function was assessed by spirometry. The collected data were analyzed with a paired t-test and independent t-test and the significance level was set as α =.05. Results : The results showed that applying abdominal muscle strengthening exercise to stroke patients showed a significant increase in abdominal muscle strength and a significant difference between groups (p<.05). Maximal-effort expiratory spirogram (MES) readings were significantly increased in forced vital capacity (FVC), and forced expiratory volume in one second (FEV₁), in the exercise group, and there were a significant differences between the groups in terms of FEV1 (p<.05). Slow vital capacity (SVC) was significantly increased in vital capacity (VC), tidal volume (TV), inspiratory reserve volume (IRV), and expiratory capacity (EC), and there were significant differences between the groups in VC, TV, expiratory reserve volume (ERV), EC, and inspiratory capacity (IC) (p<.05). Conclusion : Abdominal muscle strengthening exercise was effective in the abdominal muscle strength of stroke patients, and it was confirmed to have a positive effect on the enhancement of respiratory function. Therefore, it seems that exercise programs for stroke patients with respiratory weakness should include abdominal muscle strengthening exercises.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.288-288
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• 2013

Lithium-ion battery (LIB) is one of the most important rechargeable battery and portable energy storage for the electric digital devices. In particular, study about the higher energy capacity and longer cycle life is intensively studied because of applications in mobile electronics and electric vehicles. Generally, the LIB's capacity can be improved by replacing anode materials with high capacitance. The graphite, common anode materials, has a good cyclability but shows limitations of capacity (~374 mAh/g). On the contrary, silicon (Si) and germanium(Ge), which is same group elements, are promising candidate for high-performance LIB electrodes because it has a higher theoretical specific capacity. (Si:4200 mAh/g, Ge:1600 mAh/g) However, it is well known that Si volume change by 400% upon full lithiation (lithium insertion into Si), which result in a mechanical pulverization and poor capacity retention during cycling. Therefore, variety of nanostructure group IV elements, including nanoparticles, nanowires, and hollow nanospheres, can be promising solution about the critical issues associated with the large volume change. However, the fundamental research about correlation between the composition and structure for LIB anode is not studied yet. Herein, we successfully synthesized various structure of nanowire such as Si-Ge, Ge-Carbon and Si-graphene core-shell types and analyzed the properties of LIB. Nanowires (NWs) were grown on stainless steel substrates using Au catalyst via VLS (Vapor Liquid Solid) mechanism. And, core-shell NWs were grown by VS (Vapor-Solid) process on the surface of NWs. In order to characterize it, we used FE-SEM, HR-TEM, and Raman spectroscopy. We measured battery property of various nanostructures for checking the capacity and cyclability by cell-tester.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3701-3727
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• 2016

Recently Service Function Chaining (SFC) is promising to innovate the network service mode in modern networks. However, a feasible implementation of SFC is still difficult due to the need to achieve functional equivalence with traditional modes without sacrificing performance or increasing network complexity. In this paper, we present a configurable network service chaining (CNSC) mechanism to provide services for network traffics in a flexible and optimal way. Firstly, we formulate the problem of network service chaining and design an effective service chain construction framework based on integrating software-defined networking (SDN) with network functions virtualization (NFV). Then, we model the service path computation problem as an integer liner optimization problem and propose an algorithm named SPCM to cooperatively combine service function instances with a network utility maximum policy. In the procedure of SPCM, we achieve the service node mapping by defining a service capacity matrix for substrate nodes, and work out the optimal link mapping policies with segment routing. Finally, the simulation results indicate that the average request acceptance ratio and resources utilization ratio can reach above 85% and 75% by our SPCM algorithm, respectively. Upon the prototype system, it is demonstrated that CNSC outperforms other approaches and can provide flexible and scalable network services.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.336-339
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• 2003

A digital data logging system has been developed for the purpose of a compact offline Ocean Bottom Seismometer(OBS). The Digital Data Logger(DDL) consists of A/D system, Micom with storage memory and firmware managing data files. The A/D system acquires data of 16bit/4ch with sampling rate of 250Hz per channel. The Micom, a micro controller board with T33521 processor of 8051 class, was equipped with 8 flash memories of 128MB for data storage capacity of 1GB. The firmware stores the acquiring data in form of binary files. The DDL was designated to be compact and light and to consume low energy as possible. The DDL is to interface with PC through USB(Universal Serial Bus). The performance of the DDL has been validated through tests with respect to a 3-axis seismometer.

• Journal of Internet Computing and Services
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• v.6 no.3
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• pp.1-16
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• 2005

This paper propose not only MDIT(Mobile Digital Investment Trust) agent design for Trust Investment under Mobile E-commerce environment, but also the symmetric key algorithm 3BC(Bit, Byte and Block Cypher) and the public encryption algorithm F2mECC for solving the problems of memory capacity, CPU processing time, and security that mobile environment has. In Particular, the MDIT Security Agent is the banking security project that introduces the concept of investment trust in mobile e-commerce, This mobile security protocol creates a shared secrete key using F2mECC and then it's value is used for 3BC that is block encryption technique. The security and the processing speed of MDIT agent are enhanced using 3BC and F2mECC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.288-299
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• 1996

The co-channel digital radio-relay system improves effectively the use of radio frequency allocations by transmitting signals separately on both orthogonal allocations, and thereby not only the total transmission capacity of frequency band but also its bandwidth effciency are almost doubled, compared tothe interleaved digital radio-relay system. Therefore, the study on the development and application of the con-channel scheme is of importance, for the efficient use of limited frequency bnad. In this paper, we derived the eqations for calculating fade margin as a function of path length as well as error performance in terms of the outage probability for co-channel digital radio-relay system below 10GHz. And, simulation was given to demonstrate how to apply those equations to the real situation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.201-208
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• 2005

This study presents the experimental study on improvement of frost/defrost performance in an heat pump system with newly developed fin and multiple compressors. As multiple compressors system, the variable and single speed compressor combinations has been introduced and compared with single speed 1-compressor system in a view point of improvement of frost/defrost performance. Also, newly developed corrugate shaped fin has been compared with conventional louver shaped fin. The frost/defrost performance is defined and some parameters are compared to discuss the effect of each combination. From this experimental study, it is known that if the variable and single speed compressor combination system equipped with corrugate shaped fin, the system performance has greatly improved not only for heating capacity, but also for frost performance.

• Journal of Digital Convergence
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• v.9 no.5
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• pp.215-224
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• 2011

The purpose of this study is to identify a core competencies of the smart worker which most needed in the Smart Work 2.0 environment and to define the competence model of smart worker that can be most applied to. Smart worker for the core competence model as a originality & innovation competence and social skills, digital capability and the capacity of each organic connection to each other is very necessary. Such a smart worker competencies needed to strengthen the three related to the smart foundation for a smart network that will help encourage a very important role is considered.