• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1210-1230
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• 1997

In this paper, we suggest an architecture of DS/CDMA tranceiver composed of one pilot channel used as reference and multiple traffic channels. The pilot channel-an unmodulated PN code-is used as the reference signal for synchronization of PN code and data demondulation. The coherent demodulation architecture is also exploited for the reverse link as well as for the forward link. Here are the characteristics of the suggested DS/CDMA system. First, we suggest an interlaced quadrature spreading(IQS) method. In this method, the PN coe for I-phase 1st channel is used for Q-phase 2nd channels and the PN code for Q-phase 1st channel is used for I-phase 2nd channel, and so on-which is quite different from the eisting spreading schemes of DS/CDMA systems, such as IS-95 digital CDMA cellular or W-CDMA for PCS. By doing IQS spreading, we can drastically reduce the zero crossing rate of the RF signals. Second, we introduce an adaptive threshold setting for the synchronization of PN code, an initial acquistion method that uses a single PN code generator and reduces the acquistion time by a half compared the existing ones, and exploit the state machines to reduce the reacquistion time Third, various kinds of functions, such as automatic frequency control(AFC), automatic level control(ALC), bit-error-rate(BER) estimator, and spectral shaping for reducing the adjacent channel interference, are introduced to improve the system performance. Fourth, we designed and implemented the DS/CDMA MODEM to be used for variable transmission rate applications-from 16Kbps to 1.024Mbps. We developed and confirmed the DS/CDMA MODEM architecture through mathematical analysis and various kind of simulations. The ASIC design was done using VHDL coding and synthesis. To cope with several different kinds of applications, we developed transmitter and receiver ASICs separately. While a single transmitter or receiver ASC contains three channels (one for the pilot and the others for the traffic channels), by combining several transmitter ASICs, we can expand the number of channels up to 64. The ASICs are now under use for implementing a line-of-sight (LOS) radio equipment.

• Progress in Medical Physics
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• v.9 no.3
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• pp.127-136
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• 1998

On-line geometrical quality assurance system has been developed using electronic portal imaging system(OQuE). EPID system is networked into Pentium PC in order to transmit the acquisited images to analysis PC. Geometrical QA parameters, including light-radiation field congruence, collimator rotation axis, and gantry rotation axis can be easily analyzed with the help of graphic user interface(GUI) software. Equipped with the EPID (Portal Vision, Varian, USA), geometrical quality assurance of a linear accelerator (CL/2100/CD, Varian, USA), which is networked into OQuE, was performed to evaluate this system. Light-radiation field congruence tests by center of gravity analysis shows 0.2～0.3mm differences for various field sizes. Collimator (or Gantry) rotation axis for various angles could be obtained by superposing 4 shots of angles. The radius of collimator rotation axis is measured to 0.2mm for upper jaw collimator, and 0.1mm for lower jaw. Acquisited images for various gantry angles were rotated according to the gantry angle and actual center of image point obtained from collimator axis test. The rotated images are superpositioned and analyzed as the same method as collimator rotation axis. The radius of gantry rotation axis is calculated 0.3mm for anterior/posterior direction (gantry 0$^{\circ}$ and 170$^{\circ}$) and 0.7mm for right/left direction(gantry 90$^{\circ}$ and 260$^{\circ}$). Image acquisition for data analysis is faster than conventional method and the results turn out to be excellent for the development goal and accurate within a milimeter range. The OQuE system is proven to be a good tool for the geometrical quality assurance of linear accelerator using EPID.

• Korean Journal of Cognitive Science
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• v.16 no.4
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• pp.305-322
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• 2005

Watermarking is a widely employed method tn protecting copyright of a digital image, the owner's unique image is embedded into the original image. Strengthened level of watermark insertion would help enhance its resilience in the process of extraction even from various distortions of transformation on the image size or resolution. However, its level, at the same time, should be moderated enough not to reach human visibility. Finding a balance between these two is crucial in watermarking. For the algorithm for watermarking, the predefined strength of a watermark, computed from the physical difference between the original and embedded images, is applied to all images uniformal. The mean brightness or contrast of the surrounding images, other than the absolute brightness of an object, could affect human sensitivity for object detection. In the present study, we examined whether the detectability for watermark noise might be attired by image statistics: mean brightness and contrast of the image. As the first step to examine their effect, we made rune fundamental images with varied brightness and control of the original image. For each fundamental image, detectability for watermark noise was measured. The results showed that the strength ot watermark node for detection increased as tile brightness and contrast of the fundamental image were increased. We have fitted the data to a regression line which can be used to estimate the strength of watermark of a given image with a certain brightness and contrast. Although we need to take other required factors into consideration in directly applying this formula to actual watermarking algorithm, an adaptive watermarking algorithm could be built on this formula with image statistics, such as brightness and contrast.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.3
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• pp.192-207
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• 2006

Today, the SSL protocol has been used as core part in various computing environments or security systems. But, the SSL protocol has several problems, because of the rigidity on operating. First, SSL protocol brings considerable burden to the CPU utilization so that performance of the security service in encryption transaction is lowered because it encrypts all data which is transferred between a server and a client. Second, SSL protocol can be vulnerable for cryptanalysis due to the key in fixed algorithm being used. Third, it is difficult to add and use another new cryptography algorithms. Finally. it is difficult for developers to learn use cryptography API(Application Program Interface) for the SSL protocol. Hence, we need to cover these problems, and, at the same time, we need the secure and comfortable method to operate the SSL protocol and to handle the efficient data. In this paper, we propose the SSL component which is designed and implemented using CBD(Component Based Development) concept to satisfy these requirements. The SSL component provides not only data encryption services like the SSL protocol but also convenient APIs for the developer unfamiliar with security. Further, the SSL component can improve the productivity and give reduce development cost. Because the SSL component can be reused. Also, in case of that new algorithms are added or algorithms are changed, it Is compatible and easy to interlock. SSL Component works the SSL protocol service in application layer. First of all, we take out the requirements, and then, we design and implement the SSL Component, confidentiality and integrity component, which support the SSL component, dependently. These all mentioned components are implemented by EJB, it can provide the efficient data handling when data is encrypted/decrypted by choosing the data. Also, it improves the usability by choosing data and mechanism as user intend. In conclusion, as we test and evaluate these component, SSL component is more usable and efficient than existing SSL protocol, because the increase rate of processing time for SSL component is lower that SSL protocol's.

• Journal of Korea Water Resources Association
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• v.48 no.8
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• pp.613-623
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• 2015

To overcome the difficulties of discharge measurements during flood season, MWSCM(micowave water surface current meter) which measures river surface velocities without contacting water has been applied in field work since its development. The existing version of MWSCM is for floods so that its applicability is low due to the short periods of floods. Therefore the renovative redesign of MWSCM to increase the applicability was conducted so that it can be applied to the discharge measurements during normal flows as well as flood ones by extending the measurable range of velocity. A newly developed high-performance MWSCM for general use can measure the velocity range of 0.03-20.0 m/s from flood flows to normal flows, whereas MWSCM for floods can measure the velocity range of 0.5-10.0 m/s. The improvement of antenna isolation between transmitter and receiver to block the inflow of transmitted singals to receiver and the improvement of phase noise of oscillator are necessary for detecting low velocity with MWSCM technology. Separate type antenna of transmitting and receiving signals is developed for isolation enhancement and phase locked loop synthesizer as an oscillator is applied to high-performance MWSCM for general use. Microwave frequency of 24 GHz is applied to the new MWSCM rather than 10 GHz to make the new MWSCM small and light for convenient use of it at fields. Improvement requests on MWSCM for floods-stable velocity measurement, self test, low power consumtion, and waterproof and dampproof-from the users of it has been reflected on the development of the new version of MWSCM.

• Radiation Oncology Journal
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• v.21 no.4
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• pp.291-298
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• 2003

Purpose: We report upon a web-based system for Patterns of Care Study (PCS) devised for Korean radiation oncology. This PCS was designed to establish standard tools for clinical quality assurance, to determine basic parameters for radiation oncology processes, to offer a solid system for cooperative clinical studies and a useful standard database for comparisons with other national databases. Materials and Methods: The system consisted of a main server with two back-ups in other locations. The program uses a Linux operating system and a MySQL database. Cancers with high frequencies in radiotherapy departments in Korea from 1998 to 1999 were chosen to have a developmental priority. Results: The web-based clinical PCS .system for radiotherapy in www.pcs.re.kr was developed in early 2003 for cancers of the breast, rectum, esophagus, larynx and lung, and for brain metastasis. The total number of PCS study items exceeded one thousand. Our PCS system features user-friendliness, double entry checking, data security, encryption, hard disc mirroring, double back-up, and statistical analysis. Alphanumeric data can be input as well as image data. In addition, programs were constructed for IRB submission, random sampling of data, and departmental structure. Conclusion: For the first time in the field of PCS, we have developed a web-based system and associated working programs. With this system, we can gather sample data in a short period and thus save, cost, effort and time. Data audits should be peformed to validate input data. We propose that this system should be considered as a standard method for PCS or similar types of data collection systems.

• Journal of Korean Home Economics Education Association
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• v.32 no.3
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• pp.97-110
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• 2020

The purpose of this study is to develop milk education materials for adults based on the scientific basis of right milk consumption in the format of card news that can be easily accessed on a mobile phone or the internet and has high impact. The topics to be included in the card news were selected based on the findings from literature analysis and focus group interviews with 10 adults(32.0±6.4 years). For the eight selected topics, effective communication was made by suggesting some information that users want to know while reflecting adult eating habits, lifestyle habits, and nutrition and health interests. The card news draft was reviewed by researcher and consulting experts, and then questionnaire survey was conducted using Likert 5-point scales by 50 adults(42.7±10.2 years). Based on the results of the review, consultation and questionnaire survey, a final draft of the card news consisting of 11 cuts was completed. Card news proposal is expected to produce educational effects, since the respondents showed high satisfaction with the card news (higher than 4 on the 5-point scales) according to the questionnaire survey. Adults can easily access and use the card news developed in this study, and thus this card news is expected to increase milk consumption in adulthood and improve nutrition and health through friendly and systematic milk education.

• The Journal of Society for e-Business Studies
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• v.21 no.3
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• pp.51-78
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• 2016

Online-to-offline (O2O) commerce is the new trend that merges online commerce with traditional industries in various fields. The primary purpose of this paper is to find out which factors influence customers' intention to switch from call-based driver-for-hire services to O2O app-based services. This study used variables and factors based on Theory of Switching Intention, and Extended Unified Theory of Acceptance and Use of Technology in order to design research questions. We surveyed 500 users of call-based driver-for-hire services. According to the result of this study, dissatisfaction with the current call-based driver-for-hire services is estimated to be a significant factor that strengthens customers' intention to switch from the call-based driver-for-hire services to the app-based services. Loyalty to the previous call-based driver-for-hire services was not seen as a crucial motivator that causes customers to switch to the new O2O driver service. Switching cost also did not play a key role in explaining the relationship between dissatisfaction with the current call-based service and the intention to use the new app-based service. Performance expectancy, easiness in use, the level of user's knowledge or available assistance in relation to the use of app-based services, and expectancy for reasonable price was found to have meaningful impacts on customers' intention to switch from the call-based driver-for-hire services to the app-based services. Age, gender and user experience on the new service were found incapable of moderating the relationship between aforementioned factors which influence customers' choice of the app-based driver-for-hire service, and customers' intent to switch to the app-based service.

• Progress in Medical Physics
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• v.25 no.4
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• pp.264-270
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• 2014

This study developed a portable respiratory training device to improve breathing stability, which is an important element in using the CyberKnife Synchrony respiratory tracking device, one of the typical Stereotactic Radiation Therapy (SRT) devices. It produced an interface for users to be able to select one of two displays, a graph type and a bar type, supported an auditory system that helps them expect next respiration by improving a sense of rhythm of their respiratory period, and provided comfortable respiratory inducement. By targeting 5 applicants and applying individual respiratory period detected through a self-developed program, it acquired signal data of 'guide respiration' that induces breathing through signal data gained from 'free respiration' and an auditory system, and evaluated the usability by comparing deviation average values of respiratory period and respiratory amplitude. It could be identified that respiratory period decreased $55.74{\pm}0.14%$ compared to free respiration, and respiratory amplitude decreased $28.12{\pm}0.10%$ compared to free respiration, which confirmed the consistency and stability of respiratory. SBRT, developed based on these results, using the portable respiratory training device, for liver cancer or lung cancer, is evaluated to be able to help reduce delayed treatment time due to respiratory instability and improve treatment accuracy, and if it could be applied to developing respiratory training applications targeting an android-based portable device in the future, even use convenience and economic efficiency are expected.

• The Journal of Information Systems
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• v.25 no.1
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• pp.1-23
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• 2016

Purpose Self-congruity deals with the effect of symbolic value-expressive attributes on consumer decision and behavior, which is the theoretical foundation of the "non-utilitarian destination positioning". Functional congruity refers to utilitarian evaluation of a product or service by consumers. In addition, recent years, social network services, especially mobile social network services have created many opportunities for e-WOM communication that enables consumers to share personal consumption related information anywhere at any time. Moreover, self-construal is a hot and popular topic that has been discussed in the field of modem psychology as well as in marketing area. This study aims to examine the moderating effect of self-construal on the relationship between self-congruity, functional congruity and tourists' positive electronic word of mouth (e-WOM). Design/methodology/approach In order to verify the hypotheses, we developed a questionnaire with 32 survey items. We measured all the items on a five-point Likert-type scale. We used Sojump.com to collect questionnaire and gathered 218 responses from whom have visited Korea before. After a pilot test, we analyzed the main survey data by using SPSS 20.0 and AMOS 18.0, and employed structural equation modeling to test the hypotheses. We first estimated the measurement model for its overall fit, reliability and validity through a confirmatory factor analysis and used common method bias test to make sure that whether measures are affected by common-method variance. Then we tested the hypotheses through the structural model and used regression analysis to measure moderating effect of self-construal. Findings The results reveal that the effect of self-congruity on tourists' positive e-WOM is stronger for tourists with an independent self-construal compared with those with interdependent self-construal. Moreover, it shows that the effect of functional congruity on tourists' positive e-WOM becomes salient when tourists' self-construal is primed to be interdependent rather than independent. We expect that the results of this study can provide important implications for academic and practical perspective.