• Science of Emotion and Sensibility
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• v.22 no.3
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• pp.3-20
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• 2019

With advancements in technology of virtual reality, it is used for various purposes in many fields such as medical care and healthcare, but as the same time there are also increasing reports of nausea, eye fatigue, dizziness, and headache from users. These symptoms of motion sickness are referred to as cybersickness, and various researches are under way to solve the cybersickness problem because it can cause inconvenience to the user and cause adverse effects such as discomfort or stress. However, there is no official standard for the causes and solutions of cybersickness at present. This is also related to the absence of tools to quantitatively measure the cybersickness. In order to overcome these limitations, this study proposed quantitative and objective cybersickness evaluation method. We measured 128-channel EEG waves from ten participants experiencing visually stimulated virtual reality. We calculated the relative power of delta and alpha in 11 regions (left, middle, right frontal, parietal, occipital and left, right temporal lobe). Multiple regression models were obtained in a stepwise manner with the motion sickness susceptibility questionnaire (MSSQ) scores indicating the susceptibility of the subject to the motion sickness. A multiple regression model with the highest under the area ROC curve (AUC) was derived. In the multiple regression model derived from this study, it was possible to distinguish cybersickness by accuracy of 95.1% with 11 explanatory variables (P_D.MF, P_D.LP, P_D.MP, P_D.RP, P_D.MO, P_A.LF, P_A.MF, P_A.RF, P_A.LP, P_A.RP, P_A.MO). In summary, in this study, objective response to cybersickness was confirmed through 128 channels of EEG. The analysis results showed that there was a clearly distinguished reaction at a specific part of the brain. Using the results and analytical methods of this study, it is expected that it will be useful for the future studies related to the cybersickness.

• 대한공업교육학회지
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• v.39 no.2
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• pp.81-100
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• 2014

This study developed training program to educate professional workers for software industry with growing importance in this area as software industry takes more parts in Korean economy. Additionally, this study developed the program based on national competency standards(NCS) using structured on the job training(S-OJT), For this study, we reviewed economic index about software industry such as economic ratio and the influx of the workforce. Also literature review for S-OJT was conducted to explore its concept for better application of the concept to the program development. In addition, this study used training program development manual suggested by Korean Department of Labor. We selected specific job which needs training program to be developed based on thorough needs analysis for a company A. Previously developed NCS and other documents were reviewed and focus group interviews were conducted to find out core knowledge and skills for the job. 44 training programs were developed and objective of each program, hours, contents and methods were also suggested. Additionally detailed program name, education system, road map and operation strategy were developed and suggested. The result of this study is expected to contribute to other industry and jobs which are facing to the development of NCS based education program by suggesting detailed stage of development process. For more animated development of education program using NCS, the effect of the program should be tested in the future. For the test, appropriate evaluation methods and measures should be developed as well.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.558-565
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• 2016

Recent 3D printing technology has been grafting onto various medical practices. In light of this trend, this research is intended to examine the figuration surface's accuracy of 3D images made by using DICOM images after printing by 3D printing. The medical images were obtained from animal bone objects, while the objects were printed after undergoing STL file conversion for 3D printing purposes. Ultimately, after the 3D figuration, which was obtained by the original animal bones and 3D printing, was scanned by 3D scanner, 3D modeling was merged each other and the differences were compared. The result analysis was conducted by visual figuration comparison, color comparison of modeling's scale value, and numerical figuration comparison. The shape surface was not visually distinguished; the numerical figuration comparison was made from the values measured from the four different points on the X, Y and Z coordinates. The shape surface of the merged modeling was smaller than the original object (the animal bone) by average of -0.49 mm in the 3D printed figuration. However, not all of the shape surface was uniformly reduced in size and the differences was within range of -0.83 mm on the experiment.

• Journal of Sericultural and Entomological Science
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• v.47 no.2
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• pp.93-98
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• 2005

The antioxidant capacity of yield-type mulberry leaves and fruits (Morus alba L., M. bombycis Koidz, and M. Lhou (Ser). Koidz) collected from In-je, Won-ju and Yang-yang regions, Kang-won province, Korea, was investigated with minium L-100 device and ARAW-KIT (anti-radical ability of water-soluble substance), in comparison to the ascorbic acid. The results indicated that total antioxidant capacity of yield-type mulberry leaves was 2711.2 nmol (ascorbic acid equivalents). The highest stage of antioxidant capacity (3587.6 nmol) was opening stage of five leaves in spring. Especially, antioxidant capacity of mulberry leave collected from In-je region was high than that of other regions. No. 7 mulberry leave showed the strongest antioxidant capacity (6184.9 nmol) at opening stage of five leaves in spring. Also, fluit growing condition including fruit size and yield was good, too. Therefore, No. 7 mulberry three from In-je region, possessed not only high antioxidant capacity but also considerable fruit quality, was selected as potent resource for mulberry breeding and functional material development.

• Korean Journal of Social Welfare
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• v.63 no.2
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• pp.207-231
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• 2011

This study aims to identify constructs of cultural competency specifically relevant to the Korean society and to test its reliability and validity among human service workers. For the purpose of the study, authors conducted focus group interviews and conferences with human service workers to draw the concept of cultural competency. Further, this study conducted to two separate pilot tests with 20 social workers with practice experiences in order to clarify descriptions and relevance of scale items. Based on the literature review on the concept of cultural competency and analysis of focus group interviews, 40 items were initially constructed and then were reduced to a 32-item scale after two separate pilot studies. Meantime, suggestions made by an advisory group were also reflected in the scale development process. Finally, one hundred ninety four workers in social service agencies were recruited to evaluate the relevance of the scale items in a 5 point Likert scale. Through exploratory and confirmatory factor analysis, 4 main factors were identified: 1) competency to use culturally relevant skills, 2) cultural awareness and sensitivity, 3) cultural knowledge, and 4) efforts to overcome cultural differences. These factors were consistent with sub-concepts of cultural competency in other studies. Confirmatory factor analysis also showed that the model fitness was at the high level and convergent analysis with the similar scale also showed high correlations. Internal consistency also remained at a high level. Based on the results, implication for social work practice and education were discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.461-467
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• 2003

This paper proposes the method of mobility implementation for location searching in the intelligence wireless ATM networks that expand and apply standard broadband signaling capabilities, and analyze the performance based on the numerical algorithm. The existing B-ISDN UNI protocol stack demands the location search mechanism to determine the location of mobile terminal in the wireless ATM networks because it use single protocol through the fixed PTP interface or PTM interface that don't support terminal mobility. The proposed method make possible the dynamic mobility at a part of wireless access by minimizing the signaling load without a falling-off in system performance by using the intelligence network technology according to the expansion of ATM and B-ISDN signaling integration based on the fixed networks. We implemented the performance analysis by MFC modeling based on numerical algorithm, and realized the efficiency of expenses by carrying out the comparative signaling performance evaluation to measure the relative gains of location search service in the intelligence wireless ATM system. The obtained results have the flexibility to operate in the public B-ISDN network environment without a change of existing B-ISDN/ATM NNI signaling reference to support the wireless ATM access system, and can easily expand to correspond to terminal mobility and various multimedia services in the next broadband PCS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3235-3245
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• 1996

A DDFS(Direct Digital Frequency Synthesizer) used in spread spectrum communication systems must need fast switching speed, high resolution(the step size of the synthesizer), small size and low power. The chip has been designed with four parallel sine look-up table to achieve four times throughput of a single DDFS. To achieve a high processing speed DDFS chip, a 24-bit pipelined CMOS technique has been applied to the phase accumulator design. To reduce the size of the ROM, each sine ROM of the DDFS is stored 0-.pi./2 sine wave data by taking advantage of the fact that only one quadrant of the sine needs to be stored, since the sine the sine has symmetric property. And the 8 bit of phase accumulator's output are used as ROM addresses, and the 2 MSBs control the quadrants to synthesis the sine wave. To compensate the spectrum purity ty phase truncation, the DDFS use a noise shaper that structure like a phase accumlator. The system input clock is divided clock, 1/2*clock, and 1/4*clock. and the system use a low frequency(1/4*clock) except MUX block, so reduce the power consumption. A 107MHz DDFS(Direct Digital Frequency Synthesizer) implemented using 0.8.mu.m CMOS gate array technologies is presented. The synthesizer covers a bandwidth from DC to 26.5MHz in steps of 1.48Hz with a switching speed of 0.5.mu.s and a turing latency of 55 clock cycles. The DDFS synthesizes 10 bit sine waveforms with a spectral purity of -65dBc. Power consumption is 276.5mW at 40MHz and 5V.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.80-88
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• 2008

In this paper, the block cipher algorithms, 3-DES(Triple Data Encryption Standard), AES(Advanced Encryption Standard), SEED, HASH(SHA-1), which are domestic and international standards, have been implemented as an integrated cryptographic engine for smart card applications. For small area and low power design which are essential requirements for portable devices, arithmetic resources are shared for iteration steps in each algorithm, and a two-level clock gating technique was used to reduce the dynamic power consumption. The integrated cryptographic engine was verified with ALTERA Excalbur EPXA10F1020C device, requiring 7,729 LEs(Logic Elements) and 512 Bytes ROM, and its maximum clock speed was 24.83 MHz. When designed by using Samsung 0.18 um STD130 standard cell library, the engine consisted of 44,452 gates and had up to 50 MHz operation clock speed. It was estimated to consume 2.96 mW, 3.03 mW, 2.63 mW, 7.06 mW power at 3-DES, AES, SEED, SHA-1 modes respectively when operating at 25 MHz clock. We found that it has better area-power optimized structure than other existing designs for smart cards and various embedded security systems.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.2
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• pp.21-27
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• 2008

This paper describes a CMOS 16:1 binary-tree multiplexer(MUX) using $0.18-{\mu}m$ technology. To provide immunity for wide frequency range and process-and-temperature variations, the MUX adopts several delay compensation techniques. Simulation results show that the proposed MUX maintains the setup margins and hold margins close to the optimal value, i.e., 0.5UI, in wide frequency-range and in wide process-and-temperature variations, with standard deviation of 0.05UI approximately. These results represent that these proposed delay compensations are effective and the reliability is much improved although CMOS logic circuits are sensitive to those variations. The MUX is fabricated using $0.18-{\mu}m$ CMOS process, and tested with a test board. At power supply voltage of 1.8-V, maximum data-rate and area of the MUX is 1.65-Gb/s and 0.858 $mm^2$, respectively. The MUX dissipates a power of 24.12 mW, and output eye opening is 272.53 mV, 266.55 ps at 1.65-Gb/s operation.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.1
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• pp.22-30
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• 2008

Purpose: The purpose of this study is to compare three different CAD/CAM systems through the fracture strength of zirconia core and to evaluate the clinical availability of each system. Material and methods: The following three groups of 30 maxillary mesial incisor core for all-ceramics(each group 10) were fabricated as follows: group 1. $Adens^{(R)}$ CAD/CAM system, group 2. $Cerasys^{(R)}$ CAD/CAM system, group 3. 3M $Lava^{(R)}$ CAD/CAM system. All specimens were manufactured consistently thickness 0.5mm and relief $40{\mu}m$. Specimens were subjected to compressive loading on the lingual area by Z250/$SN5S^{(R)}$. Each group's mean and standard deviation were calculated and Kruskal Waillis test, Wilcoxon Rank Sum test were utilized to find out the relationship among the groups. Results: The results were as follows: 1. The mean fracture strength of $Adens^{(R)}$ system was $615.89{\pm}156.1N$, the $Cerasys^{(R)}$ system was $863.98{\pm}151.5N$, and the 3M $Lava^{(R)}$ system was $1143.1{\pm}286.6N$. 2. The fracture strength of the systems showed the significant statistical differences in order of 3M $Lava^{(R)}$ system, $Cerasys^{(R)}$ system, $Adens^{(R)}$ system. Conclusion: In this study, in spite of the differences among the groups, every group showed clinically useful results. It is necessary to study further clinical experiments on a long term basis.