• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.549-556
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• 2016

CVR is a technique for reducing power consumption by reducing the voltage of the system and many demonstrations and studies have been conducted in the past. Recently, SCADA-based or AMI-based VVC have been developed and the CVR is used as an important operation mode. Using a variety of instruments, CVR determines the optimal VVC control references by closed loop control. In this paper, we implemented RTDS-MATLAB integrated simulation environment for development and verification of CVR control algorithm based on voltage measurement. The voltage control device of distribution system was modeled using RTDS and MATLAB has constructed a controller that can measure and control the voltage of the simulation system of RTDS. After the capacitor, which is a reactive power control device, flattens the voltage of the system, the control algorithm reduces the voltage of the system by tap control of the OLTC based on the flatten voltage. The proposed system was verified by simulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1039-1046
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• 2017

Campus microgrid is designed and built by considering not only power generation but also power consumption management as connected microgrid type because the main goal of the campus microgrid is to save power consumption costs. There are many functions to achieve the goal and they are mainly to use generation-based functions such as islanding operation for peak management and for emergency events. In power distribution operation, Conservation Voltage Reduction (CVR) is applied in order to reduce power consumption. The CVR is defined as a function for load consumption reduction by voltage reduction in order to reduce peak demands and energy consumption. However, application of CVR to microgrid is difficult because the microgrid cannot control a tap of transformer in a substation and the microgrid normally is not designed with phase modifying equipment like a step-voltage-regulator which can control voltage in power distribution system operation. In addition, an impact of the CVR is depended on load characteristics such as a normal load, a rated power, and synchronous motors. Therefore, this paper proposes an application of CVR using linear voltage control based AVR in campus microgrid with power consumption reduction considering characteristics of load and component in the microgrid. The proposed system can be applied to each buildings by a configuration of power distribution cables; and the application results and CVR factor are presented in this paper.

• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.247-261
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• 1999

Purpose: The aim of this study was to evaluate the normal values of regional cerebral blood flow (rCBF) and cerebrovascular reserve (CVR) in normal children to aged volunteers using Tc-99m HMPAO, Materials and Methods: Thirty four right-handed normal volunteers (20 males, 14 females, mean age $40.3{\pm}24.9$ years, range 4 to 82 years) were underwent rost/acetazolamide (ACZ) brain SPECT using Tc-99m HMPAO and the sequential injection and subtraction method. rCBF was estimated on the basis of a semiquantitative approach by means of right/left ratio, region/cerebellum and region to whole brain ratios in (rental, parietal, temporal, and occipital lobes, basal ganglia, thalami, and cerebellum. CVR was measured by means of % perfusion increase calculated as % mean count change compared to rest rCBF in each regions. Results: Mean values of right to left ratios range from 1.004 to 1.018, rCBF was highest in cerebellum and lowest in basal ganglia and thalami. Frontal and temporal rCBF decreased while occipital and thalamic rCBF increased according to age. No sexual difference of rCBF was noted. Mean CVR was $29.9{\pm}12.9%$. Mean CVR significantly increased to late teens, and declined thereafter. After 6th decade, CVR in both frontal lobes, left parietal lobe and right basal ganglia decreased significantly with advancing age. There was no sexual difference of CVR. Conclusion: Quantitative assessment of CVR was possible by ACZ Tc-99m HMPAO brain SPECT. It revealed that rCBF and CVR changed according to age in normal Korean volunteers. There was no sexual difference.

• Phonetics and Speech Sciences
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• v.6 no.3
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• pp.165-169
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• 2014

Intelligibility of speech transmitted to listeners can significantly be degraded in noisy environments such as in auditorium and in train station due to ambient noises. Noise-masked speech signal is hard to be recognized by listeners. Among the conventional methods to improve speech intelligibility, consonant-vowel intensity ratio (CVR) approach reinforces the powers of overall consonants. However, excessively reinforced consonant is not helpful in recognition. Furthermore, only some of consonants are improved by the CVR approach. In this paper, we propose the corrective weighting (CW) approach that reinforces the powers of consonants according to syllable-type such as consonant-vowel-consonant (CVC), consonant-vowel (CV) and vowel-consonant (VC) in Korean differently, considering the level of listeners' recognition. The proposed CW approach was evaluated by the subjective test, Comparison Category Rating (CCR) test of ITU-T P.800, showed better performance, that is, 0.18 and 0.24 higher than the unprocessed CVR approach, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.203-203
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• 2012

국제핵융합실험로(ITER)는 2020년경에 제작 설치가 완료될 예정이다. 이 장치에 한국도 시험블랑켓 모듈(Test Blanket Module: TBM)을 장착할 예정이다. 한국은 ITER 참여국 중 유일하게 지름 1 mm의 흑연 페블에 SiC를 코팅한 중성자 반사 재료를 채택한 것이 특징이다. 중성자 반사재료를 이용하게 되면 독성이 강한 중성자 증배재인 Be의 양을 줄일 수 있다. SiC 코팅은 여러 가지 방법이 알려져 있지만, 지름 1 mm 내외의 흑연 페블에 SiC를 골고루 코팅하기 위해서는 여러 가지 기술이 가미되어야 한다. 본 연구에서는 CVD 및 CVR법을 이용해 SiC를 코팅했으며, CVD의 경우 전구체 물질로 $CH_3SiCl_3$가 사용되었으며, 캐리어 가스로는 $H_2$를 사용했다. 그리고 CVR에서는 평균입도 10 ${\mu}m$의 $SiO_2$를 사용했으며, $1,750^{\circ}C$에서 2시간 노출시켰다. 이렇게 얻어진 SiC 코팅은 XRD, EDS, FE-SEM 등을 활용한 여러 가지 분석으로 확인할 수 있었다.

• Journal of Korean society of Dental Hygiene
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• v.21 no.3
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• pp.211-225
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• 2021

Objectives: To validate the role of a new information and communication technology platform that we created for the betterment of the oral health of persons with disabilities and for providing appropriate health care services. Methods: A Delphi survey was conducted among 16 people in various professions, including academia, government agencies, and dentistry, to evaluate the validity of the information and communication technology platform. Moreover, platform satisfaction was evaluated using a user experience questionnaire among 200 people, including persons with disabilities, parents, and public institutions. Results: Experts in consensus indicated a high validity for the categories of service provider (CV=0.29, CVR=0.69), service target (CV=0.29, CVR=0.38), service contests (CV=0.27, CVR=0.63), and financial support (CV=0.30, CVR=0.63) in our information and communication technology platform. In addition, information from questionnaires on user experience and communication technology satisfaction analysis showed that both users and providers were highly satisfied with the platform. Conclusions: The provision of oral health services based on the new information and communication technology platform has numerous advantages, in addition to providing adequate oral health care for the disabled. Furthermore, the social safety net for improved oral health may be further strengthened.

• Journal of Korean society of Dental Hygiene
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• v.22 no.6
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• pp.531-539
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• 2022

Objectives: This study aimed to design a CRA questionnaire specifically for Korean children and adolescents based on the results of two Delphi survey completed by dental professionals. Methods: Based on the CAMBRA^® CRA tool, updated in 2019, we constructed a questionnaire on the oral environment and behavior of children and adolescents. Then, the CVR and I-CVI were evaluated using the results of the first and second Delphi surveys involving 20 professionals. Results: After the first Delphi survey, six items were considered invalid because their CVR and I-CVI were below the recommended values of 0.42 and 0.78, respectively. After receiving feedback from the professional panels, nine items were removed. In the second Delphi survey, the questionnaire contained a total of 21 items, all of which showed good CVR and I-CVI. After modifications based on the opinions of professional panels, the questionnaire was finalized to have 21 questions. Conclusions: The finalized questionnaire with 21 items, based on the opinions of professional panels, showed excellent CVR and I-CVI for all the items. Structured programs with updated guidelines must be developed for Korean children and adolescents in further studies.

• Carbon letters
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• v.8 no.2
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• pp.91-94
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• 2007

The application of Carbon and graphite based materials in unprotected environment is limited to a temperature of $450^{\circ}C$ or so because of their susceptibility to oxidation at this temperature and higher. To over come these obstacles a low cost chemical vapour reaction process (CVR) was developed to give crystalline and high purity SiC coating on graphite and isotropic C/C composite. CVR is most effective carbothermal reduction method for conversation of a few micron of carbon layer to SiC. In the CVR method, a sic conversation layer is formed by reaction between carbon and gaseous reagent silicon monoxide at high temperature. Characterization of SiC coating was carried out using SEM. The other properties studied were hardness density and conversion efficiency.

• Vending industry
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• v.2 no.7 s.8
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• pp.68-72
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• 2003

• Journal of dental hygiene science
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• v.22 no.2
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• pp.115-125
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• 2022

Background: In the dental hygiene curriculum, efforts are being made to introduce an integrated curriculum based on the competency of a dental hygienist. Because there is a connection and overlap in learning contents between Dental Nutrition and Oral Biochemistry, which are basic dental hygiene subjects, it is possible to integrate these two subjects. This study aims to derive Nutritional Biochemistry as an integrated curriculum for Dental Nutrition and Oral Biochemistry, and to develop learning goals and competencies for Dental Nutritional Biochemistry. Methods: The learning contents of the integrated curriculum were composed by referring to the contents of the Dental Nutrition and Oral Biochemistry textbooks, and learning goals were derived from the learning contents. Moreover, competency was developed by analyzing the duties of a dental hygienist that can be performed through the learning goals. The Delphi survey was conducted twice to verify the content validity ratio (CVR) of the competence and the learning goal of the integrated curriculum. Results: In the first Delphi survey, the CVR for two competencies was 0.56 or higher. Moreover, it was revised based on expert's opinions, and as a result of the second Delphi survey after the revision, the CVR was either increased or maintained. Eighty-five learning goals were derived by referring to the textbook. According to CVR and expert opinions, after the first Delphi survey, the number of learning goals was reduced to 69. After the second Delphi survey, 68 learning goals were finally derived. Conclusion: The development process of the integrated curriculum conducted in this study can be utilized for integration between subjects in basic dental hygiene.