• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.12
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• pp.27-34
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• 2018

This paper considers the seismic performance of lever-type tuned mass damper(TMD). The lever-type TMD is designed utilizing the seismic-performance of TMD and the control force required for constraining story drift. The TMD is basically designed by tuning the frequency of primary structure. Thus, the TMD plays an important role to reduce the dynamic responses. The lever-type TMD has a merit to control more displacement responses than the existing TMD due to the control forces. It is shown that the optimum design of lever-type TMD is affected by the ratio of the TMD mass with respect to the mass of the primary structure, the damping ration of the primary structure, and the length ratio of the lever. A numerical example exhibits the effectiveness of the dynamic control by the lever-type TMD and its validity is illustrated in a three-story building structure subjected to earthquake.

• Journal of Korean society of Dental Hygiene
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• v.22 no.1
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• pp.37-45
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• 2022

Objectives: The purpose of this study is to analyze the relationship between dental caries and the frequency of dental cariesrelated dietary intake among primary, middle, and high school students. It is intended to be used as a basic data for adolescent dietary guidance. Methods: The data were analyzed using the health questionnaire survey and oral examination data from the raw data of the 2019 student health test sample statistics conducted by the Korean Ministry of Education. A total of 59,370 primary, middle, and high school students were selected. Results: For middle and high school students, the more frequent the intake of sodas, the more cases of dental caries were noted. The rate of dental caries was increased in comparison to the group which did not consume dairy products or consumed these once or twice a week. Conclusions: For middle and high school students, dietary guidance should be employed so that consumption of sodas will decrease or consumption will be reduced to less than twice a week.

• Phonetics and Speech Sciences
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• v.8 no.1
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• pp.25-36
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• 2016

Previous studies showed that the voice onset time (VOT) of aspirated and lenis stops has been merged, and post-stop fundamental frequency (F0) has emerged as a primary cue to distinguish the two stops in the younger generation and female speech. The purpose of this study is to demonstrate that VOT merger in aspirated and lenis stops occurs after an F0 difference between the two stops becomes stabilized. In other words, unless post-stop F0, which is a redundant feature, is fully developed, it is hard for VOT merger to happen. Females have got a stable F0 difference in stops earlier than males. Therefore, VOT merger could happen, and as a result, females could take the lead in changing from VOT to F0 in initial stops. This study also shows that speakers who acquired F0 as a primary cue use F0 to the full to distinguish lenis stops from two other stops (aspirated and fortis).

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.777-788
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• 2005

The primary stability of implants is an important factor to predict the osseointegration. Recently, the resonance frequency analysis has been used to measure the primary stability. It is an objective method to monitor the stability of implants during healing phase. This study is to validate the differences in the effect of the osteotome method according to the bone quality as well the thickness of cortical bone. Two hundred seventy implants of 3.75mm in diameter(Neoplant, Neobiotech, Korea) were placed in 135 bovine ribs. The bone quality is classified into 3 classes according to the number of bone marrow spaces which implants would be placed, and then classified into 9 subclasses after the ribs were trimmed. Two implants were placed in 15 specimens of each class. The conclusion were as follows: 1. In case of less dense cancellous bone, the oseotome method is more effective in primary stability rather than the drilling method(p <0.05). 2. If there was cortical bone, it is more advantagous to get stronger primary stability. 3. If cancellous bone is more dense or if cortical bone exists, there is no statistical significance between drilling and osteotome method(p <0.05).

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.486-488
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• 1996

A dc-dc converter which transfers l2-48W of power(regulated output voltage 24V) across a large, variable air gap(1-2cm) has been designed. This converter employs double resonance to compensate the large leakage inductance of the primary and secondary of the transcutaneous transformer. To maximize the effect of resonance, a constant frequency, duty cycle control method is used. The duty cycle control presents advantages over a frequency control in terms of increase in dc voltage gain and reduction of the primary current. The analysis and design procedure for the proposed scheme is presented and the performance result is simulated and verified experimentally.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.233-235
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• 2005

Non-contact power supply (NCPS), as a clean and safe energy supply concept has been applying wildly. Comparing with the conventional transformer the non-contact transformer has a large air gap between the long primary winding and the secondary winding. Due to it, the non-contact transformer has increased leakage inductance and reduced magnetizing inductance. So the high frequency series resonant converter has been widly used on the non-contact power supply system for transferring the primary power to the secondary one, from what a high influence voltage can be gained on the secondry coil even though the large air gap exists. However, it still has the disadvantages of the load sensitive voltage gain characteristics when load is changing. In this paper, we propose a fuzzy logic controller to adjust the frequency of the inverter to track the resonat which is changing when the load is change.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.459-465
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• 2011

A phasor estimation algorithm based on the least square curve fitting technique for the distorted secondary current due to current transformer (CT) saturation is proposed. The mathematical form of the secondary current during CT saturation is represented as the scaled primary current with magnetizing current. The information on the scaled primary current is estimated using the least square technique, with the measured secondary current in the saturated section. The proposed method can estimate the phasor of a fundamental frequency component during the saturated period. The performance of the algorithm is validated under various fault and CT conditions using a C400 CT model. A series of performance evaluations shows that the proposed phasor estimation algorithm can estimate the phasor of the fundamental frequency component with high accuracy, regardless of fault conditions and CT characteristics.

• Journal of the Korean Society of Combustion
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• v.18 no.4
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• pp.21-28
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• 2013

HCCI engines have mainly focused on achieving low temperature combustion in order to obtain higher efficiency and lower emission. One of practical difficulties in HCCI combustion is to control the start of combustion and subsequent combustion phasing. The choice of primary reference fuels in HCCI strategy is one of various promising solutions to make HCCI combustion ignition-controlled. The behavior of ignition delay to the frequency variation of sinusoidal velocity oscillation is computationally investigated under HCCI conditions of PRF75 using a reduced chemistry in a counterflow configuration. The second-stage ignition is more delayed as the higher frequency is imposed on nozzle velocity fluctuation whereas the first-stage ignition is not much influenced.

• The Journal of Pediatrics of Korean Medicine
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• v.18 no.2
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• pp.77-91
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• 2004

Objectives : In evaluating a child with enuresis, an organized approach to the history leads to a working diagnosis and an appropriate treatment plan. but, there's no study about history taking in enuretic children. This article was undertaken to evaluate the enuretic child exactly and to study nocturnal enuresis systematically. Methods : It was conducted a computerized literature search in following database: Medline (via Pubmed), NDSL, EBSCO. Korean articles via oriental pediatric association homepage, KISS. Key words to search were 'nocturnal enuresis', 'bedwetting', 'enuresis', 'incontinence', 'management', 'evaluation', 'assessment', 'questionnaire', 'guideline', 'voiding dysfunction'. Results : Questions are grouped in eight categories: primary history(sex, age, height, weight), family history, enuresis history(primary/secondary, frequency, time of enuresis, nocturia), voiding history(average number, frequency, pattern, volume, posture, daytime enuresis), medical history, constipation/encopresis, sleep(OSA). Conclusion : A careful, complete history taking will help to plan treatment properly and to study.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.65-70
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• 2001

An investigation into asymmetric vibrations of a clamped circular place under a harmonic excitation is made. We examine a primary resonance. in which the frequency of excitation is near the natural frequency of an asymmetric mode of the plate. We found not only a response haying the form of standing wave but also one having the form of traveling wave, which was not observed by Sridhar, Mook and ${Nayfeh}^{(1)}$