• 한국산업융합학회 논문집
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• 제21권5호
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• pp.247-255
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• 2018

In this research, the effect of normal load, sliding velocity, and texture density on thefriction coefficient of surfaces micro-textured on AISI 4140 under paraffin oil lubrication were investigated. The predicted tribological behavior by numerical calculation can be serves as guidance for the designer during the machine development stage. Therefore, in this research friction coefficient prediction model based on response surface methodology (RSM), support vector machine (SVM), and artificial neural network (ANN) were developed. The experimental result shows that the variation of load, speed and texture density were influence the friction coefficient. The RSM, ANN and SVM model was successfully developed based on the experimental data. The ANN model can effectively predict the tribological characteristics of micro-textured AISI 4140 in paraffin oil lubrication condition compare to RSM and SVM.

• Journal of Power Electronics
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• 제19권1호
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• pp.190-200
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• 2019

The flyback converter, which can be regarded as a nonlinear time-varying system, has complex dynamics and nonlinear behaviors. These phenomena can affect the stability of the converter. To simplify the modeling process and retain the information of the output capacitor branch, a special sampled-data model of a peak current-mode (PCM) controlled flyback converter is established in this paper. Based on this, its dynamic behaviors are analyzed, which provides guidance for designing the circuit parameters of the converter. With the critical stability boundary equation derived by a Jacobian matrix, the stable operation range with a varied output capacitor, proportional coefficient of error the amplifier, input voltage, reference voltage and slope of the compensation ramp of a PCM controlled flyback converter are investigated in detail. Research results show that the duty ratio should be less than 0.5 for a PCM controlled flyback converter without ramp compensation to operate in a stable state. The stability regions in the parameter space between the output capacitor and the proportional coefficient of the error amplifier are enlarged by increasing the input voltage or by decreasing the reference voltage. Furthermore, the ramp compensation also can extend to the stable region. Finally, time-domain simulations and experimental results are presented to verify the theoretical analysis results.

• 대한장애인치과학회지
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• 제14권2호
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• pp.71-77
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• 2018

This study was designed to evaluate basic data about dental treatment under general anesthesia in pediatric dentistry of Wonju Severance Christian Hospital. Sex, Age, location, preoperative physical status, intubation methods, inhalation agents, duration of anesthesia and treatment, performed treatment and postoperative follow-up period and frequency were collected based on electronic medical records of 239 patients who visited pediatric dentistry at Wonju Severance Christian Hospital from March 2011 to February 2017. There were the most patients between the ages of 5 - 9, and there was no significant difference between male and female. The largest number of patients visited the hospital from Wonju, where the hospital was located. Most of preoperative status was ASA Class I. Orotracheal intubation was used in 169 of patients (70.7%). As an anesthesia maintenance agent, drug containing sevoflurane was used in 153 of patients (64.0%). In performed treatment, dental restoration, sealant and stainless steel crowns were performed 3.8, 1.8 and 1.1 times per person. 129 patients (54.0%) attended follow-up appointments under 6 months and those of the number of appointments were 1 - 4 times in average. General anesthesia as a behavior guidance in pediatric dentistry is increasing. Clinical guidelines for pediatric patients under general anesthesia are required through follow-up studies.

• 디지털융복합연구
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• 제19권2호
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• pp.531-538
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• 2021

이 연구는 무용전공 고등학생의 자기관리가 섭식태도와 섭식장애에 미치는 영향을 규명하는데 목적이 있다. 연구대상은 서울과 경기도, 충청도에 소재하고 있는 예술고등학교 무용전공 고등학생 239명으로, 조사도구는 설문지를 사용하였다. 자료 분석은 다중회귀분석과 위계적 회귀분석을 실시하여 다음과 같은 결과를 도출하였다. 첫째, 무용전공 고등학생의 대인관리는 절제된 섭식에 영향을 미치며, 몸 관리는 외부적 섭식과 정서적 섭식에 영향을 미친다. 둘째, 무용전공 고등학생의 자기관리는 거식증에 유의한 영향을 미친다. 셋째, 무용전공 고등학생의 섭식태도는 자기관리와 섭식장애를 강력하게 매개한다. 이상의 결과는 무용전공 고등학생들의 지나친 신체에 대한 관리는 섭식태도와 거식증에 높은 영향을 미친다는 것을 의미한다. 이에 따라 학생들의 올바른 섭식행동을 위한 지도자들의 세심한 지도가 필요한 것으로 사료된다.

• 대한지역사회영양학회지
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• 제25권6호
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• pp.451-463
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• 2020

Objectives: The purpose of this study was to develop and evaluate booklets and video clips to prevent children from picky eating. Methods: Based on a survey conducted on food preferences of preschool children aged 2 to 5 years, 14 kinds of less preferred vegetables were selected. Accordingly, educational videos, activity books, and teaching-learning guides were produced for preschool children using the 'food bridge' theory, and the educational materials were named "Friendly vegetables". Educational materials were distributed to childcare institutions, and their effectiveness was investigated for preschool children who were instructed on these materials once every 30 days from March to November, 2019. The children were examined for changes in their knowledge of names, colors, taste/texture, methods of cultivation, and preferences for vegetables before and after the instructional course. Results: The awareness of vegetables increased significantly in younger children and the picky eating group. When the assessment was carried out in terms of vegetable knowledge, it was observed that the younger the age or the pickier the in eating food, the more effective the education is compared to the counter part. The preference for vegetables also increased after the instruction compared to the pre-instruction period, but significant changes were seen only in the 2~3 year age group for boys and girls. Also, only the picky group of girls showed changes in preference. The children's average interest in the education materials was 3.85 points out of 5 points. Conclusions: Through this study, we have developed educational materials for standalone use in childcare facilities and confirmed that they have a significant effect on improving awareness and preferences related to vegetables. In summary, the younger the age or the pickier the child in eating food, the more effective the education. It is believed that additional education on mealtime guidance is needed which can alter the eating behavior of preschool children and improve their diet. It is proposed to widen the scope of use of the materials by collecting diverse opinions from child care teachers.

• 문화기술의 융합
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• 제7권1호
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• pp.424-431
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• 2021

본 연구는 저출산·고령화, 만혼, 비혼, 별거, 사별, 귀농귀촌 등으로 인한 가족구조의 변화, 노동시장의 유연성 증대 등으로 인한 1인가구 증가라는 현상에 대해 1인가구의 화재예방 대책을 탐구하고 있다. 1인가구의 화재에 영향을 미치는 요인은 구조적 차원에서 주거환경문제가 있다. 행태적 측면에서 반려동물 양육에 따른 화재발생 증가가 있다. 1인가구의 화재예방을 위해서는 구조적 차원에서 주거환경 개선을 위한 예외 없는 안전규제가 필요하다. 행태적 차원에서는 관계기관 예방안전지도의 확대 적용이 필요하다. 또한 반려동물로 인한 화재 예방을 위한 조치로서 전기레인지의 제조사들은 반려동물로 인한 화재를 예방하는 안전장치, 예를 들면 자동 전원 차단장치나 타이머를 활용한 전원 공급 등을 개발해야 한다. 반려동물을 안전하게 키우기 위해 필요한 조치들을 홍보영상으로 만들어 배포하거나 가상현실로 구현된 재난대비 프로그램을 개발해서 보급하는 것도 중요한 수단이 될 수 있다.

• Geomechanics and Engineering
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• 제30권1호
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• pp.93-105
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• 2022

With the exploitation of natural resources in China, underground resource extraction and underground space development, as well as other engineering activities are increasing, resulting in the creation of many defective rocks. In this paper, uniaxial compression tests were performed on rocks with double holes and fractures at different angles using particle flow code (PFC2D) numerical simulations and laboratory experiments. The failure behavior and mechanical properties of rock samples with holes and fractures at different angles were analyzed. The failure modes of rock with defects at different angles were identified. The fracture propagation and stress evolution characteristics of rock with fractures at different angles were determined. The results reveal that compared to intact rocks, the peak stress, elastic modulus, peak strain, initiation stress, and damage stress of fractured rocks with different fracture angles around holes are lower. As the fracture angle increases, the gap in mechanical properties between the defective rock and the intact rock gradually decreased. In the force chain diagram, the compressive stress concentration range of the combined defect of cracks and holes starts to decrease, and the model is gradually destroyed as the tensile stress range gradually increases. When the peak stress is reached, the acoustic emission energy is highest and the rock undergoes brittle damage. Through a comparative study using laboratory tests, the results of laboratory real rocks and numerical simulation experiments were verified and the macroscopic failure characteristics of the real and simulated rocks were determined to be similar. This study can help us correctly understand the mechanical properties of rocks with defects and provide theoretical guidance for practical rock engineering.

• Journal of Dental Anesthesia and Pain Medicine
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• 제21권4호
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• pp.345-355
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• 2021

Background: This study aimed to evaluate the efficacy of external vibrating devices and counterstimulation on a child's dental anxiety, apprehension, and pain perception during local anesthetic administration. Methods: This was a prospective, randomized, parallel-arm, single-blinded interventional, clinical trial. One hundred children aged 4-11 years, requiring pulp therapy or extraction under local anesthesia (LA), were recruited and allocated equally into two groups (1:1) based on the interventions used: Group BD (n = 50) received vibration using a Buzzy^® device {MMJ Labs, Atlanta, GE, USA} as a behavior guidance technique; Group CS (n = 50) received counterstimulation for the same technique. Anxiety levels [Venham's Clinical Anxiety Rating Scale (VCARS), Venham Picture Test (VPT), Pulse oximeter {Gibson, Fingertip Pulse Oximeter}, Beijing, China)] were assessed before, during, and after LA administration, while pain perception [Wong-Baker Faces Pain Rating Scale (WBFPS), Visual Analogue Scale (VAS)] was evaluated immediately after injection. Statistical analysis was performed using the Student's t-test to assess the mean difference between the two groups and the repeated measures ANOVA for testing the mean difference in the pulse rates. Statistical significance was set at P < 0.05. Results: Significant differences in mean pulse rate values were observed in both groups. In contrast, the children in the BD group had higher diminution (P < 0.05), whereas the mean VCARS and VPT scores were conspicuous (P < 0.05). Based on the mean WBFPS and VAS scores, delayed pain perception after LA injection was more prominent in the BD group than in the CS group. Conclusion: External vibration using a Buzzy^® device is comparatively better than counterstimulation in alleviating needle-associated anxiety in children requiring extraction and pulpectomy.

• 디지털융복합연구
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• 제19권11호
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• pp.397-406
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• 2021

국내 의료기사 등에 관한 법률에서 의료기사는 의사 또는 치과의사의 지도 아래 업무를 행하는 것으로 되어있다. 하지만 실제 업무행태 및 국내외적 경향, 그리고 의료기사의 교육 수준을 고려한다면 전문성을 인정해주어야 한다. 이러한 전문적이고 독립적인 운영시스템은 의료기사의 자율성을 보장해주어야 하며, 법률적으로도 변화가 필요하다고 할 수 있다. 즉, 우수한 교육과정과 많은 나라에서 "요청", "협조" 등의 개념을 적용하는 시대적 요구에 따라 "지도" 보다는 "의뢰 및 처방"으로 변경이 필요하다. 이러한 변화는 시대적 요구라 할 수 있고 의료서비스의 향상, 그리고 사회적 기여를 위한 변화라고 할 수 있다.

• 한국해양공학회지
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• 제36권3호
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• pp.181-193
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• 2022

This study presents a mission management technique that is a key component of underwater docking system used to expand the operating range of autonomous underwater vehicle (AUV). We analyzed the docking scenario and AUV operating environment, defining the feasible initial area (FIA) level, event level, and global path (GP) command to improve the rate of docking success and AUV safety. Non-holonomic constraints, mounted sensor characteristic, AUV and mission state, and AUV behavior were considered. Using AUV and docking station, we conducted experiments on land and at sea. The first test was conducted on land to prevent loss and damage of the AUV and verify stability and interconnection with other algorithms; it performed well in normal and abnormal situations. Subsequently, we attempted to dock under the sea and verified its performance; it also worked well in a sea environment. In this study, we presented the mission management technique and showed its performance. We demonstrated AUV docking with this algorithm and verified that the rate of docking success was higher compared to those obtained in other studies.