• 센서학회지
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• 제30권3호
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• pp.181-184
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• 2021

Interest in healthcare and wearable devices has been increasing recently. A strain sensor is required in various wearable devices. With respect to such devices, studies on resistance changes in strain sensors using flexible materials are in progress. However, the resistance of the rest area in a strain sensor should not change according to the applied strain. So, an electrode with resistance to stretching, bending, and torsion is required in such strain sensors. Tension, bending, and torsion can be realized through structural shape control, rather than by using flexible materials. Further, such an electrode that maintains electrical properties has been developed and manufactured. This electrode can be used in various applications such as foldable devices, e-papers, batteries, and multifunctional wearable devices.

• 한국분말재료학회지
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• 제29권6호
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• pp.505-510
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• 2022

The thermal shock resistance of cement composites with hollow glass microspheres (HGM) is investigated. Cement composites containing various concentrations of HGM are prepared and their properties studied. The density, thermal conductivity, and coefficient of thermal expansion of the composites decrease with increasing HGM concentration. A thermal shock test is performed by cycling between -60 and 50℃. After the thermal shock test, the compressive strength of the cement composite without HGM decreases by 28.4%, whereas the compressive strength of the cement composite with 30 wt% HGM decreases by 5.7%. This confirms that the thermal shock resistance of cement is improved by the incorporation of HGM. This effect is attributed to the reduction of the thermal conductivity and coefficient of thermal expansion of the cement composite because of the incorporation of HGM, thereby reducing the occurrence of defects due to external temperature changes.

• 한국안전학회지
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• 제38권2호
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• pp.15-22
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• 2023

In this study, the process and the environment of a melting furnace, located in Workplace A in Chungnam Province was inspected, and the insulation resistances of electrical circuits and motors were measured, and their changes over five years (2017-2021) were analyzed. It was found that the exhaust fan, oil pumps #A and #B, and heater were installed in 2010. Their insulation resistances decreased from 2017. Specifically, the insulation resistance of Oil Pump #A decreased from 100 (㏁) in 2018 to 20(㏁) in 2021, an 80% reduction. The fast decrease in insulation resistance was due to the high temperature of the melting furnace affecting surrounding the electrical facilities. A safety management scheme on the electrical facility of the melting furnace was proposed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.165-166
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• 2020

The climate on the Korean Peninsula has been warmed recently, abnormal weather conditions such as heat waves, cold waves, and tropical nights have been detected frequently. Precisely, the number of days with cold waves in the winter has increased, and rapid changes of temperature in the morning and afternoon have occurred frequently in the 2000s. Due to the previous phenomenons, this research is focused on evaluating the concrete's Chloride Penetration Resistance and Durability, and the difference of the resistance according to the W/C.

• International Journal of Internet, Broadcasting and Communication
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• 제16권1호
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• pp.148-155
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• 2024

We are designed was to find an efficient warm-up method for resistance training for muscle hypertrophy, and 10 males with at least 3 years of resistance training experience were selected as subjects. The 75% 1RM was measured directly based on the pre-measured bench press 1RM. After that, the main experiment of 75% 1RM bench press according to the three warm-up methods was conducted one week apart, and all experiments were randomized and cross-over. Performance according to the warm-up method (3) was measured by total exercise volume, and physiological changes were determined by myocardial workload. All post-measurement data were analyzed using SPSS.22.0 and analyzed using repeated measures one-way ANOVA and contrast comparisons were made using the deviation method. The results showed that the method of gradually increasing the number of repetitions by performing the same intensity as the intensity of the main exercise in the form of muscle hypertrophy, but at submaximal repetitions, showed the highest performance.

• Journal of Oral Medicine and Pain
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• 제20권1호
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• pp.117-126
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• 1995

In order to evaluate objectively the level of tension and relaxation in dental practices, the author used Biotrainer(BF-102R), one of the GSR biofeedback apparatus, to examine 119 dental outpatients on their changes of GSR due to infection, preparation, extraction and readjustment. The obtained results were as follows : 1. There were no differences in the baseline GSR between the control group and the patient groups. 2. Changes in GSR by practices were significantly larger than the baseline GSR. 3. GSR in female was larger than that in male 4. While the GSR after injection, preparation and extraction revealed lower level, the GSR after readjustment revealed higher level. 5. Most of subjects just after injection, preparation and extraction were more frequent in decrease of GSR and those just after readjustment more were frequent n increase of GSR. 6. Type 1,2(increase in skin resistance) showed greater in injection, preparation and extraction group, while type 3(decrease in skin resistance) did in readjustment group.

• 센서학회지
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• 제20권3호
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• pp.168-171
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• 2011

Porous 3C-SiC(pSiC) samples with different pore diameters were prepared from poly crystalline N-type 3C-SiC by electrochemical anodization. The pSiC surface was chemically modified by the sputtering of Pd and Pt nano-particles as a hydrogen catalyst. Changes in resistance were monitored with hydrogen concentrations in the range of 110 ppm - 410 ppm. The variations of the electrical resistance in the presence of hydrogen demonstrated that Pd and Pt-deposited pSiC samples have the ability to detect hydrogen at room temperature. Regardless of the catalyst, the 25 nm pore diameter samples showed good response and recovery properties. However, the 60 nm samples showed unstable and slow response. It was found that the pore size affects the catalyst reaction and consequently, results in changes of the sensitivity to hydrogen.

• 대한전기학회논문지
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• 제40권12호
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• pp.1218-1229
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• 1991

The time optimal position control design can be repeatedly taken from the initial state of a dynamic system to a desired one as fast as possible in the industrial drives. In this case, an induction machine parameters will vary due to temperature, frequency, and saturation effects. In particular, the rotor resistance changes critically with temperature and frequency. These changes affect the command values of the stator current components and slip speed. There is a mismatch between the commanded variables and actual ones of the induction motor drive, and this situation leads to coupling of the vector controller from the plant, i.e. the induction motor . Consequences of such a coupling include the initiation of oscillations of the rotor flux and unsuitable switching of electromagnetic torque for the induction motor servo drive. Therefore, this paper describes a rotor resistance parameter compensating method for the induction motor, And the validity of the proposed design method is confirmed by simulation studies and experiment results.

• 대한치과교정학회지
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• 제37권2호
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• pp.137-149
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• 2007

본 연구의 목적은 모멘트 변화에 따른 건조 환경과 타액 환경에서의 스테인리스강 브라켓과 여러 종류의 교정용 선재 사이의 마찰력을 비교하는 것이었다. 실험에는 $0.022"{\times}0.028"$ 스테인리스강 브라켓과 $0.019"{\times}0.025"$ 스테인리스강, 베타-티타늄, 니켈-티타늄 선재가 사용되었다. 활주 이동될 브라켓에는 0.9 mm 직경의 스테인리스강 선재로 제작된 길이 10 mm의 레버를 부착하였으며 레버에 100 g, 200 g의 추를 부착함으로써 브라켓에 각각 $1000g{\cdot}mm$ $(100g{\times}10mm)$, $2000g{\cdot}mm$ $(200g{\times}10mm)$의 모멘트를 가하고 만능시험기를 이용하여 마찰력을 측정하였다. 모든 조건에서 스테인리스강 선재가 가장 작은 마찰력을 보였으며 베타-티타늄과 니켈-티타늄 선재 사이에서는 $2000g{\cdot}mm$ 모멘트의 인공타액 하의 조건에서를 제외하고는 마찰력의 유의한 차이가 없었다 모든 선재에서 모멘트가 $1000g{\cdot}mm$인 때보다 $2000g{\cdot}mm$일 때 마찰력이 더 컸다. 건조 환경과 타액 환경의 비교에 있어서 $1000g{\cdot}mm$의 모멘트 하에서 인공타액에 의해 스테인리스강 선재의 마찰력은 증가하였으나 베타-티타늄과 니켈-티타늄의 마찰력은 증가하지 않았으며, $2000g{\cdot}mm$의 모멘트 하에서 인공타액에 의해 모든 종류의 선재에서 마찰력이 증가하였다.

• 대한토목학회논문집
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• 제44권1호
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• pp.49-62
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• 2024

급격한 도시화로 인한 지하의 무분별한 개발은 기존 지하매설물의 점검과 교체 그리고 새로운 지하시설물 설치에 지연을 일으키고 있다. 최근에는 체계화된 시스템을 도입하여 지하시설물을 관리하고 있지만, 실제 시공은 현장 여건에 따라서 설계 도면과 다르게 진행되기 때문에 기존 지하매설물의 부정확한 위치 정보로 사고가 끊임없이 발생하고 있다. 한편, 전기비저항 탐사는 전극을 지반에 관입시켜 전극 간 전위차로 지반의 전기저항을 측정하는 방식이며, 비파괴 물리탐사 기법으로서 널리 이용되고 있다. 그리고 다수의 전극 쌍을 이용하여 복잡한 지하 구조를 영상화하고, 딥러닝 알고리즘을 활용한 데이터 해석 기술들이 비약적으로 발전하였지만, 아직 지하매설물의 기하학적 조건에 따른 전기저항 변화를 정량적으로 평가한 기초적인 연구로서는 진행된 바가 없다. 본 연구에서는 전극과 지하매설물의 기하학적 매개 변수 해석을 통해서 전기저항 변화를 평가하였다. 먼저, 이론식과 수치 해석의 전기저항값 차이가 작게 나타난 정량화된 메쉬를 적용하여 3차원 전기저항 수치 해석 모듈을 개발하고, 매설물의 깊이, 크기, 그리고 전극과 매설물 간 이격거리에 따른 매개 변수 해석을 통해서 정상 직류 상태에서 전기저항 변화를 정량적으로 비교하였다. 전기저항은 매설물이 얕은 깊이에 위치하고, 크기가 크고, 전극과의 이격거리가 가까울수록 높게 측정되었다. 추가적으로 전극과 지하매설물 주변에 형성된 전위 및 전류밀도 분포를 분석하여 터미널 전극 주변에서 측정된 전기저항을 고찰하였다.