• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.595-600
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• 2009

Passengers in a vehicle feel uncomfortable due to squeal noise. Squeal noise, a kind of self-excited vibration, is generated by the friction force between the disc and the pad of the automobile. In this paper, modal analysis of wheel brake system was performed in order to prediction of squeal phenomenon. It was shown that the prediction of system instability is possible by FEM. Finite element model of that brake system was made. Some parts of a real brake was selected and modeled. The normal mode analysis method performs analyses of each brake system component. Experiment of modal analysis was performed for each brake components and experimental results were compared with analytical result from FEM. The complex eigenvalue analysis results compared with braking test. The analysis results show good correlation with braking test for the squeal frequency at an unstable mode.

• Computers and Concrete
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• 제20권1호
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• pp.39-47
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• 2017

In this paper, mode I fracture toughness of rock was determined by direct and indirect methods using Particle Flow Code simulation. Direct methods are compaction tension (CT) test and hollow centre cracked quadratic sample (HCCQS). Indirect methods are notched Brazilian disk (NBD) specimen, the semi-circular bend (SCB) specimen, hollow centre cracked disc (HCCD), the single edge-notched round bar in bending (SENRBB) specimen and edge notched disk (END). It was determined that which one of indirect fracture toughness values is close to direct one. For this purpose, initially calibration of PFC was undertaken with respect to data obtained from Brazilian laboratory tests to ensure the conformity of the simulated numerical models response. Furthermore, the simulated models in five introduced indirect tests were cross checked with the results from direct tests. By using numerical testing, the failure process was visually observed. Discrete element simulations demonstrated that the macro fractures in models are caused by microscopic tensile breakages on large numbers of bonded discs. Mode I fracture toughness of rock in direct test was less than other tests results. Fracture toughness resulted from semi-circular bend specimen test was close to direct test results. Therefore semi-circular bend specimen can be a proper test for determination of Mode I fracture toughness of rock in absence of direct test.

• 동의생리병리학회지
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• 제22권3호
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• pp.619-623
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• 2008

The purpose of this study was to observe the effects of antibacterial activities on various medicinal herbs. Medicinal herbs used this study was Curcuma aromatica, Scutellaria baicalensis, Angelica dahurica, Platycodon grandiflorum, Houttuynia corolata, and Forsythia saxatilis. To evaluation of the antibacterial effect, we used S. gallinarum(ATCC 9184), S. typhimurium(SAL-13, France), S. enteritidis (ATCC 10376), Escherichia coli(E-62, O78), and S. gallinarum(E. coli). Extracts from each medicinal herbs divided into 100mg/ml, 50 mg/ml, 25 mg/ml, and 12.5 mg/ml. Antibacterial activities achieved by the paper disc test. Antibacterial activities was showed at extracts from Scutellaria baicalensis, Houttuynia corolata, Forsythia saxatilis, but little found at Curcuma aromatica, Angelica dahurica, Platycodon grandiflorum.

• 한국식품영양과학회지
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• 제42권3호
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• pp.441-449
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• 2013

본 연구는 건조 오미자 추출액을 이용하여 오미자 식초를 발효하였다. 산패한 오미자 와인에서 식초산균 OV1과 OV2를 분리하고 분리균의 식초산 생성능력을 비교하였다. 분리균 OV1은 알코올농도 8%까지 발효 가능하였으며, 알코올 농도 6%의 오미자 와인으로부터 산도 5.21%의 식초를 발효하였다. 발효 오미자 식초는 시판 중인 타 식초에 비하여 관능성이 보다 우수한 것으로 평가되었다. 오미자 와인 및 식초의 항균력을 paper disc법으로 검정한 결과 식초는 4종의 검정균(B. subtilis, S. aureus, E. coli 및 P. fluorescens)에 대하여 직경 9.5~17.00 mm의 clear zone을 형성한 반면에 오미자 와인은 S. aureus와 P. fluorescens에 대해서만 clear zone을 생성하였고 clear zone의 직경 또한 9.5 mm 이하로 추출물과 비슷하였다. 오미자 와인 및 오미자 식초의 DPPH free radical 소거능은 오미자 와인(80배수)이 70.25%로 발효 전 추출액에 비하여 약 1.6배 증가하였으나 오미자 식초는 추출액과 비슷한 수준이었으며, 아질산염 소거능 또한 와인에서 높고 식초에서 낮아지는 경향을 나타내었다. 이상의 결과로부터 보당한 건조 오미자 추출액을 사용하여 기호성과 기능성을 갖춘 고품질의 식초를 제조할 수 있는 것으로 판단된다.

• 한국소음진동공학회논문집
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• 제19권10호
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• pp.996-1002
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• 2009

Elimination of squeal noise occurred during brake application is an important task for the improvement of comforts in an industrial forklift. In this paper, a test rig was developed which was possible for testing of brake noise and an experimental measurement on squeal noise was performed. The causes of the brake noise are identified by experimenting how the factors such as automatic transmission fluid and rpm of drive axle affect the squeal. In order to identify the squeal characteristics, the signal analyses for noise are performed by using frequency spectrums. Also, brake test using a forklift was carried out to confirm the reliability of test results by using a test rig comparing with the occurrence of squeal noise. Experimental results showed that the tendencies of occurrence of squeal noise are well agreed at two test methods by using the test rig and forklift.

• Applied Biological Chemistry
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• 제41권8호
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• pp.600-604
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• 1998

Methanol extracts from 53 species of oriental medicinal plants in 34 families were tested for their fungicidal activities against Pyricularia grisea, Rhizoctonia solani, Phytophthora capsici, Phytophthora infestans, Collectotrichum dematium, Botryospaeria dothidea, Fusarium oxysporum f. sp. cucumerinum, Botrytis cinerea, Puccinia recondita, and Erysiphe graminis. In in vitro study using impregnated paper disc method, the efficacy varied with both plant pathogen and plant species tested. Methanol extracts of Asarum sieboldii roots, Sinomenium acutum roots, Pinus densiflora leaves, Rheum undulatum root barks, Coptis japonica roots, and Phellodendron amurense barks showed potent fungicidal activities against the various pathogens when treated with 10 mg/disc. In a whole plant test, methanol extracts of P. densiflora leaves and roots and C. japonica roots were highly effective against a variety of plant pathogens. As a naturally occurring fungicide, P. densiflora- and C. japonica-derived materials could be useful as new fungicidal products against various plant diseases induced by plant pathogenic fungi.

• Applied Biological Chemistry
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• 제41권8호
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• pp.605-607
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• 1998

A total of 28 traditional drinks derived from 23 plant species in 19 families were tested for their in vitro growth-inhibiting effects against Bifidobacterium adolescents, Bifidobacterium bifidum, Lactobacillus acidophilus, Lactobacillus casei, Clostridium perfringens, and Escherichia coil using a paper disc agar diffusion method under anaerobic condition. The responses varied with bacterial strain, plant species and tissue sampled. In a test with C. perfringens at 5 and 10 mg/disc, potent growth inhibition was produced from the extracts of Eucommia ulmoides stems, Pinus densiflora leaves and shoots, Thea sinensis leaves (green and oolong teas) and Zingiber officinale roots. All materials tested did not adversely affect the growth of bifidobacteria, lactobacilli, and E. coli. These results may be an indication of at least one of the pharmacological activities of these plant-derived drinks.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.61-67
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• 2013

In this paper, it was studied how the critical speed which could occur hot judder due to disk temperature. Through the dynamometer experiment, we measured the critical velocity and surface temperature when the hot judder occur on the disk break. Also with the critical velocity theory equation and the temperature change graph of factors which used in the equation, we was induced experiment equation including theory equation and experiment values. And it has compared with the method which approach as linea. From this, we predicted the change of critical speed which could occur hot judder due to disk temperature. In addition, critical speed graph has compared with actual driving speed and disc temperature at a vehicle test. Therefore it was estimate to possibility of arising hot judder.

• 자동차안전학회지
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• 제12권2호
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• pp.7-13
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• 2020

Recently, there is a big issue of downsizing on brake system according to fuel efficiency and regenerative braking cooperation control. Especially, small cars have improved in a variety ways such as electric vehicle and smart car compared to previous small cars. So, small brake system is strongly required in the car industry. A new small brake system for light compact vehicles was proposed in this paper. For this system, the solid type disc and caliper were newly developed. And the important design factors were considered to reduce brake size. First, we calculated the temperature rise of disc through heat capacity formula and CAE analysis. Second, we analyzed the housing and carrier stiffness of caliper to select the reasonable condition. Finally, the superiorities of the developed brake system were verified by heat capacity, consumption liquid level, braking feeling, judder, wear test and regenerative braking cooperation control analysis. A developed brake system is expected to be useful for brake system of light compact platform.

• 비파괴검사학회지
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• 제24권5호
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• pp.465-475
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• 2004

본 논문은 두 편으로 구성된 스마트 능동 레이어(smart active layer, SAL) 센서 개발에 관한 첫 번째 논문으로, 구조 내에 발생하는 균열 및 손상에 의한 탄성파 검출을 위한 SAL 센서의 이론 및 개념을 연구하였다. 본 SAL 센서의 개발을 위해, 첫째, 탄성파의 기본 이론을 고찰하였고, 둘째, 이론적 토대 위에 단일 압전 disc의 유한요소해석법(finite element analysis, FEA)을 이용하여 탄성파 검출 센서로서의 가능성을 검증하였고, 셋째, 몇 종류의 압전 disc 센서와 상용 음향방출(acoustic emission, AE) 센서를 연필심 파괴시험을 통해 상호 성능을 비교하여 실험적으로 그 가능성을 확인하였다. 또한 수 개의 센서를 일정한 거리로 분포시켜서 구조물 결함의 효과적 검출 및 위치 표정이 가능한 스마트능동레이어 센서의 개념연구를 수행하였다.