• 한국미생물·생명공학회지
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• 제25권3호
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• pp.335-337
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• 1997

In this study, we show a convenient MTT assay for detect the susceptibility of yeast-like form of Trichosporon beigelii against antifungal agents. This assay was developed based on mitocondrial respiration by determining reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to formazan. Cells of T beigelii are seeded into 96-well microtiter plates, and antifungal agents, amphotericin B, magainin and CA-ME hybrid peptide were added with various concentrations. After 24 hr incubation, MTT was added, then incubations were continued for 4 hr. Formazan formation was quantified photometrically after extraction of the formazan with acid sodium dodesyl sulfate (SDS). From this assay, we could obtained MICs of antifungal agents against T. beigelii. The presented method can easily be used as an effective methods to assess the antiftingal action of various agents on yeasts with minimal amounts of antifungal agents.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.15-21
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• 2001

An accumulator in hydraulic systems stores kinetic energy during braking action, and then that controls hasty surge pressure. An energy recovery system using accumulator seems to be advantageous for ERBS due to its high energy density. This study suggests a method to decide suitable accumulator volume for ERBS. The method is based upon energy conservation between kinetic energy of moving inertia and elastic energy of accumulator. The energy conversion was analyzed and a simple formula was derived. A series of computer simulation was done to verify effectiveness of the formula. The results of the simulation work were compared with those of experiments and these results show that the proposed design is effective for decision accumulator volume in ERBS.

• Journal of Ship and Ocean Technology
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• 제10권1호
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• pp.27-37
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• 2006

Current loads acting on offshore vessels are important for predicting the hydrodynamic and structural responses of the vessels. It is also true for analyzing the behavior of moored systems under the action of ocean current. Unfortunately there are few standardized current load coefficients for offshore vessels and it is extremely difficult to be applied to arbitrary hull shapes, if any. Therefore current load coefficients for three hull shapes are calculated in this study using a CFD code, which is well known in the shipbuilding industry. In order to validate the present approach, a typical VLCC is taken as numerical example and resulting current coefficients are compared with experiment together with the OCIMF data. The comparison shows a good agreement in the qualitative sense. Two additional models considered herein are a shuttle tanker and a FPSO under deepwater condition $(WD/T{\geq}6)$. The present numerical approach may be utilized for practical design of offshore vessels.

• Wind and Structures
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• 제2권3호
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• pp.201-251
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• 1999

Flexible structures may experience excessive levels of vibration under the action of wind, adversely affecting serviceability and occupant comfort. To ensure the functional performance of a structure, various design modifications are possible, ranging from alternative structural systems to the utilization of passive and active control devices. This paper presents an overview of state-of-the-art measures that reduce the structural response of buildings, including a summary of recent work in aerodynamic tailoring and a discussion of auxiliary damping devices for mitigating the wind-induced motion of structures. In addition, some discussion of the application of such devices to improve structural resistance to seismic events is also presented, concluding with detailed examples of the application of auxiliary damping devices in Australia, Canada, China, Japan, and the United States.

• 소성∙가공
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• 제30권3호
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• pp.149-156
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• 2021

Fine blanking is a high-precision process combining principles of metal stamping and cold forming. Unlike conventional metal stamping, fine blanking uses a special triple action such as V-ring force, counter force, shearing force. This study performed the effect of pocket-shaped compression molding on the mold life of the fine blanking using the 7.4mm thick SM45C material. In order to determine the lifespan of the punch and die in the fine blanking molds, a trial mold was manufactured and various punch materials were selected to perform the mold life test. A study on the life of a fine blanking mold by applying a thick plate material was experimentally performed through a mold test.

• 한국구조물진단유지관리공학회 논문집
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• 제10권1호
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• pp.131-138
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• 2006

일정한 크기의 마찰력을 도입한 가새(FSB)는 에너지를 소산시키는 효과적인 구조 부재이며, 가새의 축력이 마찰력을 넘지 않을 때까지만 탄성 거동을 한다. 본 연구에서는 FSB 개념을 보다 확장시켜서 가새를 죄는 마찰력의 크기를 능동적으로 변화시킬 수 있는 능동 조임 마찰 가새(AFSB)를 착상하여 단자유도 구조물에 적용하고 조화 하중으로 기진시켜 그 거동을 시뮬레이션 하여 FSB와 비교 분석해본다. 이를 위해 간단하고 효과적인 알고리즘을 개발해보았다. 연구 결과, 지반 가속도 값이 그다지 크지 않은 경우, AFSB는 초기에 오우버슈팅이 발생하는 문제만 제외하고 FSB에 비해 효과적으로 진폭과 밑면 전단력을 감소시켰다.

• 한국안전학회지
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• 제35권3호
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• pp.105-115
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• 2020

This study compares the difference of fit factors (FF) and visual acuity according to masks and eyeglasses preferences for 54 participants. We the precautions and behaviors of discomfort when wearing masks of eyewear wearers. Contact lens discomfort and priority action of complaints was investigated Glasses fitting factors is Optical Center Height(OH), Vertex Distance(VD) and Pantoscopic Angle(PA). We measured those factors and expressed by the ratio of standard point and change point. Quantitative fit factor was measured by Portacount Pro+ 8038. Also, we selected to 6 exercises among 8 exercises OSHA QNFT (Quantitative Fit testing) protocol to measure the fit factors. The pass/ fail criterion of FF was set at 100. Visual acuity(VA) test chart is developed by Chunsuk Han was used, Descriptive statistics was performed. Descriptive statistics(SAS ver 9.2), it is used geometric means, Wilcoxon analysis(P=0.05) When wearing the mask preferentially, fit factor(FF) was high according to the step of glasses fitting parameter. on the other hand, when the glasses first choice, the visual acuity(VA) was high. there was no significant difference. In the case of fit factor (FF), mask first choice/ glasses first choice is OH (p=0.671/ p=0.332), VD (p=0.602/ p=0.571) and PA (p=0.549/ p=0.607). Visual acuity (VA), mask first choice/ glasses first choice is OH (p=0.753/ p=0.386), VD (p=0.815/ p=0.557) and PA (p=0.856/ p=0.562). The workers of workplace and office chose glasses but occupational health workers and students chose mask. In case of discomforts, it was suggested to remove the mask and tolerate discomforts. The main discomforts and usual action of lens were dryness, hyperemia, foreign body sensation, ophthalmodynia, decreased vision and glasses wearing. Therefore, it is necessary to develop a mask wearing method education program considering glasses fitting and develop a hybrid model that minimizes inconvenience when wearing glasses and a mask at the same time.

• 한국소음진동공학회논문집
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• 제17권10호
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• pp.967-975
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• 2007

A rotordynamic analysis was performed with a dry vacuum pump, which is a major equipment in modern semiconductor and LCD manufacturing processes. The system is composed of screw rotors, lobes picking air, helical gears, driving motor, and support rolling element bearings of rotors and motor. The driving motor-screw rotor system has a rated speed of 6,300 rpm, and was modeled utilizing a rotordynamic FE method for analysis, which was verified through 3-D FE analysis and experimental modal analysis. As loadings on the bearings due to the gear action were significant in the system considered, each resultant bearing load was calculated by considering the generalized forces of the gear action as well as the rotor itself. Each resultant bearing loading was used in calculating each stiffness of rolling element bearings. Design goals are to achieve wide separation margins of lateral and torsional critical speeds, and favorable unbalance responses of the rotor in the operating range. Then, a complex rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds, whirl natural frequencies and mode shapes, unbalance responses under various unbalance locations, and torsional interference diagram. Results show that the entire system is well designed in the operating range. In addition, the procedure of rotordynamic analysis for dry vacuum pump rotor-bearing system was proposed and established.

• International Journal of Industrial Entomology and Biomaterials
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• 제9권2호
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• pp.279-281
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• 2004

Components of genetic variation were estimated for five metric traits using 24 biparental progenies (N. C. Design III) generated from F$_2$ generation of a commercial bivoltine silkworm hybrid, SH$_{6}$${\times}$NB$_4$D$_2$. Variance due to additive ($\sigma$$^2$A) and dominance ($\sigma$$^2$D) gene effects was significant for single cocoon weight and shell weight. However, magnitude of former was greater than latter indicating preponderance of additive gene action in the inheritance of these two traits. Average degree of dominance was in the range of partial dominance for all the traits. High estimates of heritability (ns) indicated operation of genes with large additive effects, hence, scope exists for improvement of present populations through a few cycles of selection.n.

• 한국콘텐츠학회논문지
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• 제18권1호
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• pp.314-326
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• 2018

본 연구의 목적은 14명의 읽기장애아동 부모를 대상으로 하이브리드 모바일 읽기 게임의 사용성에 대하여 평가한 것이다. 읽기 게임은 아동의 읽기 발달 과정에 따라 총 6단계(자모음 익숙해지기, 통글자 익히기, 자모음 결합하기, 단어 읽기, 음운 규칙, 읽기 자동화)로 구성되었다. 본 사용성 검사에서는, 부모들이 1단계부터 3단계의 읽기 게임 앱 내용을 경험해보고, 일반적인 디자인 설계 및 보편적 학습설계를 5점 평정척도로 평가하였다. 일반적인 디자인에 대한 사용성 검사 결과(총 18개 항목)를 살펴보면 상호작용 설계, 교수적 설계, 인터페이스 설계 순으로 높게 평가되었다. 보편적 학습설계 측면(총 9개 항목)의 검사 결과로는 다양한 방식의 표상을 제공, 다양한 방식의 행동과 표현수단을 제공, 다양한 방식의 학습 참여를 제공하는 것 순으로 사용성이 높게 평가되었다. 마지막으로 앱의 개선점, 현장에 제공하는 시사점, 미래연구를 위한 제언들이 논의되었다.