• 한국지역사회생활과학회지
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• 제21권4호
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• pp.595-603
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• 2010

The present study was performed on humans to investigate the physiological strain of wearing protective clothing for shielding electromagnetic waves and to compare control clothing that are currently on the market and new clothing that are developed for improving thermal comfort and material weight. Experiments were conducted in a climatic chamber of $28.8{\pm}0.6^{\circ}C$, $37{\pm}5%$RH under three differed experimental clothing conditions: None, Control, New. The results were as follows. Mean skin temperature and rectal temperature in New were significantly lower than that in None and Control (p<.05). The temperature and humidity inside clothing were lower in None (p<.05). Total weight loss was lower in New. Thermal sensation and thermal comfort were less hot and more comfortable in New than those in Control. It was concluded that wearing the protective clothing for shielding electromagnetic waves affects physiological responses such as distribution of body temperature, sweat rate, etc.

• 한국산학기술학회논문지
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• 제20권5호
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• pp.627-635
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• 2019

코딩 교육용 드론은 비행의 기초 원리를 체험하는 것뿐 아니라, 주로 아두이노(Arduino) 기반의 프로그래밍을 통해 드론을 제어하고 조종할 수 있도록 개발된 드론이다. 교육용 드론의 특성상 주 사용자는 드론 조종에 미숙한 학생들이기 때문에 드론과 외부 물체와의 충돌이 빈번하게 발생하여 드론 기체의 손상 비율이 높은 문제점이 있다. 본 연구에서는 교육용 드론 기체에 대한 구조 동역학 기반의 충돌 시뮬레이션 방법을 통해 드론의 구조적 안정성을 평가하였다. 약 240,000개의 4면체 요소를 갖는 해석 모델을 사용하여 $0^{\circ}$, $+15^{\circ}$, $-15^{\circ}$의 충돌 각도에 따른 3가지 케이스에 대해 충돌 시뮬레이션을 수행하였다. 3차원 구조물의 동적 거동 시뮬레이션에 탁월한 기능을 제공하는 ANSYS LS-DYNA를 활용하여 드론이 4 m/s의 속도로 벽에 충돌했을 때 주요 관심 부분인 드론 상 하부, 링 조립체에 발생하는 응력 분포 및 변형률을 분석하였다. 주요 관심 부분의 등가 응력에 따른 안전율은 0.72~2.64, 항복 변형률 기준 안전율은 1.72~26.67의 범위로 도출되었다. 이러한 안전율을 기준으로 재료 물성에 따른 항복 변형률과 종국 변형률을 초과하는 응력이 발생하는 부분에 대한 구조 안정성 확보를 위해 설계 보강이 필요한 부분을 제시한다.

• Mycobiology
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• 제44권2호
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• pp.99-104
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• 2016

Candida spp. is an invasive infectious fungus, a major risk factor that can increase morbidity and mortality in hospitalized patients. In this study, 2,508 Candida spp. were isolated from various clinical specimens collected from university hospitals from July 2011 to October 2014. They were identified in order to determine isolation frequencies and characteristics by specimen, gender, age group, year, season, and month. The strain-specific isolation rate of Candida spp. is in the order of Candida albicans (1,218 strains, 48.56%), Candida glabrata (416 strains, 16.59%), Candida utilis (305 strains, 12.16%), Candida tropicalis (304 strains, 12.12%), and Candida parapsilosis (116 strains, 4.63%) and these five species accounted for more than 94% of the total strains. Of the specimens, Candida spp. were most frequently isolated from urine-catheter, followed by urinevoided, blood, sputum, other, open pus, vaginal discharge, Tip, ear discharge, bronchial aspiration and bile, in that order. Looking at the age distribution, the detection rate of patients in their 60s and older was significantly higher at 75.8% (1,900/2,508). The detection rate of patients in their 20s and younger was shown to be very low at 2.55% (64/2,508). By year, the detection rate of non-albicans Candida spp. showed a tendency to gradually increase each year compared with C. albicans. As isolation of Candida spp. from clinical samples at the specie level can vary depending on characteristics of the patient, sample, season, etc., continual studies are required.

• 소성∙가공
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• 제32권6호
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• pp.311-320
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• 2023

Recently, lightweight of automotive parts has been required to solve environmental problems caused by global warming. Accordingly, research and development are proceeded on manufacturing of parts using aluminum that can replace steel for lightweight of the automotive parts. In addition, high strength aluminum can be applied to body parts in order to meet both requirements of lightening and improving crash safety of vehicle. In this study, hot blow forming of roof side rail is employed to manufacturing of the automotive parts with high strength aluminum tube. In hot blow forming, longer forming times and excessive thinning can be occurred as compared with conventional manufacturing processes. So optimization of process conditions is required to prevent excessive thinning and to uniformize thickness distribution with fast forming time. Mechanical properties of high strength aluminum are obtained from tensile test at high temperature. These properties are used for finite element(FE) analysis to investigate the effect of strain rate on thinning and thickness distribution. Variation of thickness was firstly investigated from the result of FE analysis according to tube diameter, where the shapes at cross section of roof side rail are compared with allowable dimensional tolerance. Effective tube diameter is determined when fracture and wrinkle are not occurred during hot blow forming. Also FE analysis with various pressure-time profiles is performed to investigate the their effects on thinning and thickness distribution which is quantitatively verified with thinning factor. As a results, optimal process conditions can be determined for the manufacturing of roof side rail using high strength aluminum.

• 한국환경보건학회지
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• 제29권2호
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• pp.94-102
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• 2003

This study was carried out to investigated the distribution and characteristics of Vibrio spp. isolated from fish and shellfish, seawater and brackish water samples collected from Pohang, Uljin, Yeongduk and Gyeongju in Gyeongbuk Province from April 2000 to October 2000. Total 155 strains of genus Vibrio were isolated from 439 collected samples, and numbers of isolated strains of V. parahaemolyticus and V. vulnificus were 140 and 15, respectively. The isolation rate from the samples collected in Pohang was the highest as 41.5% (76 strains), and wat the highest as 71.4% (30 strains) in brackish water, and was the highest as 55.7% (34 strains) in August. And the optimal pH, temperature, and NaCl concentration for growth of V. parahaemolyticus and V. cholerae were 8.0, 3$0^{\circ}C$ and 2.0％, respectively. In a resistance test for environmental factors, heat and cold resistants of V. parahaemolyticus were higher than those of V. vulnificus, withstanding for 15 minutes at 6$0^{\circ}C$ and 6 days at -18$^{\circ}C$. The pH range for existence of V. parahaemolyticus and V. vulnificus were 4.5~l1.0 and 4.5~10.0, showing the similar resistance to pH. V. parahaemolyticus and V. vulnificus could grow in media containing up to 10.0% and 7.0% NaCl, respectively, Salt-tolerance of V. parahaemolyticus was higher than that of V. vulnificus. In an antibiotics sensitivity test against 16 strains of V. parahaemolyticus, twelve strains were resistant to ampicillin, eight strains were resistant to cephalothin. one strain was resistant to streptomycin, and one strain was resistant to ticarcillin.

• 센서학회지
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• 제31권6호
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• pp.411-417
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• 2022

In this paper, we propose a sensor with a C-shaped load cell to detect force change when a person sitting on the chair in an electrical transport-convenience vehicle is pushing ground by both heels. The load cell built in the vehicle is mechanically deformed by the vertical force owing to the human weight and the horizontal force by ground-pushing feet. The deformation rate of the load cell and its distribution are simulated using finite element analysis. In the simulation, the applied loads are preset in the range of 10 kg - 100 kg with a step size of 10 kg, and the ground-pushing force by feet is increased to 40 N with a step size of 5 N with respect to each applied load level. The resistance change of the load cell was observed to be linear in simulation as well as in measurement. the maximum difference between simulation and measurement was 0.89 % when the strain gauge constant was 2.243. The constant has a large influence on the difference. The proposed sensor was fabricated by connecting an instrument amplifier and a microcontroller to a load cell and used to detect the force by ground-pushing feet. To detect foot driving, the reference signal was set to 130% of the load, and the duration of the sensor output signal exceeding the reference signal was set to 0.6 s. In a test of a vehicle built with the proposed sensor, the footpushing force by the worker could be successfully detected even when the worker was working.

• 한국연초학회지
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• 제2권1호
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• pp.17-27
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• 1980

143개의 여러가지 시료에서 니코틴 분해세균의 분포를 조사하고 니코틴 배지에서 생장능이 우수한 34균주를 선별하여 균주의 생물학적 특성과 니코틴 분해력을 조사함과 동시에 니코틴 분해력이 가장 우수한 균주를 선정하여 동정하였다. 니코틴 분해세균은 유기물이 풍부한 토양과 담배씨, 부리에 많이 분포되어 있었고 선별된 34균주는 Arthrobacter 4주, Pseudomonas (non-pigmented) 11주, Pseudomonas (Pigmented) 2주, Alkaligenes 6주, Chromobacter 5주, Listeria 2주, Achromobacter 4주 등으로 분류되었다. 니코틴 분해력에 있어서는, Pseudomonas와 Alkaligenes가 다른 속(genus)보다 높고, 서식지 별로 비교해 보면 담배씨와 뿌리에서 분리된 균주가 우수했으며 가장 우수한 균주는 97.l%의 분해율을 나타내는 균주번호 NCT27로서 Pseudomonas putida로 동정되었다.

• 한국의류학회지
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• 제32권7호
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• pp.1129-1136
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• 2008

The gaiter is one of the personal protective equipments worn in various industrial sites. This study was performed on humans to investigate the physiological strain of wearing gaiters and to compare control gaiters that are currently on the market and new gaiters that are developed for alleviating heat stress. Experiments were conducted in a climatic chamber of WBGT $30.0\pm0.7^{\circ}C$ under five differed experimental conditions: None, Control A, Control B, New A, New B. The results were as follows. The temperature inside gaiters was significantly lower in both New A and New B than in both Control A and Control B and the difference between news and controls was 1$^{\circ}C$ (p<.01). The humidity inside gaiters in both New A and New B were higher than that in Control A, and lower than that in Control B (p<.01). The outermost surface temperature of the gaiter was the lowest in None and it increased in the following order: New B < New A < Control A < Control B. Mean skin temperature was higher by 0.14$^{\circ}C$ in wearing gaiters than in no gaiters. Skin temperatures in lower body were lower in Control than in New and skin temperature in upper body were higher in Control than in New (p<.01). Local sweat rate, total weight loss and subjective sensations did not show a significant difference according to the gaiters. It was concluded that wearing gaiters affected distribution of skin temperature and local sweat rate.

• 한국균학회지
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• 제41권2호
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• pp.91-96
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• 2013

기존 큰느타리버섯 품종의 단점을 개선하고자 단교배를 통하여 여러 가지 형질을 복합적으로 지니는 품종을 육성하고자 애린이와 나 계통을 모본으로 선택하고, 이들 계통으로부터 유래한 단핵균사간의 단교잡을 실시하였다. 애린이10${\times}$나5계통이 수확량, 생육소요일수, 전체적인 모양에서 다른 계통보다 우수하였고 이 계통을 애린이 3으로 명명하였다. 애린이 3은 큰느타리2호보다 수확일이 2~3일 빠르고, 수확량도 110.5 g으로 기존품종의 108%수준이었다. 갓직경과 대두께의 비율은 1.8로 기존품종의 2.1보다 우수하여 수확이나 유통시 버섯의 손상이 적을 것으로 사료된다. 소비자에 대한 맛과 구매의향 조사에서 육성계통은 31.4%가 매우우수, 53.3%가 우수로 평가한 반면 기존 품종은 20.7%가 매우우수, 34.8%가 우수로 판정하였다. 구매의향도 총 86.9%가 높음 이상이어서 기존 품종의 46.8%보다 높아 시장성이 높을 것으로 사료된다.

• 한국유체기계학회 논문집
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• 제15권3호
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• pp.12-18
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• 2012

The Lattice Boltzmann Method has developed for solving the Boltzmann equation in Cartesian domains containing immersed boundaries of arbitrary geometrical complexity moving with prescribed kinematics. When a immersed boundaries are sweeping the fixed fluid node, refilling the node information in a vicinity of fluid nodes is one of the important issues in Lattice Boltzmann Method. In this study, we propose a simple refill algorithm for the particle distribution function based on a proper velocity, density and strain rate to enhance accuracy and stability of the method. The refill scheme based on a asymptotic analysis of LBGK model has improved accuracy than interpolation schemes. The proposed scheme in this study is validated by the simulations of an impulsively started rotating circular cylinder to investigate adaptability for fluid-structure interaction (FSI) problem. This refill scheme has improved stability and accuracy especially at high Reynolds number region.