• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1709-1714
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• 2004

Pressurization system of a 50m unmanned airship was manufactured according to the detailed design. In this paper. the whole procedures including system design. simulation and fabrication were described. The fabricated part were ground tested to check compliances with design requirements. Ground tests include operational tests, leakage tests, endurace tests and low temperature environmental tests. Results shows pressurization system of a 50m unmanned airship meets design requirements. Currently. pressurization system is installed to the KARI airship, Via 50m and performance verification through the flight tests are being conducted.

• 대한토목학회논문집
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• 제33권2호
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• pp.631-642
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• 2013

현장지반의 공학적 특성을 파악하기 위한 콘 관입시험(Cone Penetration Test; CPT)은 원지반의 연속적인 강도 특성을 분석하여 다양한 지반변수를 손쉽게 획득할 수 있다는 점에서 널리 활용되고 있으며, 원심모형실험에서도 널리 활용되고 있다. 본 연구에서는 원심모형실험에서 콘선단저항치를 계측할 수 있는 직경이 10 mm인 소형 콘을 개발하고 원심모형실험에서의 적용성을 평가하였다. 개발된 콘으로 4자유도 로봇을 활용하여 원심모형 가속 상태에서 콘 관입시험을 수행하였다. 이 때, 원심가속도 수준을 4회 변화시켜 다양한 유효응력상태에서 콘 관입시험을 실험을 수행하였다. 그 결과, 얕은 관입깊이의 동일한 유효응력에서 콘 선단저항치는 g-level에 영향을 받으며, 선단저항치가 임계 깊이 도달하는 깊이는 g-level과 상대밀도가 커질수록 깊어짐을 확인하였다. 또한, 각 실험에서 임계 깊이에 도달한 선단저항치와 실내실험에서 획득한 지반물성을 이용하여 기존 경험식과 비교하였다.

• 한국환경보건학회지
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• 제30권3호
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• pp.185-190
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• 2004

Acute aquatic toxicity of effluents discharged from five dyeing plants in Gyeong-gi province were evaluated to assess whether the current Korean water quality standards(KWQS) could protect aquatic life. Chemical analyses of all parameters regulated under KWQS, except for E-coli, were also carried out to determine regulation compliance of the samples. All the effluent samples were satisfied with KWQS except for the color in only one sample. In acute Daphnia magna toxicity tests, significant mortality was observed in one of five samples and EC50 was 12.1%(95% confidence interval 9.1-16.2), which was in compliance with KWQS. The result of the Microtox assay indicated that acute microbial toxicity existed in effluents from three out of five plants, two of which were in compliance with KWQS. The agreement between regulation compliance of chemical concentrations of effluent and observed toxicity from various biological toxicity tests was very poor to fair (kappa = 0.194~0.250). The data presented suggest that exposure to dyeing wastewater which were in compliance with Korean water quality standards may not be safe to aquatic biota, and multiple tropical levels should be considered in aquatic toxicity monitoring of dyeing industry.

• Steel and Composite Structures
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• 제24권2호
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• pp.201-211
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• 2017

This study evaluates the reliability of present European codes in predicting the collapse load of columns made with perforated cold-formed steel (CFS) profiles under combined axial load and bending. To this aim, a series of experimental tests on slender open-section specimens have been performed at varying load eccentricity. Preliminarily, stub column tests have also been performed to calculate the effective section properties of the investigated profile. By comparison of experimental data with code-specified M-N strength domains, the authors demonstrate that present code formulations may underestimate the collapse load of thin-walled perforated open sections. The study is the first step of a wider experimental and numerical study aimed at better describing strength domains of perforated CFS open sections.

• 한국환경성돌연변이발암원학회지
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• 제16권2호
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• pp.103-108
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• 1996

The mutagenic potential of rHu-EPO was evaluated using the short-term genotoxicity tests including Ames, chromosome aberration and micronuclei tests. In Salmonella typhimurium assay, rHu-EPO did not show any mutagenic response in the absence or presence of S9 mix with TA98, TA100, TA1535, and TA1537. In chromosome aberration test, rHu-EPO did not show any significant effect on Chinese Hamster Ovary(CHO) cells compared with control. In micronucleus test using male ICR mice, a dose-dependence increase in the frequency of micronucleuted polychromatic erythrocytes(MNPCEs) was observed in bone marrow cells treated with rHu-EPO. However, it was related to the secondary effect of rHu-EPO and the number of MNPCEs was equal to spontaneous frequency. These results indicate that rHu-EPO does not show any positive response in short-term genotoxicity assays.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2010년 추계학술대회 논문집
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• pp.99-107
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• 2010

A permanent deformation model was developed in this study based on the shear properties of asphalt mixtures such as cohesion and friction angle. Triaxial compressive strength (TCS) and repeated load permanent deformation (RLPD) tests on the three types of asphalt mixtures are performed at various loading and temperature conditions to correlate shear properties of asphalt mixtures to rutting performance. It is observed from the tests results that the ratio of shear stress to strength accurately identifies the mixture rutting performance. It could take care of not only mixture types but also load and temperature conditions dependences. Three different versions of the permanent deformation model based on different input levels are proposed and verified using the tests data. The proposed model based on the ratio of shear stress to strength can successfully predict the permanent deformation of various asphalt mixtures all the way up to the 10% of permanent strain including all three stages of permanent deformation in a wide range of loading and temperature conditions without changing model coefficients.

• 한국안전학회지
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• 제26권2호
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• pp.48-61
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• 2011

In this study, static tests were done on the joints between precast manholes and the joints between manhole and sewer. The static loading tests in not only elastic range but also ultimate state of model members were carried out to investigate the bond strength and ultimate load of a joint of precast manholes. Specimens were tested in bending, horizontal shear, horizontal shear of circumferencial direction and direct tension. The results of tests indicated good structural performance of the joints between precast manholes and the joints between manhole and sewer.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.940-951
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• 2009

A comparative study on dynamic and static measurement of initial stiffness was conducted. Because soil stiffness decreases even at very small strains, the initial stiffness has been measured by dynamic tests using shear wave velocity measurement. On the other hand, due to the advance of local strain measurement, the triaxial testing device is capable of measuring the static initial stiffness. It has been known that initial stiffness measured by static triaxial tests is generally lower than that measured by dynamic tests possibly due to the limitation of static measurement of displacement at very small strains. This study presents experimental results indicating that the elastic shear moduli could be the same both in dynamic and static measurements owing to the soil anisotropy induced by anisotropic stresses.

• 한국환경복원기술학회지
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• 제5권5호
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• pp.11-21
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• 2002

A series of model tests is performed to evaluate the relationship between soil and a buried pipe in soil undergoing lateral movement. As the result of the model tests, a wedge zone and plastic flow zones could be observed in front of the pipe. And also an arc failure of cylindrical cavity could be observed at both upper and lower zones. Failure shapes in both cohesionless and cohesive soils are nearly same, which was investigated failure angle of $45^{\circ}+{\phi}/2$. In the cohesionless soil, the higher relative density produces the larger arc of cylindrical cavity. On the basis of failure mode observed from model tests, the lateral earth pressure acting on a buried pipe in soil undergoing lateral movement could be applying the cylindrical cavity extension mode. The deformation behavior of soils was typically appeared in three divisions, which are elastic zones, plastic zones and pressure behavior zones.

• Environmental Engineering Research
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• 제10권1호
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• pp.1-6
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• 2005

Hexavalent chromium in aqueous solutions was successfully removed via sorption and reduction in the presence of waste leaves. Cr(VI) removal followed a first-order reaction, and removal rates were proportional to the amount of waste leaves used in the tests. Most of Cr(VI) were removed via sorption in early stages of the tests, but the reduction reaction played a significant role in Cr(VI) removal later. Solution pHs were continuously decreased due to the microbial activity, which was induced from the microorganisms attached on waste leaves. The decreased solution pHs further enhanced the sorption and reduction of Cr(VI). To characterize the microorganisms found in the tests, a denaturing gradient gel electrophoresis (DGGE) method was used. The majority of microorganisms were composed of Bacillus sp. which can reduce Cr(VI). Thus, waste leaves can be effective reactive media for the treatment of Cr(VI) in the subsurface.