• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2006년도 학술발표대회 논문집
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• pp.27-31
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• 2006

Rubber hoses for automobile radiators are apt to degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under thermal and mechanical loadings. The aging behaviors of the skin part of the hoses due to thermo-oxidative and electro-chemical stresses were experimentally analyzed. Through the thermo-oxidative aging test, it was shown that the surface hardness IRHD(International Rubber Hardness Degrees) of the rubber increased with a considerable reduction of failure strain as the aging time and temperature were large. On account of the penetration of coolant liquid into the skin part the weight of rubber specimens influenced by electro-chemical degradation (ECD) test increased, whereas their failure strain and IRHD hardness decreased. The hardness decreased further as the test site on the hose skin approached to the negative pole.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.469-472
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• 2006

Amount used of admixture fare is increasing for concrete economic efficiency and ability security. Security of economic efficiency and ability can expect by use of this admixture fare but is displaying a lot of problems on early age strength hold by hydrate delay relatively. Specially, in the case of construction site, concrete strength can speak that interrelation is high with mold removal of forms time. Therefore, is economical and need examination of plan that can secure robber within 3 days using admixture fare such as fly ash and blast furnace slage differential speech to secure function. In this study, adding liquid admixture within 1% of a binding agent quantity to examine these problem with physical characteristic after hardening ago specially, strength change at standard and air dry curing of observed change in priority. Air dried and water curing total strength enhancement effects appeared by thing which is in case of add test result liquid admixture by below 1% and strength deputy by passage of age could know is not big.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1291-1298
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• 2005

Shotcrete for the support of tunnel can contact with groundwater. The hazardous components in the groundwater cause the corrosion of shotcrete. Also, the hazardous components may deteriorate the engineering properties of shotcrete, such as compressive strength, bond strength, and flexural strength. The more the effect of the hazardous components on the shotcrete may increase, the more the stability of tunnel structure may decrease. It was analyzed to find the hazardous components in the ground water. The uniaxial compressive strength test, XRD, SEM were conducted to evaluate the durability and corrosion of shotcrete. These tests were performed on shotcrete specimens at 2, 4, 8, and 16 weeks. The specimens were immersed in various chemical solutions including hazardous components after the specimens were made at the construction site.

• 한국지반환경공학회 논문집
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• 제14권3호
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• pp.13-17
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• 2013

Determination of geotechnical characteristics of soil is either to use the field samples to measure the characteristics of soil through laboratory test or measuring the characteristics directly in the field. Field test can be derived similar value by considering characteristics of site and laboratory test can be confirmed the characteristic of soil by testing with field samples. This article describes relative density as the measure of compaction for cohesionless soils and presents several simple and mathematical relationships to help engineers estimate needed parameters for relative density calculations. The main purpose of this research is to investigate possible correlations between coefficient of uniformity, coefficient of curvature, maximum and minimum void ratio, mean grain size. Results show a linear relationship between the minimum and maximum void ratios and a power function relationship between coefficient of uniformity and the limiting void ratios. Void ratio range, which is the difference between the maximum and minimum void ratios, appeared to be log normally distributed but showed no simple mathematical fit to the data. these results were shown to help engineers estimate needed parameters for relative density calculations.

• 한국군사과학기술학회지
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• 제12권2호
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• pp.146-151
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• 2009

It is known that muzzle flash can be generated by the reaction between the oxygen in the air and unburned gunpowder contained in the propellant gas if a barrel is not long enough to burn gunpowder fully inside of the barrel. A hugh muzzle flash, which is a characteristic of small arms with short barrel length, disturbs a shooter in aiming at the target at night by making the shooter blind for a while and endangers the shooter's life by revealing firing position to enemies. In addition, the heat of muzzle flash can deteriorate the performance of thermal sights, which are attached to small arms for effective night combat. In this paper, flash suppressors of different shapes were designed for a newly developed 5.56mm caliber rifle with short barrel length and the performance of each flash suppressor to reduce the muzzle flash was compared by on-site test firing. Through the test firing, a highly efficient design of flash suppressor for reducing the muzzle flash was identified. The result of the paper can be referred when designing flash suppressors for small arms with short barrel length.

• 한국구조물진단유지관리공학회 논문집
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• 제5권3호
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• pp.173-180
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• 2001

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current, methods (such as LVDT, dial gage, optical displacement transducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by laboratory(simple reinforced concrete beam) and field test. By this test, we proposed correction factor to estimate deflection of reinforced concrete beam after cracking, and analyze about the generation of correction factor. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.381-386
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• 2001

In many countries the slab track of railroads is mostly applied on the railroad bridges and tunnels, however it hasn't been constructed in the tunnel in Korea. Presently the Korea high speed railway construction authority is planning to construct slab track in the tunnels to minimize the cost of maintenance and repair. In this study, dynamic characteristics of the railroad roadbed which was constructed using crushed stones obtained from tunnel construction was investigated through the field investigation, real scale model test and numerical analysis. As a conclusion, the roadbeds built with the crushed stones produced at the tunneling site satisfy the requirement of roadbed in terms of displacement and earth pressure for the slab track in tile tunnel.

• Tuberculosis and Respiratory Diseases
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• 제73권3호
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• pp.143-150
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• 2012

Background: The release of interferon-gamma (IFN-${\gamma}$) by T lymphocytes increases after rechallenge with Mycobacterium tuberculosis antigen, especially, at a localized site of tuberculosis (TB) infection. We aimed to compare the clincial efficacy of two commercial IFN-${\gamma}$ release assays from pleural fluid for the diagnosis in tuberculous pleurisy. Methods: We performed T-SPOT.TB and QuantiFERON-TB Gold tests simultaneously on pleural fluid and peripheral blood samples from patients with pleural effusion, in South Korea, an area with intermediate TB burden. Results: Thirty-six patients were enrolled prospectively, and tuberculous pleurisy was found in 21 patients. Both the numbers of IFN-${\gamma}$ secreting T cells and the concentration of IFN-${\gamma}$ were greater in the pleural tuberculous group, comparing with the non-tuberculous group. Moreover, in the tuberculous group, there was a significant difference in IFN-${\gamma}$ producing spot-forming cells using the T-SPOT.TB method between pleural fluid and peripheral blood. The receiver operating characteristic (ROC) curve, was the greatest for pleural fluid T-SPOT.TB test, followed by peripheral blood T-SPOT.TB test, peripheral blood QuantiFERON-TB Gold test, and pleural fluid QuantiFERON-TB Gold test (area under the ROC curve of 0.956, 0.890, 0.743, and 0.721, respectively). The T-SPOT.TB assay produced less indeterminate results than did QuantiFERON-TB Gold assay in both pleural fluid and peripheral blood. Conclusion: These findings suggest that the pleural fluid T-SPOT.TB test could be the most useful test among the IFN-${\gamma}$ release assays for diagnosing tuberculous pleurisy in an area with an intermediate prevalence of TB infection.

• 항공우주시스템공학회지
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• 제12권2호
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• pp.30-36
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• 2018

본 연구에서는 무인복합형 회전익기 연구의 일환으로 축소형 Tip Jet 로터 시험장치를 개발하였으며, 이를 이용하여 Tip Jet 로터에 대한 성능 및 동특성 연구를 수행하였다. 축소로터는 시험장 여건 및 공압조건 등을 고려하여 2m급이 되도록 하였으며, 압축공기를 이용하여 구동된다. 축소로터의 회전속도는 압축공기의 압력을 이용하여 조절되며, 별도의 하중측정부를 두어 회전 시 발생하는 추력과 각 방향의 하중 데이터를 획득하게 된다. 동특성 시험을 위해 별도의 유압 가진기가 장착되어 있으며, 로터 가진 시 발생하는 블레이드의 flap, lag 및 torsion 방향에 대한 동적 응답을 확인하기 위해, 각 블레이드의 익근부에는 full-bridge strain gage를 부착하였다. 성능 및 동특성 시험은 로터 회전수 및 블레이드 피치각을 변경해가며 실시되었다. 아울러 시험 결과의 유효성을 확인하기 위해 CAMRAD II 해석 결과와 비교하였다.

• 한국지반환경공학회 논문집
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• 제21권1호
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• pp.5-12
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• 2020

지진원으로부터 전파되는 진동은 거리에 따른 감쇠와 지형 혹은 지질구조에 따라 지역마다 다른 증·감폭 특성을 가진다. 지진원에서 기반암까지의 전파되는 진동은 이격거리에 따른 감쇠의 영향이 크며, 이는 감쇠식을 통해 쉽게 추정할 수 있다. 하지만 지표면에 전달되는 진동 추정은 기반암 상부에 위치한 토층 고유주기의 영향을 받기에 위치별 지질정보 파악이 중요하다. 지질정보 기반 진도 추정을 위해 지반조사 자료가 필요하며, Vs 주상도가 없을 경우 표준관입시험을 통해 대상지반의 강도 및 특성 파악에 주로 사용된다. 국토지반정보 포털시스템에서는 국내 지반에서 수행된 지반조사자료를 통합하여 관리하고 있으며, 표준관입시험 정보가 약 40만공을 구축되어 있다. 본 연구에서는 지반정보를 기반으로 체감형 진도정보 산출을 위해 권역별로 증폭계수 정량화 가능성을 검토하였다. 이때 SPT-N치를 자료를 통해 전단파 주상도를 생성하고, 대상지역에 지반응답해석을 수행하였다. 권역별 증폭계수와 지진파의 주기별 진도 분포는 해석방법 및 권역설정에 따라 큰 차이를 보였다.