Nondestructive Characterization of Metal Matrix Composite by Means of Ultrasonics

한근조,이준현 東亞大學校 海洋資源硏究所 1993 硏究論文集 Vol.6 No.1

초음파를 이용하여 비파괴적으로 단섬유 강화 알루미늄복합재료의 탄성계수의 측정기법에 대하여 연구하였다. 이를 위해 강화섬유 함유량을 0%에서 30%까지 5단계로 변화시킨 시험편을 제조하여 강화재 체적율의 변화에 따른 탄성계수의 변화를 정량적으로 측정하여 종래의 파괴적인 방법으로 구한 결과와 비교 검토 하였다. 그 결과 초음파의 종파, 횡파속도로 부터 비파괴적으로 평가된 탄성계수의 값은 4점굽힘시험에 의해 파괴적으로 측정된 값에 비교해 약간 낮은 값을 보이고 있으며, 등가응력조건(equal stress condition) 식에서 구한 이론적인 결과와 잘 일치하고 있음을 보여주고 있다.

쐐기형 레일클램프의 초기압착력 발휘를 위한 중추무게에 관한 연구

한근조,한동섭 東亞大學校 2005 東亞論叢 Vol.42 No.-

The wedge type rail clamp has the operating mechanism: First, the jaw pad clamps a rail with small clamping force. Next as the wind speed increases, the clamping force of the jaw pad is increased by the wedge. In order to design the wedge type rail clamp, we need to determine the proper wedge angle to minimize the sliding distance of a roller and the proper clamping angle of a locker to generate the initial clamping force of a jaw pad. The researches for the proper wedge angle have conducted, and in this study we conducted the investigation to determine the proper clamping angle of a locker in the rail clamp with wedge angle of 10˚. Because the initial clamping force of the jaw pad was determined by the clamping angle of the locker, in order to carry out the clamping force of a jaw pad, we measured the locking force applied to a locker with respect to the clamping angle of a locker, such as 3°, 4°, 5°, 6° using a pressure gauge, and compared the results with the FEA results.

기계실 위치 변화가 고효율 갠트리 크레인의 안정성에 미치는 영향 분석

한근조,이성욱 東亞大學校 2005 東亞論叢 Vol.42 No.-

This study was carried out to analyze the effect of machinery house loaction on the stability of high efficiency gantry crane which can improve the productivity of the container transportation work by reducing cycle time. The wind load was evaluated according to 'Load Criteria of Building Structures' enacted by the ministry of construction & transportation. The uplift forces of high efficiency gantry crane under this wind load were calculated by analyzing reaction forces at each supporting point. And variation of reaction forces at each supporting point was analyzed according to machinery house location.

쐐기형 레일클램프에서 조의 회전을 방지하기 위한 적정 쐐기각에 대한 연구

한동섭,한근조,심재준,이성욱 東亞大學校 大學院 2005 大學院論文集 Vol.30 No.-

Recently many countries have concentrated their effort on the port automation, in order to be the Hub-port, that the ULCS (Ultra Large Container Ship) could come alongside the quay in their region. As the magnitude of the container ship increases, that of the container crane (used in quay) increases from 50ton-class to 61ton-class more and more. The wind velocity criteria to design the structures used in the port was upgraded from 30m/s to 40m/s due to change of the weather condition. When we design wedge type rail clamp which can protect container crane from sudden wind blast with constant clamping force regardless of the operating period, it is important to determine the angle of wedge within proper range. In this study we designed the wedge angle of the wedge-type rail clamp using the FEA.

A Study on the Comparison of wind pressure on the member of Container Crane using Wind tunnel test and CFD

한근조,안태원,이성욱,한동섭 동아대학교 생산기술연구소 2006 生産技術硏究所硏究論文集 Vol.11 No.-

Because strong wind is one of the few forces that, although considered in container crane design, still cause significant damage, a container crane was tested to investigate wind load characteristic in uniform flows. So, this study measured an external point pressure at the each members of a container crane according to a wind direction and a shape of members in a wind-tunnel test. The result of this test was compared to those of computation fluid dynamics using a CFX 10. The scale of a container crane model for wind tunnel test applied similarity scales to consider the size of the wind tunnel test section and the boundary condition for CFD is like wind tunnel test.

Energy Method와 幾何學的 方法에 의한 圓環의 垂直, 水平 變位比較

韓根祚 동아대학교 공과대학 부설 한국자원개발연구소 1985 硏究報告 Vol.9 No.1

To study the elastic behavior of thick ring under the concentrated compression load, the geometric method by the circumferential deformation and the angular displacement and energy method-Castigliano's theorem-were adopted. The influence of diameter, thickness and ratio t/D was researched and the comparison of the two theories were followed up by the experimental results. The results obtained are as follows. 1. P/Δ by either geometric method or energy method are exclusively determined by the ratio t/D, nether t nor D 2. In the vertical deformation P/Δ₃is smaller than P/Δ₁ and the experimental results P/Δ_(e) have almost linear trends and approach to P/Δ₃ more closely, and in the horizontal deformation, P/Δ'_(e) approaches to P/Δ'₂ 3. In the vertical deformation, the absolute value P/Δ₁ and the approximate value P/Δ₂ don't show great difference, but in the horizontal deformation, they do. At most, P/Δ' is larger than P/Δ.

서울시 지하철 역사내 라돈의 농도분포

황인조,한근혁,최형욱,김동술,김신도 경희대학교 환경연구소 2001 環境硏究 論文集 Vol.10 No.-

The various existing situations like overpopulation, urbanization, industrialization, and heavy traffic volume in the Seoul metropolitan area have led to the air pollution problem, traffic problem, and increase in opportunities of residing underground place. So, recently in Korea, the residents using underground working place have been of great concerns on indoor air pollutants such as HCHO, radon, particulate matter, carbon monoxide. However, the studies on indoor air pollution have been not extensively conducted in Korea. Indoor radon is an odorless, colorless, tasteless, invisible, inert, and naturally occurring radioactive gas. And it has been known as one of the notorious carcinogens. The purpose of this study was to survey the concentration variations of radon in the subway stations located Seoul metropolitan area. Total of 216 subway stations were surveyed by the continuous radon monitors from Mar. 2001 to Jun. 2001. The study showed that average radon levels of concourses in each line were 1.51, 1.45, 1.51, 1.23, 1.28, 1.37, 1.12, 1.28 pCi/L and those of platforms in each line were 2.09, 1.43, 1.37, 1.67, 1.44, 1.54, 1.40, 1.22 pCi/L, respectively. The study results showed that the average radon concentrations were 1.19 pCi/L in outdoor, 1.34 pCi/L in concourse, and 1.52 pCi/L in platform, respectively.

高溫低싸이클 疲勞크랙전파에 미치는 過度的 크리이프變形擧動의 影響

周原植,韓根祚 동아대학교 공과대학 부설 한국자원개발연구소 1985 硏究報告 Vol.9 No.1

Considering the elastic strain and the creep strain at high temperature low cycle fatigue, together, we could find that the experimental modified J integral, J'ex is larger than the theoretical value, J'a. To investigate which effects this enlargement have on the crack propagation in the creep-fatigue interaction range, the high temperature low cycle fatigue crack experiment was accomplished using CN specimens. The results are as follows. 1. The enlargement of J'ex is not considerable at R=0 but at R=-1 it is considerable. 2. J'ex with low stress holding time is 2-10 times larger than the one without holding time. 3. In case of no holding time, the enlargement of J'ex has effects on the crack crack propagation rate at R=-1, but at R=0 a certain factor having no effects was found out.

高溫疲勞에서 싸이클依存型 및 時間依存型 疲勞크랙傳播의 遷移 : 싸인應力波 및 사디리꼴應力波에 대하여

成洛元,周原植,韓根祚 東亞大學校 大學院 1984 大學院論文集 Vol.8 No.2

A study on the nonlinear fracture mechanics was made on the low-cycle fatigue crack growth in SUS304 stainless steel under trapezoidal and sine stress wave at 650℃. The high temperature low cycle fatique crack growth behavior was classified into two categories: cycle-dependent and time dependent. The cycle-dependent crack growth rate correlated well with J integral range ?J, whereas the time dependent crack growth rate was characterized by modified J integral Jex. A parameter βwas found useful in predicting the transition from the cycle-dependent crack growth to the time-dependent crack growth. Conducting the experiment of high temperature fatigue crack propagation in trapezoidal, and sine stress wave, following conclusions were obtained. 1. Crack propagation behavior can be classified into cycle-dependent and time-dependent. 2. The transition of cycle-dependent crack propagation to time dependent one could be predicted bt either parameter βor ?J/ ?J?.

Spiral Spring Constant의 卷數 및 角變位에 따른 變化

全彦燦,周元植,韓根祚 東亞大學校 大學院 1984 大學院論文集 Vol.8 No.2

Spiral Spring Constant does not vary when the number of spiral is infinite, which can be shown by energy method, opplied to the deformed body. In usual cases, the number of spiral is infinite and the spring constant varies according to the initial number of spiral and acting torque. This paper is focused on the numerical analysis of the deviation tendency in two cases, fixed end and hinged end. The results are as follows. 1. The scales of gauges using spiral spring should be compensated according to the result of analysis. 2. The absolute values of r₁are smaller than the ones of r and in order to limit the deviation within 0.1%, N should be equal to or larger than 6 in the fixed end case and N should be equal to or larger than 4 in the hinged end case. 3. Dividing N by 0.25 step, e.g. 4, 4.25, 4.50, 4.75, r is smallest when N=integer + 0.75 and r₁is when N=integer.