• Applied Chemistry for Engineering
• /
• v.9 no.6
• /
• pp.798-802
• /
• 1998

Carbon granules were prepared by granulating a mixture of coconut shell powder and coal tar solution, and then by carbonizing at different temperatures. To control micropores of the carbonized granules, the deposition time of benzene vapor under nitrogen atmosphere was varied. For each prepared sample, SEM morphology and true density were investigated. The adsorption rates on the granules were measured with respect to oxygen and nitrogen by means of the Cahn D-200 system. Diffusivity, selectivity and amount of equilibrium adsorption for the gases were obtained from the measurement of adsorption rate. Based on the analysis of the adsorption characteristics, the optimum temperature and the deposition time for preparation of the molecular sieve carbon granules were found to be $800^{\circ}C$ and 10 minutes, respectively. At these optimal conditions, the selectivity coefficient, 26.4, 0f oxygen and nitrogen was obtained.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1085-1090
• /
• 2011

To assure the safety of rolling stock, it is important to perform the fatigue analysis of reduction gear unit in rolling stock considering a variation of velocity and traction motor capability. This paper presents fatigue analysis of the damage of reduction gear unit of railway vehicle under variable amplitude loading(VAL) based on quasi-static fatigue analysis using finite element model and linear Miner's rule. The VAL for the simulation was constructed from the tractive effort curve and train run curves of railway vehicle under commercial operation condition using MSC.ADAMS dynamic analysis. The finite element model for evaluating the carburizing effect on the gear surface was used for predicting the fatigue life of the middle gear based on strain-life based approach. The results showed that the frequent high starting torque due to a quick start as well as increasing numbers of stops at station would decrease the fatigue life of reduction gear unit.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.5
• /
• pp.805-811
• /
• 2018

Recently, Format-Preserving-Encryption (FEA) was suggested by the National Security Research institute (NSR) as an encryption method while maintaining the format without a distortion to the intended information to be encrypted. In this paper, we propose a scheme to solve conventional cyber security problems by using FEA scheme. First, we present the method to encrypt signatures and extensions with FEA in order to effectively defend against Ransomeware attacks. This technique can mitigate the exposure to the Ransomeware by encrypting the minimum information. Second, in order to reduce the secret information for Steganography, we introduce a new way to minimize the secret information with FEA. Finally, we compare the operation speed by encryption with FEA and Lightweight Encryption Algorithm (LEA), furthermore when we optimize FEA we want to compare with the performance improvement accompanying with it.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.1
• /
• pp.29-36
• /
• 2008

In this paper, the orbital forming analysis of an automotive hub bearing was studied to predict forming performances using the explicit finite element method. To find an efficient solution technique for the orbital forming, axisymmetric finite element models and 3D solid element models were solved and numerically compared. The time scaling and mass scaling techniques were introduced to reduce the excessive computational time caused by small element size in case of the explicit finite element method. It was found from the numerical simulations on the orbital forming that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations at the inner race of bearing were quite different. Finally the strains at the inner race of bearing and the forming forces to the peen were measured for the same product of the numerical model by test, and were compared with the 3D solid element results. It was founded that the test results were in good agreements with the numerical ones.

• Geophysics and Geophysical Exploration
• /
• v.18 no.3
• /
• pp.133-142
• /
• 2015

Displacement of the Earth's surface due to atmospheric loading has been recognized since a century years ago, and its accurate estimation is required in present day geodesy and surveying, particularly in space geodesy. Atmospheric load deformation in continental region can readily be calculated with the given atmospheric pressure field and the load Green's function, and, in near coastal area, approximate model is used for the calculation. The changes in the Earth's atmospheric circulation and the seasonal variation of atmospheric pressure on two hemispheres of the Earth are the each main causes of variation of the Earth's spin angular velocity and polar motion respectively. Wind and atmospheric pressure do the major role in other periodic and non-periodic perturbations of the positions in the Earth's reference frame and variations in the Earth's spin rotational state. In this reviewing study, the developments of related theories and models are summarized along with brief description of phenomena, and the geodetic perturbing effects of a hypothetical typhoon passing Korea are shown as an example. Finally related existing problems and further necessary studies are discussed in general.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.5
• /
• pp.157-170
• /
• 1999

A new design technique is presented to stabilize cut slopes in cohesive soils by use of piles. The design method can consider systematically factors such as the gradient and height of slope, the number and position of pile's rows, the interval and stiffness of piles, etc. The design method is established on the basis of the stability analysis of slope with rows of piles. The basic concept applied in the stability analysis is that the soil across the open space between piles can be retained by the arching action of the soil, when a row of piles is installed in soil undergoing lateral movement such as landslides. To obtain the whole stability of slope containing piles, two kinds of analyses for the pile-stability and the slope- stability must be performed simultaneously. An instrumentation system has been installed at a cut slope in cohesive soil, which has been designed according to the presented design process. The behavior of both the piles and the soil across the open space between piles is observed precisely. The result of instrumentation shows that the cut slope has been stabilized by the contribution of stabilizing effect of piles on the slope stability in cohesive soil.

• Journal of IKEEE
• /
• v.2 no.2 s.3
• /
• pp.239-246
• /
• 1998

In this paper, a new morphological details extraction algorithm is proposed. It is known that separate transmission of details and background smoothed image is a powerful technique for very low bit-rate video data transmission. Several details extraction algorithms show relatively large variation of grayscale levels in details, smoothed image, which is the difference between original and details images, provides highly distortedand complicated result. In order to remedy those pitfails, and thus to improve the coding efficiency, we propose a new algorithm using the reconstruction top-hat result as the reference image in process of obtaining details, instead of top-hat result, which is used fur existing a1gorithms. Experimental results show that details, extracted using the proposed algorithm, are much similar to original image, and thus the smoothed image is not too complicated.

• Journal of Broadcast Engineering
• /
• v.15 no.3
• /
• pp.332-345
• /
• 2010

A unified image enhancement method is proposed for high-resolution image which based on color constancy and histogram equalization using edge region. To speed up the method, smaller image is used when parameters of color constancy and histogram equalization are determined. In the color constancy process, nth-derivative of gaussian is applied to x and y axis separately in order to estimate the color of the illumination rapidly. In the histogram equalization process, the histogram obtained from near-edge region is used for the histogram equalization. In the experiments, high-resolution images taken by digital camcorder are used for verifying the performance of the proposed method.

• Journal of Broadcast Engineering
• /
• v.15 no.3
• /
• pp.368-379
• /
• 2010

As high-definition video is broadly used in various system such as broadcast system and digital camcorder the proper method in order to improve the quality of high-definition video is needed. In this paper, we propose an efficient method to improve color and contrast of high-definition video. In order to apply the image enhancement method to high-definition video, scale-down video of high-definition video is used and the parameter for image enhancement method is computed from small size video. To enhance the color of high-definition video, we apply color constancy method. First, we separate the video into several scenes by cut detection method. Then, we apply color constancy to each scene with same parameter. To improve the contrast of high-definition video, we use union of original image and histogram equalized image, and weight is calculated based on sorting of histogram bins. Finally, the performance of proposed method is demonstrated in experiment section.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 1994.07a
• /
• pp.7-8
• /
• 1994

한국산 표고버섯 균사체를 액체배양하여 천연항암물질로 알려진 단백다당체를 추출한 후 그 물질의 특성에 대하여 검토하였다. 균사체의 최적 재양조건을 TGY배지로 조사한 바 온도 $25^{\circ}C$, 배양초기 pH4.0, 교반속도 300rpm, 균사배지 접종량을 10.0%로 하고 산소 통기량을 1.0volume of ait/volume of medium/mimute으로 하였을때 가장 양호한 조건이였으며, 대량생산 하기 위한 SCM배지에서 최적의 C/N비는 13.1오써 7일간 배양하였을때 18.8g/L의 균사령을 얻었으며, 이때 생산수율은 0.46으로 나타났다. 발효가 끝난 배양액에서 균사, 여액 그리고 배양액의 전체에서 단백다당체를 분리한 결과 각 분획에서 단백다당체가 각각 0.55%, 0.12%, 0.69%가 회수되어 배양액 전체에서 단백다당체를 추출하는 것이 바람직하며, 추출방법으로 열수추출, glass bead추출 및 cellulasa처리를 하여 단백다당체의 수율을 비교한 결과 0.25-0.5mm glass nead로 30분간 균사체를 분쇄한 다음 열수추출을 1시간을 하였을때 990mg/100ml의 단백다당체를 얻을 수 있었다. 고단백다당체를 1차 단백질 가수분해 효소로 분해하고, EDAE cellulose 및 Sepadex G-100 column chromatography로 정제한 후, TLC/FLD, ultracentrifugation한 결과 순수한 물질임을 알 수 있었다. 단백다당체의 항암효과 조사중 in vitro배양에서 $P_{388}$과 $L_{1210}$에 대한 단백다당체의 활성단위 1 unit는 1mg정도였으며, 인체의 장암세포인 HCT-48, HRT-18, HT-29 밀 간암세포인 Hep G2 대한 생육저해 단위는 각각 4.4, 3.6, 6.6, 2.6mg이었다. HCT-48과 Hep G2 세포의 크기 분포도는 대조군에 비하여 시간이 경과함에 따라, 그리고 단백다당체의 농도가 증가함에 따라 peak가 작은 size 쪽으로 이동하였다. 또, 단백다당체를 첨가 배양한 HCT-48과 Hep G2세포의 현미경 관찰에서 본래의 암세포 형태가 변형되고 크기가 감소하며 세포사이의 경계막이 흐트러지면서 세포수가 감소하고 사멸하였다. In vivo실험에서는 대조군보다 단백다당체를 첨가한 군에서 항체 형성능력이 대조군에 비하여 형질세포가 2배로 증가하였다. 단백다당체의 화학적 성분 분석에서 다당함량은 46.1%이면 구성다당류는 glucose, galactose, mannose, xylose로 구성되었고 단백질의 함량은 7.28%이며, 구성아미노산은 15종의 아미노산으로 되었다. 또 무기물은 Na, K, Zn, Ca등의 순으로 이루어 짐을 알 수 있었다.