• Food Industry And Nutrition
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• v.10 no.3
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• pp.5-9
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• 2005

비만은 제2형 당뇨병, 심혈관계 질환, 그리고 암을 비롯해 각종 질병의 위험인자로 작용한다. 비만은 낮은 수준의 전신성 염증상태로 간주되며, 비만시 증가하는 염증성 분자는 제2형 당뇨병 또는 동맥경화등의 비만성 질병 발생과정에 깊이 관여한다. 따라서, 염증제어는 비만성 질환제어를 위해 매우 중요하다. 지방세포 비대에 따른 지방세포 기능이상은 아디포사이토카인의 분비 이상을 초래하고, 비만성 질환의 발생 및 촉진자로 작용한다. 비만환자에게서의 MCP-1과 같은 염증성 아디포사이토카인의 분비 제어는 비만성 질환을 예방하거나, 또는 질병 발생 및 진행을 지연시키는 전략적 가치가 있을 것으로 사료된다. 지방세포가 분비하는 케모카인 가운데 MCP-1은 비대한 지방조직내로의 대식세포의 침윤 및 활성화를 유도하며, 특히 비대한 지방조직에서의 염증반응을 증폭시키는 역할을 한다. MCP-1은 내 장지 방조직에서 특히 그 분비량이 높았고, 따라서, 복부비만 관련 질환의 타겟분자로서 가치가 있을 것으로 생각된다. 또한, MCP-1 작용을 저해하는 항염증성 phytochemical은 비만으로 인한 염증성 질환의 발생을 지연시키거나, 즉 예방적인 차원에서 유용할 것으로 사료된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.543-547
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• 2015

The cooling process referred to as Tempcore has been applied to produce a high-strength rebar. Excellent rebar with strength and weldability can be manufactured from mild steel without the addition of alloying elements by using the Tempcore process. However, there are limitations to evaluating the effect of various chemical compositions and cooling conditions within a site facility. In this study, we developed an apparatus to simulate the Tempcore process and obtained microstructures with a hardened surface layer, an intermediate region and a soft inner core. The experimental apparatus has been equipped with a cooler set that is the same as the site facility and consists of a pump line that supplies pressure of 12-13 bar and flow rate of up to $50m^3/h$. In accordance with the simulation result of steel grade SD400 that requires more than 400 MPa of yield strength, both the hardened area ratio and the hardness with respect to each cooling depth were found to agree well with the product.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.349-354
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• 2023

This study wa s conducted a s pa rt of ma ximizing the use of ca rbon dioxide by a pplying CCU(Ca rbon Ca pture, Utiliza tion) a mong technologies for reducing CO₂ in the cement industry. In a carbon dioxide curing environment, changes in carbonation depth and changes in basic physical properties by age due to the mixing of carbonation reaction accelerators were usually targeted at Portland cement paste. In addition, in order to check the fixed amount of CO₂ in the concrete field, a thermal analysis method was applied to evaluate CaCO₃ decarbonization at high temperatures. As a result of the evaluation, it was confirmed that the carbonation depth in the cured body significantly increased due to the incorporation of CRA in the carbonation depth diffusion performance. In addition, it was confirmed that the weight reduction rate increased by 23.8 % and 40.77 %, respectively, compared to Plain, in the order of curing conditions for constant temperature and humidity and curing conditions for carbonation chambers, so it was confirmed that the amount of excellent CaCO₃ produced by the addition of CRA increased as the concentration of CO₂ increased.

• Computational Structural Engineering
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• v.5 no.1
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• pp.119-132
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• 1992

The objective of this study is to perform extensive parametric studies of the lateral-torsional buckling of short 1-beams under repeated loadings, and to gain a further insight into the lateral-torsional beam buckling problem. A one-dimensional geometrically (fully) nonlinear beam model is used, which includes superposed infinitesimal transverse warping deformation in addition to finite torsional warping deformation. A multiaxial cyclic plasticity model is also implemented to better represent cyclic metal plasticity in conjunction with a consistent return mapping algorithm. The general response for the lateral-torsional buckling of short I-beams under repeated loadings is examined through several parametric studies around the standard case : the material yield strength, the yield plateau, the strain hardening, the kinematic hardening, the residual stresses, the load eccentricity with respect to the shear center, the height of the load with respect to the cross-section of the beam, the location of the load along the length of the beam, the dimensions of the cross-section of the beam and the fixity of the supported end remote from the load.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.567-573
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• 2017

The drive shaft of passenger vehicle has an important role in transmitting the torque between the power train system and the wheels. Torsional fatigue failures occur generally in the connection parts of the spline edge of the drive shaft, when there is significant fatigue damage under repeated twisting loads. A heat treatment, an induction hardening process, has been adopted to increase the torsional strength as well as the fatigue life of the drive shaft. However, it is still unclear how the extension of the induction hardening process in a used material relates to its shear-strain fatigue life range. In this study, a shear-strain controlled torsional-fatigue test with a specially designed specimen was conducted by an electro-dynamic torsional fatigue test machine. A finite element analysis of the drive shaft was carried out using the results obtained by the fatigue experiment. The estimated fatigue life was verified through a twisting load test of the real drive shaft in a test rig.

• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.94-103
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• 2023

The effects of carburizing pressure and gas ratio on vacuum carburizing properties (uniformity and surface characteristics) have been studied through the analyses of carbon concentration, hardness, surface color, surface roughness and type of carbon bonding. AISI 4115 steel specimens were carburized with various pressures (1, 5, and 10 Torr) at different locations (P₁, P₂, P₃, P₄, P₅, and P₆) inside a furnace held at 950 ℃. Since the carburizing pressure represents the density of the carburizing gas, it plays an important role in improving the carburizing uniformity according to locations in the furnace. As the carburizing pressure increased, the carburizing uniformity according to the sample location was improved, but the surface of the carburized specimen was discolored due to the residual acetylene gas, which does not contribute to the carburizing reaction. Therefore, the carburizing uniformity and surface discoloration have been improved by injecting acetylene gas (carburizing gas) and nitrogen gas (non-reactive gas) in a specific ratio.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.139-148
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• 2004

MMPs(Matrix metalloproteinases)는 치주질환에서 주된 조직파괴단백분해효소인 것은 알려져 있고 TIMPs(Tissue inhibitor of Matrix metalloproteinase)는 MMPs의 작용을 억제한다라고 알려져 있다. 이 둘간의 불균형으로 인해서 조직파괴가 더 가속화될 수 있다. 이 두 연구의 목적은 ELISA kit를 사용하여 특정 MMPs(1,2,3,8,9,13)과 TIMPs(1,2)의 양이 건강한 환자와 비교하여서 치주염 환자에서 달라지는지 알아보고 MMPs(1,2,3,8,9,13), TIMPs(1,2)와 치은열구깊이와 GI score와의 관계를 알아보기로 한다. 8명의 만성 치주염 환자와 4명의 급속진행형 치주염 환자가 실험군으로 참여하였고 5명의 건강한 치주조직을 환자가 대조군으로 참여하였다. 임상적인 측정은 GI score와 치주낭측정을 통하여 이루어졌다. 8명의 만성 치주염을 가진 환자와 4명의 급속진행형 치주염을 가진 환자에서 각각 치주낭 깊이가 3mm이하인 부위에서 6개의 치은열구액 표본과 치주낭 깊이가 6mm 이상인 곳에서 6개의 치은열구액 표본을 채취하였다. 건강한 치주조직을 가진 5명의 환자는 단지 치주낭깊이가 3mm 이하인 건강한 부위에서만 치은열구액 표본을 제공하였다. MMPs(1,2,3,8,9,13)과 MIMPs(1,2)의 측정은 Human Biotrack ELISA kit를 사용하여서 측정하였다. 통계처리는 MMPs, MIMPs의 실험군과 대조군의 차이는 Kruskal-Wallis test를 사용하였고 MMPs, TIMPs와 치주낭 깊이와 GI score의 관계정도는 Pearson's correlation coefficient를 사용하였다. 실험결과 대조군과 비교하여 만성 치주염 환자에서 치주낭 깊이가 6mm 이상인 부위에서 MMP9의 수치가 통계적으로 유의할만하게 높았으며(p=0.04) MIMP2의 수치가 대조군과 비교하여 치주낭 깊이가 3mm 이하인 부위를 가진 만성치주염 환자에서 통계적으로 유의할만하게 높았다(=0.049). MMPs(1,2,3,8,9,13), MIMPs(1,2)의 활동성과 치주낭 깊이의 관계에서 둘간의 통계적으로 유의할만한 관계는 존재하지 않았으나 MMP1(r=0.35)과 MMP2(r=0.31)가 상대적으로 높은 관계를 보였다. 또한 MMPs(1,2,3,8,9,13), MIMPs(1,2)의 활동성과 GI score의 관계에서도 둘간의 통계학적으로 유의할만한 관계는 존재하지 않으나 MMP1(r=0.4), MMP2(r=0.29), MMP9(r=0.26)가 상대적으로 높은 관계를 보였다. 이 실험의 결과로 볼 때 MMP9가 만성치주염 환자의 질환이 있는 부위에서만 염증의 지표가 될 수 있으며 MIMP2가 만성치주염 환자의 염증이 없는 부위에서 높은 농도로 존재하는 것으로 보아서 MIMP2가 MMPs에 대한 억제작용을 하여서 염증의 진행을 방해하는 역할을 한다라고 볼 수 있다.

• The Journal of the Acoustical Society of Korea
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• v.33 no.5
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• pp.300-308
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• 2014

Photoacoustic imaging is a useful tool for the diagnosis of atherosclerosis because it is capable of providing anatomical and pathological information at the same time. A photoacoustic signal detector is a pivotal element to achieve high spatial resolution, so that it should have broadband spectrum with a high center frequency. Since a photoacoustic imaging probe is directly inserted into blood vessel to diagnose atherosclerosis, the total size of the photoacoustic signal detector should be less than 1 mm. The main purpose of this paper is to demonstrate that PVDF can be used as an active material for the photoacoustic signal detector with a high frequency and broadband characteristic. The photoacoustic signal detector developed in this study was a single element ultrasound transducer with an aperture of $0.5{\times}0.5mm$ and the total size of 1 mm. In the design stage, the natural focal depth was adjusted for an effective focal area to cover the region of interest, i.e., 1~5 mm in depth. This was because geometrical focusing could not be used due to the small aperture. Through a pulse-echo test, it was ascertained that the developed photoacoustic signal detector has the -6 dB bandwidth ranging between 40.1 and 112.8 MHz and the center frequency of 76.83 MHz.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.57-64
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• 2006

The crack presented in concrete structures causes a structural defect, the durability decrease, and external damages etc. Therefore, it is necessary to improve durability through the effort to control the crack. Fluosilicic acid($H_2SiF_6$) is recovered as aqueous solution which absorbs $SiF_4$ produced from the manufacturing of industrial-graded $H_3PO_4$ or HF. Generally, fluosilicates prepared by the reaction between $H_2SiF_6$ and metal salts. Addition of fluosilicates to cement endows odd properties through unique chemical reaction with the fresh and hardened cement. Mix proportions for experiment were modulated at 0.45 of water to cement ratio and $0.0{\sim}2.0%$ of adding ratio of fluosilicate salt based inorganic compound. To evaluate correlation of concrete strength and adding ratio of fluosilicate salt based inorganic compound, the tests were performed about design strength(21, 24, 27 MPa) with 0.5% of adding ratio of fluosilicate salt based inorganic compound. Applications of fluosilicate salt based inorganic compound to reduce cracks resulted from plastic and drying shrinkage, to improve durability are presented in this paper. Durability was evaluated as neutralization, chloride ion penetration depth, freezing thawing resistant tests and weight loss according reinforcement corrosion. It is ascertained that the concrete added fluosilicate salt based inorganic compound showed m ability to reduce the total area and maximum crack width significantly as compared non-added concrete. In addition, the durability of concrete improved because of resistance to crack and watertightness by packing role of fluosilicate salt based inorganic compound obtained and pozzolanic reaction of soluble $SiO_2$ than non-added concrete.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.741-750
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• 2004

Air voids in hardened concrete have an important influence on concrete durability such as freeze-thaw resistance, surface scaling resistance, and water permeability, and they have been characterized by spacing factor Linear traverse and point count methods in ASTM standard have been used in estimating an air void system in hardened concrete. However, these methods require lots of time and efforts, further they are not repeatable. Image analysis method could be utilized In estimating an air void systems in hardened concrete with a developments of microscope, digital camera and computer program. The purpose of this study was to develope image analysis method and provide a guideline by comparing the results from ASTM method and image analysis method. The concerns were at air void content and diameter distribution, air voids system as well as spacing factors. The experimental variables included air content by air entrained agent (0, 0.01, $0.03\%$) and depth of specimen (top, middle, bottom). The result showed that it was possible to calculate spacing factor using image analysis technique, as well as air content, air diameter distribution, and air structure. This study also contributed in developing an reasonable and repeatable image analysis method.