• Composites Research
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• 제20권2호
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• pp.21-26
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• 2007

이 논문은 합성섬유를 이용하여 포틀랜드 시멘트 모르타르를 보강한 복합재료인 ECC(Engineered Cementitious Composite)의 설계 과정과 건설현장에 이 복합재료를 적용할 수 있도록 시공성을 부여한 연구 내용을 정리하였다. 이 연구에서는 다양한 시공성, 즉 자기충전(self·consolidating)과 스프레이 시공성을 갖는 ECC를 제작하기 위하여 단계적인 재료 개발 방법론을 채택하였다. 우선 마이크로역학(micromechanics)과 안정상태균열이론(steady-state cracking theory)을 이용하여 골재와 섬유를 선정한 후, 굳기 전 재료의 레올로지를 제어하는 방법으로 시공성을 구현하였다. 여기서, 굳기 전 재료의 레올로지를 제어하기 위하여 화학첨가제(chemical admixtures)와 광물첨가재(mineral admixtures)의 양을 소량으로 조절하는 방법을 사용하였다. 이러한 방법을 활용함으로써 굳기 전에는 다양한 시공성을 나타내면서, 굳은 후에는 높은 연성(인장변형경화 거동)을 나타내는 실용적인 ECC 복합재료를 개발하였다.

• Journal of Periodontal and Implant Science
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• 제30권1호
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• pp.39-52
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• 2000

Polypeptide growth factor belong to a class of potent biologic mediator which regulate cell differentiation, proliferation, migration and metabolism. 1,25-dihydroxyvitamin $D_3$ decrease cell proliferation, and stimulate alkaline phosphatase activity which express in osteoblast during cell differentiation period. IGF-I is known to stimulate cell proliferation and differentiation too. 1,25-dihydroxyvitamin $D_3$ is known to increase IGF-I binding sites and IGF binding protein which inhibite the effect of IGF. The purpose of this study is to evaluate potential role of IGF-I as mediator that control the action of 1,25-dihydroxyvitamin $D_3$. MC3T3-E1 cell were seeded $5{\times}10^5/ml$ at 100mm culture plate in ${\alpha}-MEM$ containing 10% fetal bovine serum. After 48 hour incubation period, medium were changed ${\alpha}-MEM$ containing 5% fetal bovine serum. After 24 hours, $10^{-9}M$ 1,25-dihydroxyvitamin $D_3$ added. Total mRNA was extracted at 0, 6, 24, 48, 72 hour. PRPCR method was programed for the detection of IGF-I mRNA. In the both groups of 1,25-dihydroxy vitamin $D_3$ treated and control, alternative splicing form of IGF-I, IGF-IA and IGF-IB were expressed. In the 1,25-dihydroxyvitamin $D_3$ treated group, IGF-I mRNA expression was matained until 24 hour, there after expression was decresed. MC3T3-E1 cell were seeded $2.5{\times}10^4/ml$ at 24well plate in ${\alpha}-MEM$ containing 10% fetal bovine serum. After 48 hour incubation period, medium were changed ${\alpha}-MEM$ containing 3% fetal bovine serum. After 24 hours, $10^{-9}M$ 1,25-dihydroxyvitamin $D_3$ and 10 ng/ml IGF-I were added separately or together. Cell were cultured for 1 and 3 days, $2{\mu}Ci/ml\;[^3H]$ -thymidine was added for the last 24h of culture of each days. ${[^3H]}$-thymidine incorporation in to DNA was measured and expressed counter per minute(CPM). DNA synthetic activity was significantly decreased by 1,25-dihydroxyvitamin $D_3$ both at 1 day and 3 day, and in the combination group of 1,25-dihydroxyvitamin $D_3$ and IGF-I, DNA synthetic activity was also decreased both at 1 day and 3 days. IGF-I did not affect the DNA synthetic activity compared to control group both at 1 day and 3 day. From the above results, 1,25-dihydroxyvitamin $D_3$ was potent inhibitor of cell proliferaton in MC3T3-E1 cells. It assumed that the effect of 1,25-dihydroxyvitamin $D_3$ on osteoblast proliferation may be mediated in part by decreased level of IGF-I.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.376-379
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• 1996

Synthesis for qualitative analysis in connection with quantitative analysis from the pinch design method, EVOP and Operations Research is proposed for the optimal synthesis of heat exchanger networks, that is through of the transportation model of the linear programming for synthesizing chemical processing systems, to determine the location of pinch points, the stream matches and the corresponding heat flowrate exchanged at each match. In the second place, according to the optimization, the optimal design of heat transfer enhancement is carried on a fixed optimum heat exchanger network structure, in which this design determines optimal operational parameters and the chosen type of heat exchangers as well. Finally, the method of this paper is applied to the study of the optimal synthetic design of heat exchanger network of constant-decompress distillation plants.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.414-419
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• 2012

The evaluation of a zonal RANS-LES approach is documented for the prediction of broadband noise generated by the flow past unmodified and serrated airfoil trailing edges at a high Reynolds number. A multi-domain decomposition is considered, where the acoustic sources are resolved with a LES sub-domain embedded in the RANS domain. A stochastic vortex method is used to generate synthetic turbulent perturbations at the RANS-LES interface. The simulations are performed with a general-purpose unstructured control-volume code FLUENT. The far-field noise is calculated using the aeroacoustic analogy of Ffowcs Williams-Hawkings. The results of the simulation are validated through the full-scaled wind turbine acoustic measurements. It is found that the present approach is adequate for predicting noise radiation of serrated trailing edge flow for low noise rotor system.

• 한국소음진동공학회논문집
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• 제22권5호
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• pp.444-450
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• 2012

The evaluation of a zonal RANS-LES approach is documented for the prediction of broadband noise generated by the flow past unmodified and serrated airfoil trailing edges at a high Reynolds number. A multi-domain decomposition is considered, where the acoustic sources are resolved with a LES sub-domain embedded in the RANS domain. A stochastic vortex method is used to generate synthetic turbulent perturbations at the RANS-LES interface. The simulations are performed with a general-purpose unstructured control-volume code FLUENT. The far-field noise is calculated using the aeroacoustic analogy of Ffowcs Williams-Hawkings. The results of the simulation are validated through the full-scaled wind turbine acoustic measurements. It is found that the present approach is adequate for predicting noise radiation of serrated trailing edge flow for low noise rotor system.

• 말소리와 음성과학
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• 제10권4호
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• pp.121-125
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• 2018

This paper describes procedures of changing and measuring voice quality in terms of jitter. Jitter synthesis method was applied to the TD-PSOLA analysis system of the Praat software. The jitter component is synthesized based on a Gaussian random noise model. The TD-PSOLA re-synthesize process is used to synthesize the modified voice with artificial jitter. Various vocal jitter parameters are used to measure the change in quality caused by artificial systematic jitter change. Synthetic vowels, natural vowels and short sentences are used to check the change in voice quality through the synthesizer model. The results shows that the suggested method is useful for voice quality control in a limited way and can be used to alter the jitter component of voice.

• 대한임상검사과학회지
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• 제54권2호
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• pp.119-124
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• 2022

녹농균(Pseudomonas aeruginosa), 대장균(Escherichia coli) 및 포도알균(Staphylococcus aureus)은 기회감염균이다. 또한 이들 세균은 다제내성(Multiple-Drug Resistance, MDR) 세균의 성질을 가지는 것으로 알려져 있다. 녹농균, 대장균, 포도알균에 대한 다양한 효능을 지닌 6가지 발효액의 항균활성을 분석하였다. 발효액을 섭취했을 때 대장균에서 유전적 발현 변화가 일어나는지 알아보기 위해 annealing control primer를 사용하여 유전자발현 분석을 수행하였다. 디스크확산법을 통해 무화과식초와 대봉감식초가 다른 발효액에 비해 억제대의 크기가 가장 크게 나타났고, 토종약초발효소는 항균효과가 없었다. 대장균에 5% 무화과식초를 처리하여 21일간 매일 계대배양하여 Escherichia coli O157:H7 OmpW gene for outer membrane protein W 유전자 발현이 감소하며, Synthetic construct Lao1 gene for L-amino acid oxidase, complete cds 유전자가 발현이 증가함을 확인하였다. 발효액 중에서 특히 무화과식초를 섭취하는 것은 우리 주변에 항상 존재하는 대장균에 대해 방어능력을 더욱 단단하게 가질 수 있음을 의미하며, 나아가 다제내성균에 대한 천연치료제로 유용하게 쓰일 수 있기를 기대한다.

• 제어로봇시스템학회논문지
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• 제9권1호
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• pp.50-56
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• 2003

In electrical impedance tomography(EIT), various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. This paper presents a new combined method based on genetic algorithm(GA) and modified Newton-Raphson(mNR) algorithm via two-step approach for the solution of the static EIT inverse problem. In the first step, each mesh is classified into three mesh groups: target, background, and temporary groups. The mNR algorithm can be used to determine the region of group. In the second step, the values of these resistivities are determined using genetic algorithm. Computer simulations with the 32 channels synthetic data show that the spatial resolution of reconstructed images by the proposed scheme is improved compared to that of the mNR algorithm at the expense of increased computational burden.

• 항공우주시스템공학회지
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• 제11권1호
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• pp.1-7
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• 2017

위성은 임무수행을 위하여 발사체에 탑재되어 목표하는 궤도상에 도달하게 된다. 발사체의 비행동안 위성은 사인, 랜덤, 충격과 같은 극심한 발사 진동환경에 노출되게 되며, 이에 따라 위성체 내부에 위치한 전장품 및 전장품 기판에는 각 진동요소에 의한 발사 하중이 작용하게 된다. 발사하중 작용시, 전장품 내부에 장착된 기판은 체결부를 경계로 수직방향의 굽힘 거동을 주로 일으키게 되며, 이로 인한 상대변위로 기판 위 소자의 납땜부 파괴와 도선의 단선, 기판 자체의 균열을 초래한다. 성공적인 임무 수행을 위해서, 위성의 전장품 설계는 상기 현상들에 대해 기판의 구조 건전성 및 피뢰파괴 신뢰도가 확보되어야한다. 본 논문에서는 기존에 구조해석이 기 수행되었던 다목적실용위성 3호에 탑재되는 고해상도 위성카메라용 X-band 안테나 구동장치인 APD(Antenna Pointing Driver) 전장품의 제어 보드를 대상으로 하여, 스테인버그의 식을 통해 진동 하중에 의한 허용 처짐과 최대 처짐을 도출해내고, 팔머그렌 마이너 방정식을 이용하여 수명관점에서 피로파괴 예측의 유효성을 입증하였다.

• 한국세라믹학회지
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• 제44권6호
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• pp.325-330
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• 2007

High porous AlO(OH) gel is used in precursor of ceramic material, coating material and porous catalyst. For use of these, not only physiochemical control for particle morphology, pore characteristic and peptization but also studies of synthetic method for preparation of high porous AlO(OH) gel were required. In this study, high porous AlO(OH) gel was prepared through the aging and filtration process of aluminum hydroxides gel precipitated by the hydrolysis reaction of $Na_2CO_3$ solution and $Al_2(SO_4)_3$ and $Na_2SO_4$ mixed solution. In this process, optimum synthetic condition of AlO(OH) gel having excellent pore volume as studying the effect of hydrolysis pH on gel precipitates has been studied. Hydrolysis pH brought about numerous changes on crystal morphology, surface area, pore volume and pore size. Physiochemical properties of gel were investigated as using XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method.