• 한국연소학회지
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• 제13권1호
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• pp.17-22
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• 2008

A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.

• Smart Structures and Systems
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• 제15권5호
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• pp.1293-1309
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• 2015

3D two adjacent buildings with different heights founded in different kinds of soil connected with viscous dampers groups, with especial arrangement in plane, were investigated. Soil structure interaction for three different kinds of soil (stiff, medium and soft) were modeled as 3D Winkler model to give the realistic behavior of adjacent buildings connected with viscous dampers under various earthquake excitations taking in the account the effect of different kinds of soil beneath the buildings, using SAP2000n to model the whole system. A range of soil properties and soil damping characteristics are chosen which gives broad picture of connected structures system behavior resulted from the influence soil-structure interaction. Its conclusion that the response of connected structures system founded on soft soil are more critical than those founded on stiff soil. The behavior of connected structures is different from those with fixed base bigger by nearly 20%, and the efficiency of viscous dampers connecting the two adjacent buildings is reduced by nearly 25% less than those founded on stiff soil.

• 한국재료학회지
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• 제17권2호
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• pp.121-123
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• 2007

Energy harvesting from the vibration through the piezoelectric effect has been studied for powering the wireless sensor node. As piezoelectric unimorph cantilever structure can transfer low vibration to large displacement, this structure was commonly deployed to harvest electric energy from vibrations. Piezoelectric unimorph structure was composed of small stiff piezoelectric ceramic on the large flexible substrate. As there is the large Young's modulus difference between the flexible substrate and stiff piezoelectric ceramic, flexible substrate could not homogeneously transfer the vibration to stiff piezoelectric ceramic. As a result, most piezoelectric ceramics had been broken at the certain point. We measured and analyzed the stress distribution on the piezoelectric ceramic on the cantilever.

• Kyungpook Mathematical Journal
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• 제51권4호
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• pp.435-456
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• 2011

The Chebyshev collocation method in [21] to solve stiff initial-value problems is generalized by using arbitrary degrees of interpolation polynomials and arbitrary collocation points. The convergence of this generalized Chebyshev collocation method is shown to be independent of the chosen collocation points. It is observed how the stability region does depend on collocation points. In particular, A-stability is shown by taking the mid points of nodes as collocation points.

• Earthquakes and Structures
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• 제1권2호
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• pp.163-175
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• 2010

The vertical axis through the modal center of rigidity (m-CR) is used for interpreting the code torsional provisions in the design of eccentric multi-story building structures. The concept of m-CR has been demonstrated by the author in an earlier paper and the particular feature of this point is that when the vertical line of the centers of mass at the floor levels is passing through m-CR, minimum base torsion is developed. For this reason the aforesaid axis is used as reference axis for implementing the code provisions required by the equivalent static analysis. The study examines uniform mixed-bent-type multistory buildings with simple eccentricity, ranging from torsionally stiff to torsionally flexible systems. Using the results of a dynamic response spectrum analysis as a basis for comparisons, it is shown that the results of the code static design are on the safe side in torsionally stiff buildings, but unable to predict the required strength of bents on the stiff side of systems with a predominantly torsional response. Suggestions are made for improving the code provisions in such cases.

• 콘크리트학회논문집
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• 제23권4호
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• pp.511-520
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• 2011

최근 국내에서는 고분자 화합물인 폴리우레아를 이용하여 보강 성능의 향상을 위한 연질형 폴리우레아를 개발하여 구조물에 적용하였지만 보강 성능은 미비한 것으로 나타났다. 따라서, 이 연구에서는 폴리우레아를 구조물의 보강재로 사용하기 위하여 연질형 폴리우레아의 구성 요소를 변화시켜 경질형 폴리우레아를 개발하였다. 개발된 경질형 폴리우레아는 연질형 폴리우레아에 비해 경도와 인장강도가 향상된 성능을 나타내었다. 경질형 폴리우레아를 일반 구조물의 보강재로 사용하기 위하여 RC 슬래브 시험체를 제작하여 보강 성능을 평가하였으며, 현재 보강재로 사용되는 섬유 시트와 적층하여 보강한 후 성능을 평가하였다. 실험 결과 경질형 폴리우레아만으로 보강한 시험체가 무보강 시험체보다 우수한 강성 증진 효과와 연성 증진 효과를 나타내는 것으로 나타났다. 또한, 섬유 시트를 부착한 후 경질형 폴리우레아를 외부에 도포하여 보강한 시험체는 섬유 시트만으로 보강한 시험체보다 보강 성능이 매우 우수한 것으로 나타났다. 그러나 경질형 폴리우레아를 도포한 후 섬유 시트를 부착한 시험체는 경질형 폴리우레아의 변형을 강성이 높은 섬유 시트가 억제하여 하중이 가해지며 생기는 응력이 한곳에 집중되어 취성적인 파괴 거동을 보이는 것으로 나타났다.

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 1999년도 학술대회
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• pp.38-40
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• 1999

$\cdot$ Arthroscopic management is the effective method with acceptable results for coronoid impingement of stiff elbow contributing to the functional improvement and pain relief. $\cdot$ The functional improvement and pain relief seem to be affected by the severity of a degenerative change of the elbow joint. $\cdot$ Excision of coronoid process is required in a marked limitation of further flexion in addition to deeping of the coronoid fossa and anterior capsular release. $\cdot$ Excision of olecranon tip or posterior capsular release are effective method in severe flexion contracture.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1831-1835
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• 2014

Background: To investigate the relationship between extracellular matrix parameters and texture of prostatic lesions evaluated by transrectal real-time tissue elastography (TRTE). Methods: 120 patients suspicious for prostate cancer underwent TRTE. Targeted biopsies were carried out after 12-core systematic biopsy. Epithelia were stained with hematoxylin-eosin, and Victoria blue and Ponceau S were used to stain elastic-collagen fibers, and picric acid-sirius red for visualization of collagen type I (Col1) and III (Col3). Smooth muscles were visualized by immunohistochemistry. All image analyses were performed in a blind manner using Image Pro Plus 6.0, and the area ratios of epithelium, elastic fibers, collagen fibers and Col1/Col3 were determined. Results: 42 patients with typical elastograms were included in the final data analysis. Significant differences were detected between the benign and malignant groups in the area ratios of epithelium (P = 0.01), smooth muscles and Col1/Col3 (P = 0.04, P = 0.02, respectively). There were no significant differences in the area ratios of epithelium, smooth muscle and elastic fibers between the stiff and soft lesion groups. The area ratio of Col1 was ($0.05{\pm}0.03$) in the stiff group, and ($0.02{\pm}0.01$) in the soft group (P= 0.00). However, the area ratio of Col3 was ($0.03{\pm}0.02$) in the stiff group, and ($0.05{\pm}0.04$) in the soft group (P = 0.16). Col1/Col3 in the stiff group ($1.99{\pm}1.59$) was greater than in the soft group ($0.71{\pm}0.64$) (P = 0.01). Conclusions: Tissue hardness of prostatic tumors was mainly dependent on the Col1 content, Col1/Col3 being higher in malignant than in benign lesions, so the prostate tissue texture can be used as a target for distinguishing between the two with TRTE.

• Clinics in Shoulder and Elbow
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• 제1권2호
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• pp.242-249
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• 1998

Stiffness of the elbow joint is relatively common after trauma, ectopic ossification, bum, postoperative scar, and etc. Mild flexion deformity can be reduced by use of active or passive motion exercise, dynamic sling, hinged distractor device, or turnbuckle orthosis. But these methods have disadvantages of difficulty in gaining acceptable range of motion only with stretching exercise, re-contracture after conservative managements and poor results that flexion contracture remained. The common described operative exposures for treatment of the stiff elbow are anterior, lateral, posterior, and medial approach. Through Anterior, lateral and medial approach each has not access to all compartments of the elbow. But, posterior approach has benefits that access to posterior, medial and lateral aspects of the elbow and as needed, fenestration to the olecranon fossa that produces a communication between the anterior and posterior compartments of the elbow are possible. From June 1991 through April 1997, 11 patients who had posttraumatic stiff elbow, were treated with debridement arthroplasty through the posterior approach. The purpose of this study are to introduce technique of the debridement arthroplasty and to evaluate final outcomes. With regarding to preoperative pain degree, mild degree matches to 3 cases, moderate to 3 cases, and severe to 2 cases. In preoperative motion, flexion was average 85° and extension was 30°. Postoperatively nine patients had got the complete relief of pain and two patients continued to have mild pain intermittentely. Postoperative flexion improved to 127° and extension to 2°, so that elbow flexion had improved by an average of 42° and elbow extension by 28°. On the objective scale all patients had good or excellent results and they all felt that they were improved by operation. Debridement arthroplasty is one of excellent procedures for the intractable stiff elbow if it is not unstable or it has not incongrous. But it need a meticulous operative technique and a well-programmed rehabilitation.

• Clinics in Shoulder and Elbow
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• 제8권1호
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• pp.49-56
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• 2005

Purpose: To review the surgical results of stiff elbow using the posterior extensile approach which provides a wide surgical view with a single posterior skin incision. Materials and Methods: From February 1999 to May 2002, we performed 6 surgical correction of stiff elbow using posterior extensile approach and followed the patients more than 1 year. In order to get better result, we performed cadaver study (four elbows of two fresh cadavers). Average duration of follow up was 15.7 months $(14{\sim}21)$. Functional results was analyzed using Brobery and Morrey analysis scale. Results: The approach through the plane between the extensor carpi radialis longus and the extensor carpi radialis brevis was ideal, because it preserves normal anatomy and provides a wide surgical view of the anterior joint. The posterior joint could be approached directly between the medial head of the triceps brachii and brachialis medially, the lateral head of triceps brachii and brachioradialis laterally. In all patients, an improved ROM was obtained with intra and extra-articular adhesiolysis: an average $61.7^{\circ}$ improvement $(50{\sim}75)$. Functional results were as follows: five excellent, one good. In addition, the patients' satisfaction was high since the scar from the operation was only a single line at the posterior surface of the elbow. Conclusion: In the treatment of stiff elbow, posterior extensile approach is thought to be useful because this method provides wide anterior and posterior surgical view.