• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.1
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• pp.86-94
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• 2023

In this study, a supplementary detail capable of restraining out-of-plane deformation was proposed for steel slit dampers, and a constant amplitude cyclic loading test was performed with the application of the proposed detail and the shape ratio of the damper as variables. Repeated hysteresis and cumulative plastic deformation according to the test results were analyzed. Repeated hysteresis of the slit damper with the proposed detail showed a stable spindle-shaped hysteresis within the set variable range, and no out-of-plane deformation of the damper was observed until ultimate state. It was confirmed that the restraining panel effect through the application of the proposed details is effective in terms of both the strength and deformation capacity of the damper. In addition, experimental parameters for the fatigue curve evaluation of slit dampers were derived in this study. Based on the results, it is judged that quantitative comparison of structural performance with various types of seismic devices will be possible in the future.

• The Journal of the Acoustical Society of Korea
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• v.29 no.8
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• pp.504-508
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• 2010

In conventional diagnostic ultrasound strain imaging, when displaying strain image on a monitor, human visual characteristics are utilized such that hard regions are displayed as dark and soft regions are displayed as bright. Thus, hard regions representing tumor or cancer are displayed as dark, decreasing the contrast inside the lesion. Because the lesion area is stiff and thus displayed as dark, a method of inverting the image brightness and thereby increasing the contrast in the lesion for better diagnostic purposes is proposed wherein a postcompression signal is extended in the time domain by a factor corresponding to the reciprocal of the amount of the applied compression using a technique termed globally uniform stretching. Experiments were carried out to verify the proposed method on an ultrasound elasticity phantom with radio-frequency data acquired from a diagnostic ultrasound clinical scanner. It is found that the new method improves the contrast-to-noise ratio by a factor of up to about 1.8 compared to a conventional strain imaging method that employs a reversed gray color map without globally uniform stretching.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.69-77
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• 2011

Purpose: This study was retrospectively performed to compare the clinical outcomes of modified Brostrom procedures using the single suture anchor and the double suture anchor for chronic lateral ankle instability. Materials and Methods: Thirty-seven patients were followed up for more than 1 year after the modified Brostrom procedures using suture anchor. Single surgeon treated seventeen cases with single suture anchor and 20 cases with double suture anchor. The clinical evaluation was performed according to the Karlsson scale and Sefton grading system. Radiologic measurement of the talar tilt and anterior talar translation was performed through anterior and varus stress radiographs using Telos device. Results: The Karlsson scale had improved significantly from preoperative average of 45.2 points to 89.4 points in single suture anchor group, and from 46.4 points to 90.5 points in double suture anchor group. According to the Sefton grading system, 15 cases (88.2%) in single suture anchor group and 18 cases (90%) in double suture anchor group achieved satisfactory results. The talar tilt angle and anterior talar translation had improved significantly from preoperative average of $13.6^{\circ}$ and 8.6 mm to $5.4^{\circ}$ and 4.1 mm in single suture anchor group, from $14.1^{\circ}$ and 8.4mm to $3.9^{\circ}$ and 4 mm in double suture anchor group. Double suture anchor technique was significantly superior in postoperative talar tilt. Conclusion: Single and double suture anchor techniques produced similar clinical and functional outcomes except for talar tilt, which was significantly superior in double suture anchor group. Both modified Brostrom procedures using the single and double suture anchor appear to be effective treatment methods for chronic lateral ankle instability. Further evaluation of clinical outcomes and biomechanical studies in athletes are needed.

• The Monthly Diabetes
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• s.151
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• pp.50-51
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• 2002

당뇨병성 막망증은 지속적인 고혈당과 이에 따른 대사이상으로 망막의 미세혈관이 점차 변형, 폐쇄되어 망막으로의 원활한 혈액공급이 되지 못하고 혈관투과성이 증가하여 망막에서 신생혈관이 생성되는 질환이다. 진행된 후에 치료를 통한 시력호전이 불가능하므로 조기진단 및 적절한 관리가 중요하나, 치료가 가능한 초기질환 외에 당뇨병성 망막증이 상당히 진행된 경우에도 주관적 증상이 없는 경우가 많다. 따라서 시력장애 등의 증상이 나타난 후에는 이러한 예방적인 조치를 취할 수 있는 시기를 지나치는 수가 많다.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.35-43
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• 2011

The area to be studied is the place where the main line rail way will be constructed in accordance with the scheduled construction project of Yeongju dam, and is a fold and mylonite zone over several km that is formed by ductile-shearing effect. The ductile shear zone, which has been transformed by faulting for long geological time, shows a complicated geological structure. Due to the recrystallization of mineral caused by transformation in deep underground (>8km), a mylonite zone with lamellar structure has properties distinguished from other fault zones formed by transformation near earth surface <2km). To see the properties of mylonite, this study analyzed the transformation rate of sample rocks and the shape of constriction structure accompanied with transformation. While the transformation of fault zone shows a round oblate, the mylonite zone shows a prolate form. Transformation rate in fault zone was measured to be less than 1.2 compared to the state before transformation while the measured rate in mylonite zone was 2.5 at most. Setting the surface of discontinuity as the base, the unconfined compressive strength of slickenside can be categorized in sedimentary rocks, and a change of strength was observed after water soaking over certain time. Taking into account that the weathering resistance of the rock based on mineral and chemical organization is relatively higher, its engineering properties seems to result from the shattered crack structure by crushing effect. When undertaking tunnel construction in mylonite zone, there should be a special care for the expansion of shattered cracks or the fall of strength by influx of ground water.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.111-121
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• 2016

In this study, measurements were conducted by image processing to do an in-depth evaluation of strain of rebar in a uniaxial tension test. The distribution of strain and the necking region were evaluated. The image processing is used to analyze the color information of a colored image, so that the parts consistent with desired targets can be distinguished from the other parts. After this process, the image was converted to a binary one. Centroids of each target region are obtained in the binary images. After repeating such process on the images from starting point to the finishing point of the test, elongation between targets is calculated based on the centroid of each target. The tensile test were conducted on grade 60 #7(D22) and #9(D29) rebars fabricated in accordance with ASTM A615 standards. Strain results from image processing were compared to the results from a conventional strain gauge, in order to see the validity of the image processing. With the image processing, the measuring was possible in not only the initial elastic region but also the necking region of more than 0.5(50%) strain. The image processing can remove the measuring limits as long as the targets can be video recorded. It also can measure strain at various spots because the targets can easily be attached and detached. Thus it is concluded that the image processing helps overcome limits in strain measuring and will be used in various ways.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.193-204
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• 2007

Deformation strength($S_D$) is a property which shows relatively good correlation with rut resistance of asphalt mixtures at high temperature. The Asphalt Pavement Analyzer (APA) is widely used as an equipment for estimating rut resistance of asphalt mixtures. The APA was used as corresponding property of the $S_D$ to estimate rutting resistance of asphalt mixtures. Many data were collected to establish the correlation of $S_D$ with APA. For $S_D$ test, the specimen is submerged into the $60^{\circ}C$ water for 30 minutes before applying a vertical load at the speed of 50mm/min to obtain peak load (P) and deformation (y) for $S_D$ calculation. For the same materials, APA test was performed. Relation of the $S_D$ with APA rut depth was evaluated using regression analysis. The $R^2$ value was 0.76, indicating this simple test procedure being a possible method for predicting deformation resistance of asphalt concretes at high temperature. It was also shown that, using the regression model, minimum value(s) of $S_D$ of surface course asphalt mixture or binder course for a particular road level can be determined. The limit values may be possible to use as cut-off value(s) of asphalt mixtures for the layer after further elaborated studies.

• Food Science and Industry
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• v.52 no.2
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• pp.130-139
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• 2019

Safety of genetically modified foods (GM foods) in Korea is evaluated according to "Food Sanitation Act" and "Regulation on safety evaluation for GM foods" based on the concept of substantial equivalence. In which cases a person who imports, develops or manufactures GM foods for the purpose of eating imports GM foods for the first time, he/she shall undergo a safety evaluation of the relevant foods, etc. by Ministry of Food and Drug Safety (MFDS). And in which cases ten years have elapsed since GM foods underwent safety evaluation, they shall be re-evaluated for their safety. As of April 2019, a total of 199 events have been approved by MFDS and they are 169 events of GM crops including soybean (29), maize (87), cotton (29), canola (14), sugar beet (1), potato (4), alfalfa (5), 6 events of GM microorganisms (GMM) and 24 events of GM food additives originated from GMM.

• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.21-29
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• 2012

Ground failure by liquefaction can occur not only during shaking but also as the result of the post-liquefaction process after an earthquake. During the process of ground deformation and failure, excess pore water pressure in soil is redistributed, which can then lead to changes in the effective stress of soils. Therefore, in order to provide a further understanding of the phenomenon, we have to estimate the properties of effective stress during the recompression process in post-liquefaction as well, not only the total amount of pore water drained. The primary objectives of this study are to determine and compare the recompression properties in the post-liquefaction process in terms of the relationship between volumetric strains and mean effective stresses under the various conditions of relative density and shear stress history. In all experimental cases, the volumetric strains increase greatly in the low effective stress level, almost to the zero zone, and granite soil, which has fine grains, undergoes gradual changes in the relationship between volumetric strains and mean effective stresses compared with fine sand. And, we can also find that recompression properties in the post-liquefaction process by cyclic loading depend highly on the dissipation energy and maximum shear strain, and this fact can be obtained in all cases regardless of the existence of fine content, relative density, and loading history. Especially, granite soil having fine grains can be defined uniformly in the relationship between dissipation energy and maximum volumetric strain, while fine sand cannot be so uniformly defined.

• The korean journal of orthodontics
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• v.40 no.1
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• pp.16-26
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• 2010

Objective: The purposes of this study were to evaluate the force and stress depending on the type, deflection and thickness of the materials and to evaluate the mechanical properties of thermoplastic materials after repeated loading. Methods: Four types of thermoplastic products were tested. Force until the deflections of 2.0 mm and the stress when the materials were restoring to its resting position were evaluated. The mechanical properties of thermoplastic materials evaluated after 5 repeated loading cycles. Results: The interaction was observed between the thickness and the deflection (p < 0.05) from the regression equation. Thickness and amount of deflection rather than products and materials showed the largest effect on force and stress. In all products, at least 159 gf of force was required for more than 1.0 mm deflection or when materials with 1.0 mm thickness were deflected. The stress recorded was more than 19 gf/$mm^2$. During repeated loading, each group showed significant difference on the force and the stress (p < 0.01), 10 - 17% reduction of force and 4 - 7% reduction of stress in average. Conclusions: Proper thickness of thermoplastic materials and deflection level of tooth movement should be decided for the physiologic tooth movement. Force decay after repeated loading should be considered for the efficient tooth movement.