• KCI Concrete Journal
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• v.12 no.1
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• pp.57-68
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• 2000

The effect of structure size on the nominal strength of unidirectional fiber-polymer composites, failing by propagation of a kink band with fiber microbuckling, is analyzed experimentally and theoretically. Tests of novel geometrically similar carbon-PEEK specimens, with notches slanted so as to lead to a pure kink band (without shear or splitting cracks), are conducted. The specimens are rectangular strips of widths 15.875, 31.75. and 63.5 mm (0.625, 1.25 and 2.5 in and gage lengths 39.7, 79.375 and 158.75 mm (1.563, 3.125 and 6.25 in.). They reveal the existence of a strong (deterministic. non-statistical) size effect. The doubly logarithmic plot of the nominal strength (load divided by size and thickness) versus the characteristic size agrees with the approximate size effect law proposed for quasibrittle failures in 1983 by Bazant This law represents a gradual transition from a horizontal asymptote, representing the case of no size effect (characteristic of plasticity or strength criteria), to an asymptote of slope -1/2 (characteristic of linear elastic fracture mechanics. LEFM) . The size effect law for notched specimens permits easy identification of the fracture energy of the kink bandand the length of the fracture process zone at the front of the band solely from the measurements of maximum loads. Optimum fits of the test results by the size effect law are obtained, and the size effect law parameters are then used to identify the material fracture characteristics, Particularly the fracture energy and the effective length of the fracture process zone. The results suggest that composite size effect must be considered in strengthening existing concrete structural members such as bridge columns and beams using a composite retrofitting technique.

• Clinics in Shoulder and Elbow
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• v.21 no.4
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• pp.220-226
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• 2018

Background: This study introduces a surgical technique with good clinical outcome useful in the treatment of osteoporotic displaced 3- or 4-part proximal humeral fractures. Methods: From May 2014 to February 2016, 16 patients with displaced 3- or 4-part proximal humeral fractures were treated by application of a locking plate with an endosteal strut allograft via a deltoid splitting approach with a minimum follow-up of 12 months. The allograft was inserted through a fractured gap of the greater tuberosity to support the humeral head and then fixed by a locking plate with meticulous soft tissue dissection to protect the axillary nerve. Surgical outcomes were evaluated by the American Shoulder and Elbow Surgeons (ASES) and visual analogue scale (VAS) scores, radiological imaging, and clinical examination. Fixation failure on radiographs was defined as a >$5^{\circ}$ loss of neck shaft angle (NSA) compared to that on an immediate postoperative radiograph. Avascular necrosis (AVN) of the humeral head was also evaluated. Results: In all cases, complete union was achieved. The ASES and VAS scores were improved to $85.4{\pm}2.1$ and $3.2{\pm}1.3$, respectively. Twelve patients (75.0%) had greater than a $5^{\circ}$ change in NSA; the average NSA change was $3.8^{\circ}$. Five patients (31.3%) had unsatisfactory ranges of motion exhibiting a <$100^{\circ}$ active forward flexion. No axillary nerve injuries or AVN were observed at the last follow-up. One patient was converted to reverse total arthroplasty due to severe pain and functional deficit. Conclusions: Minimally invasive fixation via a locking compression plate and an endosteal fibula strut allograft in Neer classification 3-or 4-part fractures with severe osteoporosis in elderly patients can achieve good clinical results.

• Korean Journal of Materials Research
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• v.29 no.1
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• pp.1-6
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• 2019

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide($Cu_2O$) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of $Cu_2O$ is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of $Cu_2O$ while imperfections of the $Cu_2O$ thin films are removed. This study investigates the photoelectrochemical properties of $Cu_2O$. However, severe photo-induced corrosion impedes the use of $Cu_2O$ as a photoelectrode. Two candidates, $TiO_2$ and $SnO_2$, are selected for the passivation layer on $Cu_2O$ by by considering the Pourbaix-diagram. $TiO_2$ and $SnO_2$ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that $SnO_2$ is a good passivation layer for $Cu_2O$.

• Journal of Ocean Engineering and Technology
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• v.38 no.4
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• pp.164-173
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• 2024

In this study, a submerged breakwater with effective wave control and eco-friendly characteristics is developed and proposed. Hydraulic experiments are conducted to compare the hydraulic performance of a submerged breakwater and an eco-friendly double-row submerged breakwater. The hydraulic characteristics are analyzed based on wave reflections and the transmission-splitting method for each experimental cross-section. This splitting technique utilizes Goda's two-point method, which employs the spectra of two irregular superposed wave fields. In addition, the reliability of the results obtained from the hydraulic experiments is discussed by comparing the results with empirical formulas. The eco-friendly double-row submerged breakwater features approximately half the width of a typical submerged breakwater. Nevertheless, its transmission coefficient (K_T) is approximately 20% more effective, and the difference in the average reflection coefficient (K_R) values between the two is approximately 0.17. Moreover, the dissipation coefficient (K_D) shows a generally similar trend. Based on these experimental results, the hydraulic performance of the eco-friendly double-row submerged breakwater is more efficient regarding wave control, compared with a typical submerged breakwater. These hydraulic characteristics confirm that the numerical model developed for the eco-friendly double-row submerged breakwater accurately reproduces the K_T, K_R, and K_D values within ±5%.

• Archives of Plastic Surgery
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• v.46 no.1
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• pp.7-15
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• 2019

Breast animation deformity (BAD) has been reported to occur after submuscular implant placement following breast augmentation and immediate breast reconstruction. Despite its apparent impact on patients' quality of life, BAD has only recently become a topic of general concern. Its incidence and etiology have yet to be established. The aim of this systematic review was to identify papers that clearly defined and classified BAD and described how the degree of animation was assessed. We performed a search in PubMed and Embase. Studies meeting the inclusion criteria that described BAD after implant-based breast augmentation or immediate breast reconstruction were included. After screening 866 publications, four studies were included: three describing BAD after breast augmentation and one describing BAD after immediate breast reconstruction. The median percentage of patients with some degree of BAD was 58%. The highest percentages were found in patients operated on using the Regnault technique or the dual-plane technique (73%-78%). The lowest percentages were found following the dual-plane muscle-splitting technique (30%) and the triple-plane technique (33%). We found no studies meeting the inclusion criteria that analyzed BAD after prepectoral implant placement. This review of the current literature suggests that the degree of BAD is proportional to the degree of muscle involvement. Evidence is scarce, and the phenomenon seems to be underreported. Future comparative studies are warranted.

• 대한치주과학회:학술대회논문집
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• 2005.11a
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• pp.219-220
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2347-2355
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• 1996

Purpose of the present study is to develop a computational design program for shape optimization, combining the numerical optimization technique with the flow analysis code. The present methodology is then validated in three cases of aerodynamic shape optimization. In the numerical optimization, a feasible direction optimization algorithm and shape functions are considered. In the flow analysis, the Navier-Stokes equations are discretized by a cell-centered finite volume method, and Roe's flux difference splitting TVD scheme and ADI method are used. The developed design code is applied to a transonic channel flow over a bump, and an external flow over a NACA0012 airfoil to minimize the wave drag induced by shock waves. Also a separated subsonic flow over a NACA0024 airfoil is considered to determine a maximum allowable thickness of the airfoil without separation.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.22-27
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• 2006

This paper describes the development of the stream-tube based dispersion model for modeling contaminant transport in open channels. The operator-splitting technique is employed to separate the 2D contaminant transport equation into the pure advection and pure dispersion equations. Then the total variation diminishing (TVD) schemes are combined with the second-order Lax-Wendroff and third-order QUICKEST explicit finite difference schemes respectively to solve the pure advection equation in order to prevent the occurrence of numerical oscillations. Due to various limiters owning different features, the numerical tests for 1D pure advection and 2D dispersion are conducted to evaluate the performance of different TVD schemes firstly, then the TVD schemes are applied to experimental data for simulating the 2D mixing in a straight trapezoidal channel to test the model capability. Both the numerical tests and model application show that the TVD schemes are very competent for solving the advection-dominated transport problems.

• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.1111-1118
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• 2004

Natural language query is the best user interface for the users of web text retrieval systems. This paper proposes a retrieval system with expanded keyword from syntactically-analyzed structures of user's natural language query based on natural language processing technique. Through the steps combining or splitting the compound nouns based on syntactic tree traversal, and expanding the other-formed or shorten-formed keyword into multiple keyword, it shows that precision and correctness of the retrieval system was enhanced.

• Journal of the Korean Society for information Management
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• v.21 no.2
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• pp.235-248
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• 2004

For the users of information retrieval systems, natural language query is the more ideal interface, compared with keyword and boolean expressions. This paper proposes a retrieval technique with expanded keyword from syntactically-analyzed structures of natural language query as user input. Through the steps combining or splitting the compound nouns based on syntactic tree traversal of the query, and expanding the other-formed or shorten-formed into multiple keyword, it can enhance the precision and correctness of the retrieval system.