• 한국해양공학회지
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• 제30권4호
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• pp.235-242
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• 2016

In general, ship hull form design is carried out in two stages. In the first stage, the longitudinal variation of the sectional area curves is adapted from a similar mother ship to determine the volume distribution in ships. At this design stage, the initial design conditions of displacement, longitudinal center of buoyancy, etc. are satisfied and the global hydrodynamic properties of the structure are optimized. The second stage includes the local designing of the sectional forms. Sectional forms are related to the local pressure resistance in the fore- and aft-body shapes, cargo boundaries, interaction between the hull and propeller, etc. These relationships indicate that the hull sections need to be optimized in order to minimize the local resistance. The volumetric balanced (VOB) variation of ship hull forms has been suggested by Kim (2013) as a generalized, systematic variation method for determining the sectional area curves in hull form design. This method is characterized by form parameters and is based on an optimization technique. This paper emphasizes on an extensional function of the VOB considering a geometrical wave profile. We select a container ship and an LNG carrier to demonstrate the applicability of the proposed technique. Through analysis, we confirm that the VOB method, considering the geometrical wave profile, can be used as an efficient tool in the hull form design for ships.

• 한국어교육
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• 제28권1호
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• pp.221-250
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• 2017

This study aims to discuss the basic foundations to set levels and language skills for developing a Korean Proficiency Test for young and adolescent learners. Recently, there has been an increase in demand regarding young and adolescent learners from multicultural and overseas backgrounds. However, the current Korean Proficiency Test lacks the appropriate means to determine the Korean proficiency of young and adolescent learners with general purposes of language learning. Therefore, there is an urgent need for developing a specialized and new form of language assessment for young and adolescent learners who are exposed to a foreign language or a second language learning environment. The study examines and analyzes cases of foreign language examinations for young & adolescent learners; furthermore, the objectives and target were set based on the results of a needs analysis and in-depth interviews conducted among teachers and education officials in overseas Korean Hangeul Schools, international schools, elementary and secondary schools. Finally, the levels and language skills appropriate for the objectives of a proficiency test and target learners have been suggested.

• Computers and Concrete
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• 제22권6호
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• pp.573-592
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• 2018

An analytical methodology for the calculation of the flexural and the shear capacity of concrete members with Fibre-Reinforced-Polymer (FRP) bars as tensional reinforcement is proposed. The flexural analysis is initially based on the design provisions of ACI 440.1R-15 which have properly been modified to develop general charts that simplify computations and provide hand calculations. The specially developed charts include non-dimensional variables and can easily be applied in sections with various geometrical properties, concrete grade and FRP properties. The proposed shear model combines three theoretical considerations to facilitate calculations. A unified flexural/shear approach is developed in flow chart which can be used to estimate the ultimate strength and the expected failure mode of a concrete beam reinforced with longitudinal FRP bars, with or without transverse reinforcement. The proposed methodology is verified using existing experimental data of 138 beams from the literature, and it predicts the load-bearing capacity and the failure mode with satisfactory accuracy.

• 대한수학회논문집
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• 제34권1호
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• pp.279-286
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• 2019

Complex Grassmann manifolds $G_{n,k}$ are a generalization of complex projective spaces and have many important features some of which are captured by the $Pl{\ddot{u}}cker$ embedding $f:G_{n,k}{\rightarrow}{\mathbb{C}}P^{N-1}$ where $N=\(^n_k\)$. The problem of existence of cross sections of fibrations can be studied using the Gottlieb group. In a more generalized context one can use the relative evaluation subgroup of a map to describe the cohomology of smooth fiber bundles with fiber the (complex) Grassmann manifold $G_{n,k}$. Our interest lies in making use of techniques of rational homotopy theory to address problems and questions involving applications of Gottlieb groups in general. In this paper, we construct the Sullivan minimal model of the (complex) Grassmann manifold $G_{n,k}$ for $2{\leq}k<n$, and we compute the rational evaluation subgroup of the embedding $f:G_{n,k}{\rightarrow}{\mathbb{C}}P^{N-1}$. We show that, for the Sullivan model ${\phi}:A{\rightarrow}B$, where A and B are the Sullivan minimal models of ${\mathbb{C}}P^{N-1}$ and $G_{n,k}$ respectively, the evaluation subgroup $G_n(A,B;{\phi})$ of ${\phi}$ is generated by a single element and the relative evaluation subgroup $G^{rel}_n(A,B;{\phi})$ is zero. The triviality of the relative evaluation subgroup has its application in studying fibrations with fibre the (complex) Grassmann manifold.

• 분석과학
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• 제32권4호
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• pp.131-138
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• 2019

This paper reports results on the physical properties of a powder type of $Al_2O_3:C$ commonly used as a luminescence dosimeter using the LM-OSL technique. On the analysis with the general order kinetics model, the LM-OSL signal measured appeared to be composed of three components (fast, medium, slow) showing the largest area in the medium component. The photoionization cross sections of three components were distributed between $10^{-19}{\sim}10^{-21}cm^2$. The values of the thermal assistance energy were evaluated the largest in slow component and the smallest in fast component, which indicates the electrons trapped in defects attributed to slow component should be the most sensitive to thermal vibration among three components. In illumination to blue light, the fast component showed a rapid linear decay and completely disappeared after light exposure time of about 5 s. The medium component decayed with two exponential elements but the slow component did not observed any noticeable change until light exposure time of 40 s. In a dose response study, all components exhibited a linear behaviour up to approximately 10 Gy.

• 한국의류학회지
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• 제43권3호
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• pp.416-426
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• 2019

This study measured and analyzed male firefighters hand sizes as well as suggested data for developing firefighting gloves with a good fit. Accordingly, body dimensions related to the hand were measured for 100 male firefighters. Twenty-three measuring items related to the hand and lower arm were selected. The firefighters' measurement data were compared to general adult male measurements from the 6th Korean Anthropometric data to analyze the hand sizes characteristics of firefighters. As a result, height, hand circumference, hand breadth, wrist circumference, elbow-wrist length, forearm-fingertip length and firefighter weight were significantly larger than adult males. A correlation analysis for 23 items was conducted to select items used as standards for setting a size when manufacturing firefighting gloves. Hand length and circumference were selected as representative hand parts for making firefighting gloves. Cross analysis between hand length and circumference were conducted to find the section showing the highest distribution ratio. As a result, the highest sections were between 19cm and 21cm for hand circumference and between 18.5cm and 19.5cm for hand length, which may be suggested as the most important ranges.

• 한국직업건강간호학회지
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• 제30권3호
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• pp.101-109
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• 2021

Purpose: This study aimed to measure COVID-19 stress and the quantitative electroencephalography (QEEG) stress quotient and identify the coping styles of face-to-face service industry employees during the COVID-19 pandemic. Methods: This cross-sectional study administered structured questionnaires consisting of sections on general characteristics, COVID-19 stress, and coping style for stress to 21 face-to-face service industry employees between April 1 and April 18, 2021. The physical tension & stress quotient and psychological distraction & stress quotient were measured in the prefrontal lobe with QEEG. Results: Emotional easiness (r=.62, p=.002) and escape-avoidance (r=.55, p=.009) as a passive coping style were associated with COVID-19 stress, and seeking social support as an active coping style was associated with the left physical tension & stress quotient (r=.47, p=.031). Conclusion: These findings provide evidence regarding the objective status of the mental health of face-to-face service industry employees using both a self-reported scale and neuroscientific indicators, including brain quotients.

• 한국동물생명공학회지
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• 제37권1호
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• pp.42-47
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• 2022

This study aimed to determine whether hormonal hypersecretion could cause morphological problems in the mouse vagina and affect the ovaries and nearby extra uterine organs. All mice were synchronized to estrus before the experiment. Then human chorionic gonadotropin (hCG), progesterone, and testosterone were continuously administered for about 6 days to maintain hormone hypersecretion, and then morphological changes were analyzed, and Matrix metalloproteinases (MMPs) activity and Casp-3 expression were evaluated. As a result of the analysis, in the case of hCG, the morphological change did not show a significant difference from the vagina of normal estrus. In the case of progesterone, changes were observed in the mucosa zone and basal membrane, and it was confirmed that the activity of MMPs was increased in squamous epithelium cells. On the other hand, in the case of testosterone, overall changes in vaginal tissues were observed, and MMPs activity was increased to a very high level in all sections. The expression of Casp-3 was also the highest compared to other groups. Therefore, as a result of this study, it is thought that hormone hypersecretion affects the morphological changes of the vagina other than the ovaries and uterus and induces the activity of MMPs to cause morphological degeneration of tissues.

• Structural Engineering and Mechanics
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• 제81권4호
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• pp.493-502
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• 2022

Shear lag phenomenon has long been considered in numerous structural codes; however, the AISC provisions have now no longer proposed any unique equation to calculate the shear lag ratio in bolted connections for angles in general. It is noticeable that, however, codes used in this case are largely conservative and need to be amended. A parametric study consisting of 27 angle sections with equal legs and different with bolted connections was performed to investigate the effects of shear lag on the ultimate tensile capacity of angle members. The main parameters were: steel grade, connection length and eccentricity from the center of the plate, as well as the number of rows of bolts parallel to the applied force. The test results were compared with the predictions of the classical 1-x/l law proposed by Mons and Chesen to investigate its application to quantify the effect of shear lag. A parametric study was performed using valid FE models that cover a wide range of parameters. Finally, based on the numerical results, design considerations were proposed to quantify the effect of shear lag on the ultimate tensile capacity of the tensile members.

• Steel and Composite Structures
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• 제42권1호
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• pp.139-149
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• 2022

To simplify the design and reduce the construction cost of traditional multi-girder structural systems, twin I-girder structures are widely used in many countries in recent years. Due to the concern on post-fracture redundancy, however, twin girder bridges are currently classified as fracture critical structures in AASHTO specifications for highway bridges. To investigate the after-fracture behavior of such structures, a composite steel and concrete twin girder specimen was built and an artificial fracture through the web and the bottom flange was created on one main girder. The static loading test was performed to investigate its mechanical performance after a severe fracture occurred on the main girder. Applied load and vertical displacement curves, and the applied load versus strain relationships at key sections were measured. To investigate the load distribution and transfer capacities between two steel girders, the normal strain development on crossbeams was also measured during the loading test. In addition, both shear and normal strains of studs were also measured in the loading test to explore the behavior of shear connectors in such bridges. The functions and structural performance of structural members and possible load transfer paths after main girder fractures in such bridges were also discussed. The test results indicate in this study that a typical twin I-girder can resist a general fracture on one of its two main girders. The presented results can provide references for post-fracture performance and optimization for the design of twin I-girder bridges and similar structures.