• 대한인간공학회지
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• 제36권2호
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• pp.145-156
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• 2017

Objective: This study aims to compare the usability of the adaptive touch design method with that of the height adjustable design method that are applied to the Korean QWERTY keyboard and Naratgul keyboard on smartphones, examine the results, and present practical implications. Background: Smartphone manufacturers have failed to satisfy every user with their uniform touch keyboard designs that do not consider the high use rates of keypad use. In reality, touch keyboard designing customized for every individual is impossible, but there need to be researches on was to improve usability by having touch areas changed automatically depending on user behaviors or having users adjust the keyboard height depending on their hand size. Method: As for the design methods, an object group was given smartphones with the adaptive touch design method and the other group those with the height adjustable design method. As they entered the same characters in the smartphones, typing error rates and text input speed were measured and the average values were compared. 35 individuals who would frequently use smartphones in daily life participated in the experiment. The group variable was the type of touch keyboards, and the test variables were typing error rates and text input speed, for which a T-test was implemented. Results: As for the QWERTY keyboard, the significant improvement effect was verified as the typing error rate of the adaptive touch design method was 4.21% but that of the height adjustable design method was 3.28% although there was no significant difference in terms of text input speed. As for the Naratgul keyboard, in contrast, the typing error rate of the adaptive touch design method was 2.5% while that of the height adjustable design method was 1.48%, which indicates a measure of improvement, but the effect was not significant. On the other hand, the text input speed per minute was improved as much as 22.2%, which is significant. Conclusion: First, the Korean touch keyboard usability of the adaptive touch design method and that of the height adjustable design method, when applied to Model A of Company L, showed significant difference from each other. Second, the height adjustable design method was applied to the QWERTY keyboard, the typing error rate was improved significantly. This indicates that as the keyboard height was raised, the number of buttons within the range of fingering decreased, decreasing the touch bias was reduced. Third, the height adjustable design method was applied to the Naratgul keyboard, the text input speed was improved. Application: When the QWERTY keyboard was applied to a smartphone as small as 5.5inch or less, it is highly probably that the height adjustable design method decreases the typing error rate. It may be considered to develop additional UX functions to make the keyboard font larger or give users the option to adjust button intervals in utilization of the SW advantages of the height adjustable design method.

• Tribology and Lubricants
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• 제16권4호
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• pp.247-252
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• 2000

As the demand for higher areal recording densities requires a lower flying height of the slider, the variation of the flying height of the slider during drive operation becomes of great concern. The variation of the flying height is closely related with the slider design parameters such as air bearing shape, cavity depth, shallow step depth, crown, camber, pitch offset, roll offset, gram load, and so on. The objective of this work is to optimize the cavity depth and the shallow step depth, which are the control factors in air bearing design, using Robust Design method. It was found that the shallow step depth was statistically significant in affecting the variation of flying height, therefore the level of the shallow step depth should be chosen to minimize the variation of flying height.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권6호
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• pp.1007-1019
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• 2015

The determination of the required seawall height is usually based on the combination of wind speed (or wave height) and still water level according to a specified return period, e.g., 50-year return period wind speed and 50-year return period still water level. In reality, the two variables are be partially correlated. This may be lead to over-design (costs) of seawall structures. The above-mentioned return period for the design of a seawall depends on economy, society and natural environment in the region. This means a specified risk level of overtopping or damage of a seawall structure is usually allowed. The aim of this paper is to present a conditional risk probability-based seawall height design method which incorporates the correlation of the two variables. For purposes of demonstration, the wind speeds and water levels collected from Jiangsu of China are analyzed. The results show this method can improve seawall height design accuracy.

• Structural Engineering and Mechanics
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• 제74권4호
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• pp.533-545
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• 2020

An optimal design method for a spoke double-layer cable-net structure (SDLC) is proposed in this study. Simplified calculation models of the SDLC are put forward to reveal the static responses under vertical loads and wind loads. Next, based on an energy principle, the relationship among the initial prestress level, cross-sectional areas of the components, rise height, sag height, overall displacement, and relative deformation is proposed. Moreover, a calculation model of the Foshan Center SDLC is built and optimized. Given the limited loading cases, material properties of the components, and variation ranges of the rise height and sag height, the self-weight and initial prestress level of the entire structure can be obtained. Because the self-weight of the cables decreases with increasing of the rise height and sag height, while the self-weight of the inner strut increases, the total weight of the entire structure successively exhibits a sharp reduction, a gradual decrease, a slow increase, and a sharp increase during the optimization process. For the simplified model, the optimal design corresponds to the combination of rise height and sag height that results in an appropriate prestress level of the entire structure with the minimum total weight.

• Tribology and Lubricants
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• 제35권1호
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• pp.37-43
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• 2019

This paper presents an optimization method to determine the shoulder height of an angular contact ball bearing by 3D contact analysis using nondimensional-shaped variables. The load analysis of the ball bearing is performed to calculate the internal load distributions and contact angles of each rolling element. From the results of bearing load analysis and the contact geometry between the ball and inner/outer raceway, 3D contact analyses using influence function are conducted. The nondimensional shoulder height and nondimensional load are defined to give the generalized results. The relationship between the shoulder height and radius of curvature of the shoulder under various loading conditions is investigated in order to propose a design method for the two design parameters. Using nondimensional parameters, the critical shoulder heights are optimized with loads, contact angles, and conformity ratios. We also develop contour maps of the critical shoulder height as functions of internal loads and contact angles for the different contact angles using nondimensional parameters. The results show that the dimensionless shoulder height increased as the contact angle and dimensionless load increased. Conversely, when the conformity ratio increased, the critical shoulder height decreased. Therefore, if the contact angle is reduced and the conformity ratio is increased within the allowable range, it will be an efficient design to reduce the shoulder height of ball bearings.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.168-177
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• 2020

Many coastal engineering designs utilize empirical formulas containing the Equivalent Deep-water Wave Height (EDWH), which is normally given a priori. However, no studies have explicitly discussed a method for determining the EDWH and the resulting design wave heights (DEWH) under irregular wave conditions. Unfortunately, it has been the case in many design practices that the EDWH is incorrectly estimated by dividing the Shallow-water Wave Height (SWH) at the structural position with its corresponding shoaling coefficient of regular wave. The present study reexamines the relationship between the Shallow-water Wave Height (SWH) at the structural position and its corresponding EDWH. Then, a new procedure is proposed to facilitate the correct estimation of EDWH. In this procedure, the EDWH and DEWH are determined differently according to the wave propagation model used to estimate the SWH. For this, Goda's original method for nonlinear irregular wave deformation is extended to produce values for linear shoaling. Finally, exemplary calculations are performed to assess the possible errors caused by a misuse of the wave height calculation procedure. The relative errors with respect to the correct values could exceed 20%, potentially leading to a significant under-design of coastal or harbor structures in some cases.

• 대한안전경영과학회지
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• 제15권4호
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• pp.123-129
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• 2013

Among various manual materials handling tasks, pushing/pulling was known to be one of the risk factors for the low back and shoulder musculoskeletal disorders (MSDs). This study was conducted to find out an optimal solution set of the handle height and distance for 4-wheel cart with two vertical handles. Ten male college students participated in the pushing force measurement experiment. The face-centered cube design, one of the central composite designs, was applied for the experiment, and the isometric voluntary pushing force was measured in 9 treatment conditions. The second order response surface model was predicted by using the pushing strength as a response variable, and the handle height and distance as independent factors. According to the 2nd order response model, the handle height and distance showed nonlinear relationship with the isometric pushing strength. To maximize the 2nd order response model (pushing force), the handle height and distance were optimized. The optimal handle height was 'xyphoid process height - stature', and the optimal handle distance was '$1.25{\times}shoulder$ width'. When calculated using the anthropometric data of the subjects of this study, the optimal handle height was $115.4{\pm}3.4$ cm, slightly higher than the elbow height, and the handle distance was $52.9{\pm}2.3$ cm.

• Architectural research
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• 제4권1호
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• pp.1-6
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• 2002

Every year new tall buildings are being conceived, designed, and built with new schemes. Thus it is important to explore the factors that affect tall building design. Thus it is important to explore the tall building design factors. The planning and design of tall buildings require different criteria than those that exist in regular size buildings. Tall buildings are uniquely expressed by their structural systems where exterior esthetic and requirements of space drive the form and composition of the structural systems. Therefore the exploration of design factors is the key to achieve optimum building systems. Optimization as mentioned here is associated with the efficiency of the different building systems. To achieve an optimal system, there is a need for an understanding of the factors that affect on overall tall building design such as planning module, building function, lease span, floor-to-floor-height, building height (aspect ratio), structural system, environmental systems. In this paper a statistical approach will be used and will be based on data collected from the practice through a rigorous survey taken. This information is tabulated and analyzed. The major target of investigation will be lease span related to space requirement in the tall building planning. Factors related to lease spans, such as function, floor-to-floor height, planning module, building height, overall plan dimension, and plan ratio (building geometry), will be looked at carefully. IN conclusion, this approach of optimization can introduce a preliminary design guideline for tall building projects. The purpose of the paper should shed some light on the optimum tall building design criteria.

• 재활복지공학회논문지
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• 제11권4호
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• pp.349-354
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• 2017

본 논문은 개인위생(personal hygiene)을 위한 보조기기(assistive product)의 하나인, 고령자 및 장애인을 위한 높이조절 세면기의 설계 가이드라인을 제안하였다. 본 연구에서는 기존의 세면기와 프로토타입 높이조절 세면기를 이용한 생체역학적 평가를 진행하였다. 65세 이상 남성 5명(age $68.6{\pm}4.3yrs.$, height $169.8{\pm}5.7cm$, weight $70{\pm}7.7kg$)이 피험자로 참가하였으며, 피험자가 세면기 사용시 3차원 동작측정장치를 이용하여 인체각도를 측정하고, 인체모델을 이용하여 요추에 걸리는 모멘트를 추정하여 평가하였다. 이 결과로부터 최적의 높이 조절 가능 범위가 652[mm]에서 1,162[mm]인 설계 가이드라인을 제시하였다. 일반인 5명의 피험자($25.8{\pm}1.8$세, $175.5{\pm}5.8cm$, $74{\pm}15.7kg$)를 대상으로 높이 조절 세면기의 사용시 그 유효성을 평가하였으며, 그 결과 본 논문에서 제시한 높이조절 범위가 타당함을 보였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.511-516
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• 2004

The objective of this study is to optimally design FRP-concrete members of a bridge structure. Using the GENESIS7.0 that is a commercial optimization program we performed an optimal design with design parameters that consist of height, width of FRP member, height of concrete. And we practiced an optimal design with the design variables, thickness of upper flange, bottom flange, and web. The results of these studies are summarized as follows : (1) Thickness of composite-concrete is proper at over loon (2) FRP member reaches the optimal section when the width of the FRP member is 20cm its height is 10cm and the height of the composite-concrete is 12cm.