• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.218-228
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• 2007

Modem concepts of gait rehabilitation after stroke favor a task-specific repetitive approach. In practice, the required physical effort of the therapists limits the realization of this approach. Therefore, a mechanized gait trainer enabling nonambulatory patients to have the repetitive practice of a gait-like movement without overstraining therapists was constructed. In this study, we developed an active gait training system for patients with gait disorder. This system provides joint movements to patients who cannot carry out an independent gait. It provides a normal stance-swing ratio of 60:40 using an eccentric configuration of two gears. Joint motions of the knee and the ankle were evaluated with using the 3D motion analysis system and compared with the results from the multi-body dynamics simulation. In addition, clinical investigations were also performed for low stroke patients during the 6-week gait training. Results from the dynamics simulation showed that joint movements of the knee and the ankle were affected by the gear size, the step length and the length of the foot plate, except the radius of curvature of the foot guide plate. Also, the 6-week gait training revealed relevant improvements of the gait ability in all low subjects. Functional ambulation category levels of subjects after training were 2 in three patients and 1 in a patient. The developed active gait trainer seems feasible as an adjunctive tool in gait rehabilitation after stroke.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.383-390
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• 2004

This study has focused on the possibility for recycling tailings from the Sangdong tungsten mine as admixture for concrete. The XRD(X-ray diffraction analysis) and PSA(Particle size analysis) were performed to find mineralogical characteristics. As a result of XRD analysis, the tailings from the Sangdong tungsten fine were composed of quartz, chlorite, anorthite and cordierite etc. As a result of KSLT for cement mortar mixed with tailings from the Sangdong tungsten mine, most of heavy metals were determined as below the guide line for waste material. In addition, the setting time and compressive strength of cement mortar mixed with tailings from the Sangdong tungsten mine were investigated. It was indicated that the initial and final set were retarded according to increasing replacement of tailings from the Sangdong tungsten mine. The compressive strength of mortar was decreased with increasing replacement of failings from the Sangdong tungsten mine.

• Journal of Preventive Medicine and Public Health
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• v.41 no.2
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• pp.121-127
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• 2008

Objectives : This study investigated the health information such as the general health information, the health product information, and the hospital information, and we wanted to identify the association between internet health information and the health related behavior by analyzing the process after people search the Internet. Methods : A telephone survey with structured questionnaire was performed by trained surveyors. The respondents were sampled proportionate to the Korean demographic distribution with considering the city size and the populations' ages and gender. The survey was conducted from October 2006 to November 2006. Results : Out of 3,758 successfully connected persons of age 20 or more, 871(23.2%) respondents had used Internet health information during the last year. The purposes of searching the Internet for health was, 1) to get general health information (717 cases, 81.0%), 2) shopping for health product (109 cases, 12.3%) and 3) seeking information about hospital selection (59 cases, 6.7%). Our research showed that the process after searching the Internet for health information depends on the purpose of the search. 68.8% of the searchers for general health information, 67% of the searchers for health product shopping and 64.4% of the searchers seeking information to guide hospital selection were satisfied with their Internet search. However one third of the respondents reported not being satisfied with the result of the search. Conclusions : Unsatisfied consumers with internet health information tended to ask lay referrals from others or they gave up seeking health information. The health information system should be improved to increase the accessibility and to provide reliable and effective information. Also, a more user-centric community is needed in order to strengthen the effective role of lay referrals among the internet users.

• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1217-1225
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• 2015

Survey research, data is commonly collected through a sample design with complex design features that allow the relative efficiency on the precision of an estimator to be measured using the concept of the design effect compared to simple random sampling as a reference design. This concept is most useful when the design effect can be expressed as a function of various design features. We propose a design effect formula suitable under a stratified multistage sampling by generalizing Gabler et al. (1999, 2006)'s approaches for multistage sampling. Its use can either guide improvement in the design efficiency when in design stage or enable the evaluation of the adopted design features afterwards.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.41-48
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• 2011

Warm-Mix Asphalt(WMA) mixtures, which meet environmental protection and have high energy efficiency, are emerging as an alternative to hot-mix asphalt mixtures. The objective of this study is to evaluate WMA made with Aspha-min in the laboratory and to compare the design results accomplished by new Mechanistic-Empirical Pavement Design Guide(MEPDG) with control mixture. An asphalt mixture with a nominal maximum size of 12.5mm and PG64-28 binder was used. Resilient modulus tests for a control mixture and WMA with 0.3% and 0.5% of Aspha-min were conducted. The results obtained by MEPDG after inputting the test output into the design indicated that the predicted rut depth of WMA using Aspha-min was much lower than that of control mixture, and showed that WMA was more resistant to rutting than control mixture.

• Transactions of Materials Processing
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• v.29 no.3
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• pp.157-162
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• 2020

Blind rivet nuts are increasingly used in automotive for the joining of sheets. Their application, however, requires appropriate design guides to prevent catastrophic events arising from the failure of joints. In this study, the shaft shape of a frequently used M8 blind rivet nut is optimized based on 3D numerical analysis of the blind rivet nut considering the characteristics of thread. The thread needs to be modeled to suitably consider the fastening of the M8 bolt after the crimping process. FE analysis showed that while the friction in the contact between crimp flange and plate has no significant effect on the crimp geometry, shaft thickness (t) and shaft height (h) are the most significant design variables. The parameter study including various combinations of t and h reveals that they affect the gap (the distance between the crimped flange and the plate that develops through riveting) and the load acting on the plate. The gap is an indicator of the tightening force. It is found that t is inversely proportional to the gap, and proportional to the load, whereas h is proportional to the gap and inversely proportional to the load. Based on our FE analysis results, we propose the range 0.062 < t/h < 0.1 to ensure sufficient fastening (high clamping load, small gap) of the M8 blind rivet nut. The design guide for determining the t/h ratio proposed in this study can be used for general quantitative analysis of the size and the t/h ratio of blind rivet nuts.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.365-373
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• 2010

Many studies on safety issues of human-machine interaction are being conducted, especially taking emergency situations into consideration. In light of this view, the importance of objective and reliable measurement of users' reactions under emergency situations is becoming more important than ever in reflecting such issues in the design of everyday things. However, despite the need to consider the human-machine interactions and human performances at the design stage, there were few studies which considered human performances and behaviors under emergency situations. This study is about an evaluation method and design guide to include such human performances under emergency situations during human-machine interactions. This is achieved through an experiment where operators are instructed to press the emergency button at an experimentally designed location under a random emergency situation. By analyzing the results in a human factors perspective, the response time and the accuracy of the operators' behaviors are explained. Analysis revealed that in designing the center fascia for automobiles, there is a tradeoff between response time and accuracy, and the optimal size of buttons differ in each part of the center fascia. This method is expected to be applicable to industrial situations to derive optimal position for emergency buttons.

• Journal of the Korea Computer Graphics Society
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• v.24 no.4
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• pp.39-54
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• 2018

Recently, augmented reality(AR) based building information applications using a smart phone provide information in the static form irrespective of the distance between a user and a target building. If many target buildings are located close to each other, discrimination of information is reduced due to overlapping information objects. Furthermore, it is difficult to intuitively grasp the current position of the user in the previous AR-based applications. In this paper, to solve these limitations, we have designed and implemented a novel building information system in which the location and size of information objects are adaptively displayed according to locations of a user and target buildings, and which allows users to intuitively understand their location by providing a 3D map that displays the user's location and all target buildings within a given distance in real-time. The AR-based building information application proposed in this paper focuses on the building guide in Deoksu Palace in Jung-gu, Seoul.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.173-181
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• 1997

The objective of this study is to obtain the mechanical characteristics of prefoarmed lightweight foamed concrete using the polymer ham agent which has high lightness. flowability and strength. For this purpose, the prefoarmed lightweight foamed concrete which was developed to have flow value over 180mm. unit weight between 0.38t/$m^3$ and 0.64t/$m^3$, and compressive strength about 30kg/$cm^2$ was used. This paper presents extensive test data on Young's modulus. Poisson's ratio, stress-strain curve, the characteristics of strength of the foamed concrete and also presents the mechanical characteristics of the foamed concrete with different foam sizes. It is expected that this study provides an importance guide to design and manufacture lightweight foam concrete, so that it helps to expand its structural use.

• Journal of IKEEE
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• v.18 no.4
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• pp.559-565
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• 2014

A 3 dB coupler has been designed and implemented using the most commonly used double-sided FR4 boards. The coupling and the bandwidth of the coupler are enhanced with the enlarged overlapped area of the coupler. Major design parameters are plotted as a design guide and the parameters are verified by simulation and measurement. The size of the manufactured coupler is $30{\times}14mm^2$. Its measured insertion loss and phase difference are 0.6 dB and $90.5^{\circ}$ at center frequency of 2.5 GHz, respectively. The operating frequency range is 1.72 GHz to 3.08 GHz for $3.6{\pm}0.5dB$ insertion loss. The coupler has the performance similar to that of conventional Lange coupler, and implementation of the coupler is easy and cheap with wide metal width and spacing and no additional wire bonding process.