• International Journal of Advanced Culture Technology
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• v.6 no.2
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• pp.9-15
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• 2018

The purpose of this study was to assess risk indicators of depressive symptoms such as demographic, socio-economical domains (age, gender, marital status, education, child, religion, income, health, friendship) and personality domains (neurotic personality, self-esteem and life goal attitude) of community dwelling elderly persons. A total of 300 community-residing elderly participants aged 65+ in a metropolitan city in Korea, were recruited for this interview survey. The interview covered demographic and socio-economic characteristics, and administration of the 20-item Korean Version of CES-D, the 10-item Self-esteem, the 19-item Neuroticism and the 10-itm Goal Instability scale. The prevalence of significant depressive symptoms (CES-D scale >= 21) was 31%. Logistic regression analysis showed high risk for depression was associated with high neuroticism, less intimate friendship, high goa1 instability, and childlessness, respectively in the order of significance. Factors in the personality domains were more strongly associated with depressive symptoms than factors in the socio- economical domains. Both cultural and universal meaning of the findings was discussed with regard to intervention.

• The Journal of Industrial Distribution & Business
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• v.8 no.5
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• pp.35-42
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• 2017

Purpose - This study investigated small business members' cognition of happiness in accordance with changes of employment environment at the nation's industrialization. The study verified effects of labor workers' psychological wellbeing conditions upon life satisfaction as well as the effects of job burden and family burden of employment instability. Research design, data, and methodology - The subjects were small business workers in Seoul and Metropolitan areas. The author collected 150 copies of effective questionnaires. Regression analysis, hierarchical analysis and 3-stage mediation regression analysis were done. Results - The findings of this research was that psychological wellbeing factors alleviated job burden and family burden to increase satisfaction with life. Employment instability moderated between job burden and satisfaction with life, job burden between environmental control and satisfaction with life, and family burden between goal and satisfaction of life. Members needed sub factors of psychological wellbeing, especially reflection for self-acceptance. Conclusions - This study inspected effects of small business workers' psychological wellbeing upon life satisfaction at changes of management environment as well as labor environment to verify effects of job burden, family burden and employment instability and to find out conditions of human resources management from point of view of small business and workers.

• Journal of Korean Neurosurgical Society
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• v.29 no.11
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• pp.1469-1475
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• 2000

Objective : The goal of this study was to evaluate the clinical outcome of the posterior C1-2 transarticular screw fixation without C1-2 sublaminar wiring in atlantoaxial instability. Methods : Between Apr. 1995 and Feb. 2000, we used this technique in treat randomly selected 17 patients (11 men, 6 women) who had atlantoaxial instability. The causes of instability were : type II-A odontoid process fracture(10 cases) ; type II-P odontoid process fracture(1 case) ; Os odontoideum(2 cases) ; transverse ligament laxity due to rheumatoid disease(1 case) ; and, transverse ligament injury without bone fracture(3 cases). All cases were operated with posterior C1-2 transarticular screw fixation with 3.5mm cortical screw and interlaminar iliac graft without sublaminar wire fixation. The mean follow-up period was 28 months(5 to 58 months) and the mean age at the time of operation was 41 years(15 to 68 years). All Patients were allowed to ambulate with Philadelphia neck collar on the first post-operation day. Results : Bony fusion was successfully achieved in all cases demonstrated at 3-month follow-up studies. There was no operative mortality or morbidity. Conclusion : The authors conclude that the posterior transarticular screw fixation without C1-2 sublaminar wiring provide adequate stability with high bony union rate in atlantoaxial instability of various causes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.447-448
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• 2008

The goal of this study is to find flame dynamic behavior using a transverse fuel injection in a model combustor, and is to investigate main causes of unstable combustion in a liquid-fueled combustor. For transverse fuel injection into air cross flow, spray result shows similar tendency with Wu et al.[1998] until spray arrives at flame-holder. However, passing through flame-holder, fuel inflow into recirculation region of flameholder is not sufficient so it makes large difference between shear flame and recirculation flame behind flameholder. In combustion tests, the stable flame shows a kind of shear flames and low peaks of dynamic pressure frequencies. On the other hand, unstable flame shows periodic detached flame in recirculation zone and a strong peak of dynamic pressure frequency. The instability frequency is highly affected by influx air velocity, air temperature, equivalence ratio and wake or vortex shedding frequency behind the flameholder.

• Wind and Structures
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• v.8 no.1
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• pp.1-12
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• 2005

A simplified analysis able to point out the most relevant geometrical and aerodynamic parameters that can influence the flutter of long span modern bridges is the aim of the paper. With this goal, by using a continuous model of the suspension bridge and by a quasi stationary approach, a simple formula of the combined vertical/torsional flutter wind speed is given. A good agreement is obtained comparing the predictions from the proposed formula with the flutter speeds of three modern suspension or cable stayed bridges: the Great Belt East Bridge, the Akashi and Normandie bridges. The paper ends with some comments and comparisons with the well known Selberg formula.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.2
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• pp.168-172
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• 2015

In general, open-loop fiber-optic gyroscopes (FOG) are less stable than closed-loop FOGs but they offer simpler implementation. The typical operation time of line-of-sight (LOS) stabilization systems is a few seconds to one hour. In this paper, a open-loop fiber optic gyroscope (FOG) for LOS applications is designed and implemented. The design goal is aimed at implementing a low cost, compact FOG with low Angle Random Walk (ARW) (< $0.03deg/\sqrt{h}$) and bias instability (< 0.25deg/h). The FOG uses an open-loop all-fiber configuration with 100M PM fiber wound on a small diameter spool. In order to get the design goal, digital signal processing techniques for signal detection, modulation control and compensation are designed and implemented in FPGA.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.11-18
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• 2019

One of the key objectives of control systems is to maintain a system in a specific stable state. To achieve this goal, a variety of control techniques can be used and it is often uses a feedback control method. As known this kind of control methods requires mathematical model of the system. This article presents seesaw unstable system with two propellers which are controlled without use of a mathematical model instead. The goal was to control it using training data. For system control we use a logistic regression technique which is one of machine learning method. We tested our controller on the real model created in our laboratory and the experimental results show that instability of the seesaw system can be fixed at a given angle using the decision boundary estimated from the classification method. The results show that this control method for structural equilibrium can be used with relatively more accuracy of the decision boundary.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.277-280
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• 2008

Enhancing the positioning precision is the primary pursuit of GPS users. To achieve this goal, most studies have focused on the relationship between GPS receiver clock errors and GPS positioning precision. This study utilizes undifferentiated phase data to calculate GPS clock errors and to compare with the frequency of cesium clock directly, thus verifying estimated clock errors by the method used in this paper. The relative frequency offsets from this paper and from National Standard Time and Frequency Laboratory of Taiwan match to $1.5{\times}10^{12}$ in the frequency instability, suggesting that the proposed technique has reached a certain level of quality. The built-in quartz clocks in the GPS receivers yield relative frequency offsets that are 3 to 4 orders higher than those of rubidium clocks. The frequency instability of the quartz clocks is on average two orders worse than that of the rubidium clock. Using the rubidium clock instead of the quartz clock, the horizontal and vertical positioning accuracies were improved by 26-78% (0.6-3.6 mm) and 20-34% (1.3-3.0 mm), respectively, for a short baseline. These improvements are 7-25% (0.3-1.7 mm) and 11% (1.7 mm) for a long baseline. Our experiments show that the frequency instability of clock, rather than relative frequency offset, is the governing factor of positioning accuracy.

• Journal of Korean Foot and Ankle Society
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• v.15 no.4
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• pp.187-194
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• 2011

Ankle injuries may involve the distal tibiofibular syndesmosis and can be associated with a variable degree of trauma to the soft tissue and osseous structures that play an important role in ankle joint stability. Ankle syndesmotic injury may occur solely as a soft tissue injury or in association with variable ankle fractures. Ankle syndesmotic injury does not necessarily lead to ankle instability; however, the coexistence of deltoid ligament injury critically destabilizes the ankle joint. The prevalence of these injuries may be higher than previously reported. The diagnosis of syndesmotic injury as not always easy because isolated ankle sprains may be missed in the absence of a frank diastasis and syndesmotic instability may be unnoticed in the presence of bimalleolar ankle fractures. Controversies arise at almost every phase of treatment includings : type of fixation(screw size, type of implant), number of cortices required for fixation and of need for hardware removal. Regardless of controversies, the most important goal should be restore and maintain the normal tibiofibular relationship to allow for healing of the ligamentous structures of the syndesmosis.

• Journal of Korean Foot and Ankle Society
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• v.16 no.2
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• pp.128-134
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• 2012

Purpose: To design novel balance tests to assess FAI and evaluate whether these tests are affected by BMI or gender, with the goal of developing reliable FAI assessment tests that are not influenced by these factors. Materials and Methods: Participants included 20 young, healthy volunteers, 12 males and 8 females, with a mean age of $24{\pm}4$ years and a mean BMI of $23{\pm}2.28$. None of the subjects had known ankle instability. The following tests were assessed in each participant: single leg balance (SLB), percentage of leg press (PLP), single leg cycling (SLC), one leg squat (OLS), multiple direction reach-front/back/side (MDR-F/B/S), single leg hop (SLH), two leg jump (TLJ) and side step (SS). Data were analyzed using the SPSS 12.0 software program with ANOVA and t-test used. Results: When grouped by BMI, we found that despite differences in BMI, the performances of all subjects were equivalent except for the one-leg-squat test, for which the mean ratios for underweight ($1.69{\pm}0$), normal weight ($1.05{\pm}0.19$), and overweight ($0.93{\pm}0.30$) individuals were significantly different (p=0.02); ratios for SLB (p=0.273), SLC (p=0.903), PLP (p=0.664), MDR-F/B/S (p=0.498, 0.908, and 0.503, respectively), SLH (p=0.332) were not significantly different. When calculated according to gender, we found that the OLS (p=0.013) and MDRS (p=0.034) were significantly different, while parameters for all the remaining tests were not affected. Conclusion: We found that the SLB, PLP, SLC, MDR-F/B, and SLH ratios were unaffected by BMI or sex and, therefore, are reliable parameters for assessing ankle instability.