• Journal of the Ergonomics Society of Korea
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• v.25 no.4
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• pp.115-119
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• 2006

To investigate the effects of independent suspension technology(IST) of hiking boot on the stability and load of foot, eight participants performed medial and lateral drop landing from 33.4cm height and 85cm distance to uneven surface while wearing normal & IST hiking boots. For the stability of foot during the drop landing, the balance angle & suspension angle and rearfoot angle was analyzed using high-speed video analysis. Also kinetic analysis using the force plate and insole pressure measurement was conducted to analyze vertical & breaking ground reaction force and pressure distribution. Not only the balance angle & suspension angle but also rearfoot angle was improved with IST boots for lateral drop landing. These results indicate the IST boots may have the suspension function which keeps the foot to be stable during landing. However the IST boots did not show any effect for medial landing. This might be related to the hardness of medial part of outsole. Therefore the softer outsole of medial part could be recommended. Furthermore the impact force & breaking force and insole pressure were reduced with IST boot. These results means that IST boot has not only cushioning effect but also good grip effect. Therefore the hiking boots applied the independent suspension function may help to reduce fatigue and prevent injury such as ankle sprain in hiking on uneven surface.

• Journal of the East Asian Society of Dietary Life
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• v.4 no.2
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• pp.17-26
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• 1994

This study was an attempt to investigate various factions, such as the calorie, nutrient intake, physical activity, blood lipids, obesity prevalence and body fat distribution on NIDDM male diabetics. General characteristics, physical activity and exercise levels of subjects were invesigated by interviewing, daily calorie and nutrient intake were measured by convenient method. The following anthropometric measurements were made on all participats : weight, height. Also waist and hip circumference were measured on 174 male diabetics to get waist-to-hip circumference ratio as index of the body fat distribution. For measurement of plasma lipids, 12-hour fasting blood samples were drawn The results of this study were summarized as follows : 1. At the onset of diabetes, the major self-diagnosed symptoms were polydipsia, fatigue, and body weight redution 2. The average of daily energy intake of male diabetics was 2106 Kcal which is 96% of the RDA Percentage of energy is that carbohydrate:protein : pat=70:14:16. 3. Among the NIDDM male subjects, 59% was exercise regularly. 4. Obese subjects above in the ideal body weight of 120% are presently 17%, but 39% of subjects were reported to be obese in the past. The mean BMI of the male NIDDM diabetics is 23.3${\pm}$2.6 and the past mean BMI was 25.2${\pm}$2.7 The mean WHR was 0.93${\pm}$0.10. 5. When diabetics were divided into obese and nonobese group according to RBW, energy intake, blood pressure, blood glucose and total cholesterol were not significantly different between the two groups, but LDL and VLDL-cholesterol were significantly higher in the obese group. 6. RBW did not correlate with cholesterol and triglyceride, but WHR correlated significantly with cholesterol and triglyceride. In conclusion, these results from a present study support previous findings indicating that not only the degree of obesity but also the localization of fat is a risk factor for diabetes.

• Composites Research
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• v.24 no.6
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• pp.12-17
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• 2011

Interfacial durability and electrical properties of CNT or ITO coated PVDF nanocomposites were investigated for self-sensor and micro actuator applications. Electrical resistivity of nanocomposites for the durability on interfacial adhesion was measured using four points method via fatigue test under cyclic loading. CNT/PVDF nanocomposite exhibited lower electrical resistivity and good self-sensing performance due to inherent electrical property. Durability on the interfacial adhesion was good for both CNT and ITO/PVDF nanocomposites. With static contact angle measurement, surface energy, work of adhesion, and spreading coefficient between either CNT or ITO and PVDF were obtained to verify the correlation with interfacial adhesion durability. The optimum actuation performance of CNT or ITO coated PVDF specimen was measured by the displacement change using laser displacement sensor with changing frequency and voltage. The displacement of actuated nanocomposites decreased with increasing frequency, whereas the displacement increased with voltage increment. Due to nanostructure and inherent electrical properties, CNT/PVDF nanocomposite exhibited better performance as self-sensor and micro actuator than ITO/PVDF case.

• Journal of the Ergonomics Society of Korea
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• v.33 no.1
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• pp.59-68
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• 2014

Objective: The aim of this study is to investigate the effect of BackJoy on how it effectively reduces the physical load generated in a posture in which the user sits, increases user's comfort and satisfaction, and maintains the correct posture. Background: Because of development of science and economic development, most office workers and students spend about 75% of their working time in chairs. However most of them have a poor posture. Method: This experiment conducted measurement using a pressure mat and surveyed to evaluate fatigue level, satisfaction and comfort of sit. The study is experimented 20 male and 14 female participants. The participants carried out four different types of tasks and each task took 20 minutes long. Results: In the case of experiment results before and after the use of BackJoy, average pressure, contact area and pressure per unit area appear to prove that using BackJoy is more effective. Conclusion: Through this study, the BackJoy's effects for the maintenance of good posture and loads that occur in the body are reduced. In the future study, there are some researches needed for various verifications using an EMG sensor that shows loads of vertebrae and we need to analyze each group of the participants by dividing them. Application: The evaluation method used in this study can be applied to evaluating ergonomic chairs.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.2
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• pp.13-21
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• 1999

Flip chip assembly directly on organic boards offers miniaturization of package size as well as reduction in interconnection distances resulting in a high performance and cost-competitive Packaging method. This paper describes the investigation of alternative low cost flip-chip mounting processes using electroless Ni/Au bump and anisotropic conductive adhesives/films as an interconnection material on organic boards such as FR-4. As bumps for flip chip, electroless Ni/Au plating was performed and characterized in mechanical and metallurgical point of view. Effect of annealing on Ni bump characteristics informed that the formation of crystalline nickel with $Ni_3$P precipitation above $300^{\circ}C$ causes an increase of hardness and an increase of the intrinsic stress resulting in a reliability limitation. As an interconnection material, modified ACFs composed of nickel conductive fillers for electrical conductor and non-conductive inorganic fillers for modification of film properties such as coefficient of thermal expansion(CTE) and tensile strength were formulated for improved electrical and mechanical properties of ACF interconnection. The thermal fatigue life of ACA/F flip chip on organic board limited by the thermal expansion mismatch between the chip and the board could be increased by a modified ACA/F. Three ACF materials with different CTE values were prepared and bonded between Si chip and FR-4 board for the thermal strain measurement using moire interferometry. The thermal strain of ACF interconnection layer induced by temperature excursion of $80^{\circ}C$ was decreased with decreasing CTEs of ACF materials.

• Korean Journal of Oriental Medicine
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• v.16 no.1
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• pp.149-155
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• 2010

Objective : Ssangwha-tang is a traditional medicine formula widely prescribed for a decrease of fatigue after an illness in Korea. The aim of this study is to investigate the effect of Ssangwha-tang fermented by Lactobacillus fermentum (SF) on osteoclast differentiation in vitro and on bone metabolism of an ovariectomized rat in vivo. Methods : Tartrate-resistant acid phosphatase activity and staining were applied to evaluate the formation of osteoclasts. Ovariectomized rats were orally administrated with SF (30 ml/kg/day) for 12 weeks. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, triglyceride, phosphate, calcium levels were determined. Effect of SF on bone loss were studied by histological analysis and the measurement of bone mineral density. Results : SF significantly inhibited tartrate-resistant acid phosphatase activity and formation of osteoclasts in RAW264.7 cells stimulated by receptor activator for nuclear factor ${\kappa}B$ (NF-${\kappa}B$) ligand (RANKL). In addition, SF significantly decreased the level of triglyceride and increased the level of low-density lipoprotein. Moreover, the decrease of trabeculae of the femur was partially prevented in ovariectomized rats administrated with SF. Conclusions : SF treatment could prevent ovariectomy induced bone loss and its effects could be medicated by the inhibition of osteoclastogenesis.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.49-59
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• 2012

Although 3D stereoscopic movies had been paid attention to a few times since the 1900's, the interest had not been last. Most researchers pointed out the reason came from human factors because the early in the 3D technology growth had to develop technological possibility to realize 3D videos and ignore the importance viewers' perspective. In the 2D video research, many studies have explored the factors which make people got immersed or involved and felt visual fatigue, but they have not been the main issues in the 3D research until now. The present research believes human factor issue is one of the most important parts to accelerate 3D industry and thus, we try to make reliable and valid assessments to evaluate 3D video which are perceived characteristics, impression, and presence.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.1
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• pp.1-8
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• 2019

Motion sickness is dizziness symptom that occurs when movement detected in the vestibular organ and movement detected visually are collide with each other. When dizziness occurs, user complains of symptoms such as nausea and vomiting, sense of direction abnormality, and fatigue. These causes of dizziness are various and difficult to differentiate and treat the symptoms. Especially, among the types of dizziness VIMS(Visually Induced Motion Sickness) is a problem to solve in developing VR industry. These VIMS analysis can be done through user's vital signs measurement and feature analysis, and EEG characteristics analysis. Therefore, this paper is discuss the minimization of motion sickness caused by visual information based on EEG signal and present research trends related to it.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.729-736
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• 2017

In this study, the physics-based model and machine learning technique were used to conduct model-assisted probability of detection (MAPOD) experiments. The possibility of using in-service cracked parts was also investigated. Bolt hole shaped specimens with fatigue crack on the hole surface were inspected using eddy current inspection. Owing to MAPOD, the number of experimental factors decreased significantly. The uncertainty in the crack length measurement for in-service cracked parts was considered by the application of Monte Carlo simulation.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1123-1134
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• 2020

The goal of this study was to develop an accelerated life test for an implement working pump for an agricultural tractor. The field experiments were conducted to measure the load of an implement working pump during major agricultural operations such as plow tillage, rotary tillage, baler operations, and wrapping operations. The measurement system for an implement working pump load was constructed using a pressure sensor, the engine rotational speed, and the hitch pump displacement. The measured implement working pump load was calculated as an equivalent load for each agricultural operation using the Palmgren-Miner rule, which is a cumulative damage method. The equivalent load was calculated using the total load data and peak load data when the total data included the operation of an implement working. The annual usage time of the agricultural tractor was applied to develop two integrated equivalent loads. The acceleration factor was calculated to develop an accelerated life test and was calculated from the two integrated equivalent loads, the maximum pressure, and the flow rate conditions of the hitch pump. In Korea, the warranty life of a tractor is 2,736 hours, and the time required for the test to guarantee the operational life of tractors was calculated as 7,561 hours. The acceleration factors were calculated as 453.6 and 38.3, respectively, from the total load data and peak load data. The fatigue test time can be shortened by 16.7 and 197.4 hours according to the result of the acceleration factors.