• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.175-182
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• 2015

Objective : The purpose of this study was to investigate difference in fascicle behavior of the medial gastrocnemius during the locomotion with varying intensities, such as gait and one-legged and two-legged vertical jumping. Methods : Six subjects (3 males and 3 females; age: $27.2{\pm}1.6yrs.$, body mass: $62.8{\pm}9.8kg$, height: $169.6{\pm}8.5cm$) performed normal gait (G) at preferred speed and maximum vertical jumping with one (OJ) and two (TJ) legs. While subjects were performing the given tasks, the hip, knee and ankle joint motion and ground reaction force was monitored using a 8-infrared camera motion analysis system with two forceplates. Simultaneously, electromyography of the triceps surae muscles, and the fascicle length of the medial gastrocnemius were recorded using a real-time ultrasound imaging machine. Results : Comparing to gait, the kinematic and kinetic parameters of TJ and OJ were found to be significantly different. Along with those parameters, change in the medial gastrocnemius (MG) muscle-tendon complex (MTC) length ($50.57{\pm}6.20mm$ for TJ and $44.14{\pm}5.39mm$ for OJ) and changes in the fascicle length of the MG ($18.97{\pm}3.58mm$ for TJ and $20.31{\pm}4.59mm$ for OJ) were observed. Although the total excursion of the MTC and the MG fascicle length during the two types of jump were not significantly different, however the pattern of length changes were found to be different. For TJ, the fascicle length maintained isometric longer during the propulsive phase than OJ. Conclusion : One-legged and two-legged vertical jumping use different muscle-tendon interaction strategies.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.183-190
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• 2015

Objective : Walking with a Material handling is an activity frequently undertaken by agricultural workers in Korea, due to the nature of their work. This study aimed to investigate differences in biomechanical variables according to the mechanical alignment of the lower limbs when walking with a heavy load, and to use this as basic data in the design of various working environments to reduce the skeletomuscular burden on the knee joint. Method : The study subjects comprised of 22 right-foot dominant adult men and women aged between 20 and 23 years. The subjects were divided into a varus or valgus group according to the mechanical alignment of the lower limb by using radiographic findings. The subjects walked without any load and with a load of 10%, 20%, or 30% of their body weight held in front of them. The Kwon3d XP program was used to calculate biomechanical variables. Results : The flexion/extension moment of the knee joint showed a decreasing trend with increased load, irrespective of the mechanical alignment of the lower limb, while the varus group did not show normal compensatory action when supported by one leg at the point of maximum vertical ground reaction force. In addition, in terms of the time taken, subjects showed no difficulties in one-foot support time up to 20%/BW, but at 30%/BW, despite individual differences, there was an increase in single limb. The increased load resulted in a decrease in the ratio of standing phase to ensure physical stability. The valgus group showed a trend of increasing the stability of their center of mass with increasing load, through higher braking power in the early standing phase. Conclusion : In conclusion, although there was no statistical difference in biomechanical variables according to the mechanical alignment of the lower limbs, the varus group showed a more irregular walking pattern with a Material handling than the valgus group, partially proving the association between lower limb alignment and walking with a Material handling.

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.670-678
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• 2003

Recently, since industrial waste and life waste leaped into a pollution source, the building material used now a days is striking the limit. The purpose of this paper is to investigate an application of recycled coal ash using non-sintering method in the construction field. Accordingly, compressive strength, elastic modulus and drying shrinkage were experimentally studied for hardened coal ash using the non-sintering method. Also, Lineweaver and Burk method were applied to the regression analysis of drying shrinkage for the proposal equation. Elastic modulus, compressive strength of material become the basis properties of structural design. And these properties by age for hardened coal ash are important because of change by pozzolan reaction. This hardened coal ash is weak for tensile stress like that of concrete. And drying shrinkage is very important factor to make huge tensile force in early age. In the results, although some differences were shown when comparing coal ash with mortar or concrete, the application as a building material turned out to be possible if further researches were carried out. And the shrinkage characteristic of hardened coal-ash reveals to be similar to that of moderate heat cement.

• Journal of Preventive Medicine and Public Health
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• v.38 no.3
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• pp.291-297
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• 2005

Objectives : The effects of exercise on bone density have been found to be inconsistent in previous studies. We conducted a cross-sectional study in premenarcheal girls to test two hypotheses to explain these inconsistencies. Firstly,'the intensity of mechanical strain, in terms of the ground reaction force(GRF), has more important effects on the bone mass at a weight-bearing site', and secondly, 'calcium intake modifies the bone response to exercise'. Methods : The areal bone mineral density was measured at the Os calcis, using peripheral dual energy X-ray absorptiometry, in 91 premenarcheal girls aged between 9 and 12 years. The intensity of mechanical strain of exercise was assessed by a self-report questionnaire and scored by the GRF as multiples of body weight, irrespective of the frequency and duration of exercise. The energy and calcium intake were calculated from the 24-hour dietary recall. An analysis of covariance(ANCOVA) was used to determine the interaction and main effects of exercise and calcium on the bone density, after adjusting for age, weight, height and energy intake. Results : The difference in the bone density between moderate and low impact exercise was more pronounced in the high than low calcium intake group. The bone density for moderate impact exercise and high calcium intake was significantly higher than that for low impact exercise (p=0.046) and low calcium intake, after adjusting for age, weight, height and energy intake. Conclusions : Our study suggests that the bone density at a weight-bearing site is positively related to the intensity of mechanical loading exercise, and the calcium intake may modify the bone response to exercise at the loaded site in premenarcheal girls.

• Journal of the Korean Society of Food Culture
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• v.13 no.4
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• pp.261-266
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• 1998

In an attempt to evaluate the effects of alkali agents on properties of Ramyon, cooking quality, textural and sensory properties were examined. The shear extrusion force of Ramyon made from sample A(potassium carbonate 64%, sodium carbonate 14%, sodium pyrophosphate 2% and sodium metaphosphate 20%), sample B(potassium carbonate 31%, sodium carbonate 39% , sodium pyrophosphate 1%, sodium metaphosphate 15%, sodium polyphosphate 8%, sodium phosphate monobasic 4% and sodium phosphate dibasic 2%), sample C(potassium carbonate 60%, sodium carbonate 33% and sodium pyrophosphate 7%), and sample D(potassium carbonate 44%, sodium carbonate 27%, sodium metaphosphate 27% and sodium polyphosphate 2%) were 12.80(kgf), 10.35(kgf), 9.05(kgf) and 8.45(kgf), respectively, but that of control I was 5.24(kgf). The hardness of Ramyon manufactured with sample A, B, C and D were 18.57(kgf), 16.48(kgf), 14.26(kgf) and 12.34(kgf), respectively, but that of control I was 11.23(kgf). At cooking quality examination of Ramyon made from several alkali agents, weight of cooked Ramyon was increased but volume was appeared in vice versa. Extraction amounts of Ramyon manufactured with several alkali agents during cooking were from 35% to 38%, but that of control I was 70%. These changes will provided many advantages in the preparation of Ramyon. The $I_2$ reaction value(${\alpha}-degree$ of noodle) of Ramyon manufactured with several alkali agents and control were shown to almost same values, from 2.10 to 2.20. Sensory properties of cooked Ramyon which was manufactured with several alkali agents showed quite acceptable.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.61-74
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• 1998

The Purpose of this study was to investigate the stress distribution and tooth displacement at the initial phase produced by 5 types of molar uprighting springs using finite element method. The three dimensional finite element model of lower dentition, bone and springs was composed of 5083 elements and 2071 nodes. The results were as follows: 1. In case of helical spring and root spring, intrusion of lower canine and first premolar were observed md distal tipping, translation and extrusion of lower second molar were observed. 2. In case of T-loop, modified T-loop and box loop, intrusion and distal translation of lower second premolar were observed, and the largest crown distal tipping and translation of lower second molar were observed in T-loop and the smallest were observed in box loop. 3. In case of T-loop with cinch-bact crown distal tipping and translation of lower second molar were decreased, but extrusion was also decreased. 4. With increase of activation in T-loop, mesial translation and won distal tipping of lower second molar were increased and edentulous space was closing, but distal translation of second premolar was also increased. 5. With increase of tip-back bend in T--loop, distal tipping and translation of lower second molar were increased, but extrusion was also increased more largely.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.191-203
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• 2009

The effect of stabilizing piles on cut slopes is checked and the behavior of slope soil and piles are observed throughout the year by field measurements on the large-scale cut slopes. First of all, the behavior of the slope soil was measured by inclinometers during slope modification. Landslides occurred in this area due to the soil cutting for slope modification. The horizontal deformations of slope soil are gradually increased and rapidly decreased at depth of sliding surface. As the result of measuring deformation, the depth of sliding surface below the ground surface can be known. Based on the measuring the depth of the sliding surface, some earth retention system including stabilizing piles were designed and constructed in this slope. To check the stability of the reinforced slope using stabilizing piles, an instrumentation system was installed. As the result of instrumentation, the maximum deflection of piles is measured at the pile head. It is noted that the piles deform like deflection on a cantilever beam. The maximum bending stress of piles is measured at the soil layer. The pile above the soil layer is subjected to lateral earth pressure due to driving force of the slope, while pile below soil layer is subjected to subgrade reaction against pile deflection. The deflection of piles is increased during cutting slope in front of piles for the construction of soil nailing. As a result of research, the effect and applicability of stabilizing piles in large-scale cut slopes could be confirmed sufficiently.

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.598-617
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• 2020

In many enterprises, the extent and the frequency of damages incurred due to the unethical behavior of the members of the organization have not reduced, but rather the magnitude and frequency of damages have been increasing. Research at an organizational level is necessary at this point in time, to investigate the contributing variables that cause this unethical behavior, the measures to manage them, and the control variables that can reduce unethical pro-organizational behavior. Therefore, this study seeks to explore perceived organizational support and psychological entitlement as leading factors of unethical pro-organizational behavior, based on the theory of social exchange, and to examine the reaction mechanism between these variables. This is particularly because a large number of the current labor force belongs to the millennial generation (born after 1978) or Generation Y, and their sense of psychological entitlement has been problematic in their organization. The effect of perceived organizational support on unethical pro-organizational behavior and the effect of psychological entitlement on unethical pro-organizational behavior were examined through a review of existing literature, and an empirical analysis was conducted to investigate the moderating effects of psychological entitlement on perceived organizational support and unethical pro-organizational behavior. A regression analysis was conducted based on the valid data of 185 members of an organization who belong to the millennial generation, and the analysis results showed that a sense of psychological entitlement had a moderating effect between perceived organizational support and unethical pro-organizational behavior. Based on these findings, this paper proposes theoretical and practical implications for unethical pro-organizational behavior and psychological entitlement, and hopes to contribute to expanding research in this area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.263-274
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• 2018

In this study, the applicability and external/internal stability of a MSEW abutment with a slab were investigated. Structural analysis of slab bridges between 10 ~ 20.0 m and thicknesses of 0.7 ~ 0.9 m was carried out to calculate the reaction forces due to dead and live loads acting on the bridge supports. The slab bridge with a length of 20.0 m satisfied the allowable contact pressure of 200 kPa for the true MSEW abutment. Because the external stability of the true MSEW abutment was dominated by the geometry of the MSE wall, the change in the factor of safety due to the load of the super-structure is small. Because the stiffness of the foundations is fixed and the load of the super-structure is increased, the factor of safety of the bearing capacity was reduced. As the load of the super-structure was increased, the horizontal earth pressure of the true MSEW abutment increased greatly. As a result, the pullout and fracture of the uppermost reinforcement, which are the factors of safety, did not meet the design criteria. Therefore, it is necessary to increase the pullout resistance and the long-term allowable tensile force of the reinforcement placed on the top of the reinforced soils to ensure efficient design and performance of a true MSEW abutment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6610-6617
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• 2013

This study examined the current and future Indoor Air Quality (IAQ) control device markets and analyzed the recent studies on indoor air pollutantr emoval to develop a new technology for fine dust control. Currently, the mechanical filter technique occupies the bulk of the IAQ control market but the electronic technique is emerging as an alternative to control fine dust efficiently. Among the gaseous VOCs and fine dust particles contaminating the indoor air quality, fine dust particles are more problematic because they threaten human health by penetrating deep into the body and producing secondary contaminants by chemical reaction with VOCs. The electronic IAQ control device using dielectrophoretic and electrostatic forces is a good option for public spaces where many people pass, and at the same time, it needs to consider temperature, humidity, and the particle properties of specific areas to highlight the control efficiency. Electronic-related technology is expected to be used widely in many public/private spaces wherever a dust-free environment is required.