• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.170-178
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• 2000

Most of manufacturers try to produce the most efficient filter for respirators with the lowest breathing resistance. Filter performance depends on low penetration, i.e., high efficiency (%), and low pressure drop ($mmH_2O$). This study was performed to evaluate performance of respirator filters by quality factor ($q_F$) and suggest the direction for improvement of respirator filters of good quality in Korea. Two mechanical filters, S and K made in Korea, three filtering facepieces, S made in China, C made in Korea and M made in USA, which were widely used in the workplace, were selected and tested efficiency and pressure drop in accordance with flow rate, using with Automated Filter Tester Model 8110 (TSI, USA). The best quality factor within the same respirator filter categories was $0.0672cm^{-1}\;H_2O$ for mechanical filter S, $0.0698cm^{-1}\;H_2O$ for filtering facepiece M at flow rate of 32Lpm. Mechanical filter S would be the best suitable during heavy work since qulity factors decrease less sharply than any others as increased flow rates. It was necessary for mechanical filter S to lower pressure drop without increasing efficiency, but mechanical filter K should be increased efficiency and decreased pressure drop. While filtering facepiece M had the best quality performance of three ones, Sand C should get much higher efficiency and lower pressure for better performance.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.29-37
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• 2015

Objective : The purpose of this study was to investigate the biomechanical properties of shock absorption strategy and postural stability during the drop landing for each types. Methods : The motions were captured with Vicon Motion Capture System, with the fourteen infra-red cameras (100Hz) and synchronized with GRF(ground reaction force) data(1000Hz). Ten male soccer players performed a drop landing with single-leg and bi-legs on the 30cm height box. Dependent variables were the CoM trajectory and the Joint Moment. Statistical computations were performed using the paired t-test and ANOVA with Turkey HSD as post-hoc. Results : The dominant leg was confirmed to show a significant difference between the left leg and right leg as the inverted pendulum model during Drop Landing(Phase 1 & Phase 2). One-leg drop landing type had the higher CoM displacement, the peak of joint moment with the shock absorption than Bi-leg landing type. As a lower extremity joint kinetics analysis, the knee joint showed a function of shock absorption in the anterior-posterior, and the hip joint showed a function of the stability and shock absorption in the medial-lateral directions. Conclusion : These findings indicate that the instant equilibrium of posture balance(phase 1) was assessed by the passive phase as Class 1 leverage on the effect of the stability of shock absorption(phase 2) assessed by the active phase on the effect of Class 2 leverage. Application : This study shows that the cause of musculo-skeletal injuries estimated to be focused on the passive phase of landing and this findings could help the prevention of lower damage from loads involving landing related to the game of sports.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.360-368
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• 2010

The paper presents a case study from a surface mine where the controlled augmentation of throw and drop of the blasted muck piles was warranted to spread the muck piles on the lower berm of the bench. While the augmentation of throw increased the lateral spread and the looseness of the broken muck, the augmentation of drop significantly lowered the muck pile height for easy excavation by the excavators. In this light, the present paper highlights and discusses some pertinent changes in the blast design parameters for such specialized application of cast blasting in a surface mine, where a sandstone bench, with average height of 22-24 m was to be made amenable for excavation by 10 m3 rope shovels, which possessed maximum digging capability of up to 14 m. The results of tailoring the blast design parameters for augmentation of throw and drop are compared with the baseline blasts which were earlier practiced on the same bench by dividing the full height of the bench in 2-slices; upper slice (10-14 m high) and lower slice (12-15 m high). Results of fragment size, its distribution and total cycle time of excavator (shovel) are presented, and discussed.

• Journal of the Korean Society of Tobacco Science
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• v.26 no.2 s.52
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• pp.117-125
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• 2004

In this study, we have investigated the natural and puffing combustibility of cigarette brands and the compulsory ash-drop, and analysed factors related to the materials. Cigarette combustibility was greatly affected by the tobacco weight in cigarettes rod. Combustion rate of 4AOR cigarette made by flue-cured tobacco was 5.02 $^{mm}/_{min}\;and\;10\%$ faster than 1BO cigarette. Combustion pattern has interrelation with sugars, chlorine and ash contents among tobacco components. Combustion rate of 4DL, flue-cured tobacco was 55 seconds faster than 1CL tobacco extremely much in sugars contents, and ash drop was maintained at $21\%$ longer. Combustion time and burning rate were fast in cigarette made by expanded tobacco slice and tobacco stem and the formation of ash was poor. The length of puffed ash drop of expanded tobacco slice and tobacco stem were 18.6 mm and 25.2 mm and these forced ash drop length were 3.8 mm and 4.9 mm respectively. Puffed burning rate of general cigarette was $14.3\%$ faster than static burning rate and super slim type cigarettes was $21.3\%$ faster. Combustion rate and ash drop of domestic and foreign cigarette brands were quite different depending on tar level and cigarette types. The lower tar level, the faster combustion rate and the shorter ash drop.

• Journal of Fashion Business
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• v.10 no.3
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• pp.100-116
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• 2006

The purpose of this study was provide for the useful fundamental data by developing an lower appeal sizing system according to body types for early 20s Chinese women. The subjects were 348 women whose ages were between 19 and 24 to live in Beijing and Shanghai, China. Out of total, 341 women with no abnormal numbers were taken as the sample of research. This study was to characterize lower body type of the Chinese women in their early 20s by classifying them into groups according to drop measurement suggested by GB. This study investigated body types of the Chinese women in their early 20s depending upon regions (Beijing and Shanghai) according to each factor. This study made use of 46 kinds of indirect measures from June 23, 2004 to August 7, 2004. SPSS WIN 13.0 Program was used. And, correlation analysis, factor analysis, ANOVA(t-test and F-test) and duncan's multiple test, etc were done. The average of the early 20s Chinese women's stature is 160.0cm, waist circumference 66.4cm, hip circumference 89.8cm, weight 52.1kg. The result of analysis about the early 20s Chinese women's lower body size which are total 62 items come to 6 factors. The Chinese women in their early 20s were divided into 3 groups depending upon waist circumference and drops of hip circumference.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.481-488
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• 2021

This study aimed to identify and to compare the difference the changes of one-leg drop landing pattern depending on chronic ankle instability (CAI) among basketball club members. For 30 basketball club members who are currently participating in recreational basketball games in Busan Metropolitan City, 21 CAI groups and 9 CON groups were classified according to the CAI standards provided by the International Ankle Consortium. The one-leg drop landing pattern was measured with the alignment of the lower extremity and joint movement at the initial contact (IC), and the point of peak knee flexion. In addition, the one-leg drop landing pattern was tested with the muscular activity of tibialis anterior, peroneus longus, medial gastrocnemius and gluteus medius at the initial contact (IC), heel contact (HC), and the point of peak knee flexion. The results of this study showed that there was no significant difference in lower limb alignment and lower limb muscular activity among single leg drop landing. These results showed no significant differences in the one leg drop landing pattern and muscular activity depending on CAI. The further studies should classify the types of chronic ankle instability and consider the physical demands and movement characteristics depending on their playing position for providing useful information on prevention of CAI in basketball club members.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.30-37
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• 2008

The evaporation pressure drop of $CO_2$ (R-744) in horizontal tubes was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth, horizontal stainless steel tube of 7.75 and 4.57 mm inner diameter. The experiments were conducted at saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed the evaporation pressure drop of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. The pressure drop measured during the evaporation process of $CO_2$ increases with increased mass flux, and decreases as the saturation temperature increased. The evaporation pressure drop of $CO_2$ is very lower than that of R-22. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the correlation of Choi et al. But existing correlations failed to predict the evaporation pressure drop of $CO_2$. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation pressure drop of $CO_2$ in a horizontal tube.

• Physical Therapy Korea
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• v.29 no.4
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• pp.249-254
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• 2022

Background: The lateral step down (LSD) is a form of stair negotiation used by the elderly because it requires less movement of the lower extremity. Although it is necessary to study the amount of pelvic drop and the strength of a hip abductor during LSD for intervention, limited studies have investigated the relationship between the amount of pelvic drop and strength of a hip abductor during LSD in elderly people. Objects: This study aimed to determine the relationship between the amount of pelvic drop on an unsupported leg and the strength of the hip abductor during LSD in the elderly. Methods: Thirty elderly people (male: 17, female: 13) were recruited. Subjects performed the LSD task, and the evaluator measured and the amount of pelvic drop on an unsupported side. Also, the isometric strength of the hip abductor was measured in a supine position. Results: We found significant relationships between the strength of the hip abductor and the amount of pelvic drop (r = -0.386). The average hip abductor strength normalized by body weight was 1.06 N/kg (max: 1.99, min: 0.52) and the average contralateral pelvic drop (CPD) angle was 4.16° (max: 15.3, min: 0). Conclusion: Our results indicated that the strength of the hip abductor had a moderate correlation with the CPD during a LSD in the elderly. Hip abductor weakness could translate into altered movement of the pelvis.

• The Research Journal of the Costume Culture
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• v.20 no.4
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• pp.529-534
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• 2012

An analysis of adult women's somatotypes classified by drop values can provide important preliminary data in determining standard clothing sizes for mass production of ready-made clothes. This is because the values are based on measurements of girth, which is essential information in the size-setting process. Adult women's body types are classified according to drop values in a standard clothing size system adopted by Korea and several other countries. This study aims to identify somatotype characteristics of adult women aged 20 to 69 by using five types of drop values: bust-waist, hip-waist, hip-bust, abdomen-waist, and hip-abdomen. Statistical cluster analysis of collected data revealed four somatotypes among adult women. Type R, with a developed lower body, accounted for 36.6%, and its bodyline was found to be closest to the average adult woman. Type X, constituting 25.4%, had the curviest contours of all and relatively large hip measurements, with the thinnest figure. Flat abdomen and hips characterized type Y, which accounted for 18.9%. Lastly, 19.0% fell into type H, the most obese figure, in which abdomen girth exceeded hip measurements. Since type H has excess fat deposits in the abdomen, not only hip measurements but also abdomen girth should be considered when designing top longer than torso-length and bottoms.

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.332-335
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• 2020

Drop casting, a solution process, is a simple low-cost fabrication technique that does not waste material. In this study, we elucidate the effect of the concentration of a InGaZnO solution on the electrical properties of drop-cast oxide thin-film transistors. The higher the concentration the larger the amount of remnant InGaZnO solutes, which yields a thicker thin film. Accordingly, the electrical properties were strongly dependent on the concentration. At a high concentration of 0.3 M (or higher), a large current flowed but did not lead to switching characteristics. At a concentration lower than 0.01 M, switching characteristics were observed, but the mobility was small. In addition to a high mobility, sufficient switching characteristics were obtained at a concentration of 0.1 M owing to the appropriate thickness of the semiconductor layer. This study provides a technical basis for the low-cost fabrication of switching devices capable of driving a sensor array.