• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.98-104
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• 2022

When processing parts, the cutting oil can improve the cooling performance of the workpiece and tool to increase the precision of the workpiece or extend the life of the tool and facilitate chip extraction. Since such cutting oil has a harmful effect on the environment and the human body due to additives such as sulfur, research on a minimum lubrication supply method using an eco-friendly oil is recently underway. The minimum lubrication supply method minimizes the amount of cutting oil used during processing and processes it, which can reduce the amount of cutting oil used, but has a problem in that cooling performance efficiency is poor. Therefore, this study conducted a study on mist cooling of lubricants to reduce the amount of cutting oil used and maximize the cooling effect of processing heat generated during tapping processing. Spray pressure, processing speed, direction, and lubricant spray amount, which are considered to have an effect on cooling performance, were set as process conditions, and the effect on temperature was analyzed by performing an experiment using the box benquin method among experiments were analyzed. Through the experimental analysis results, the optimal conditions for mist and processing that maximize the cooling effect were derived, and the validity of the results derived through additional experiments was verified. In the case of processing by applying the mist lubrication method verified through this study, it is considered that high-precision processing is possible by improving the cooling effect.

• KIEE International Transactions on Electrophysics and Applications
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• v.12C no.4
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• pp.229-235
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• 2002

The apparent volume resistivity of powders measured by both the tapping and the compressing methods was compared in this study. Factors such as applied voltage, pressure, corona charging, and so on affecting the apparent volume resistivity of polymer powders were also examined experimentally. Powders of polyacrylonitrile and Nylon 11 were mainly used. The values of the apparent resistivity of polymer powders taken by the tapping method turned out to be larger than those taken by the compressing method, which indicates that the apparent volume resistivity of polymer powders depends strongly on the measurement method. The apparent resistivity of polymer powders increased with an increase in applied voltage while it decreased with an increase in pressure, tapping time, and particle size. The influence of the moisture content of powder and corona charging on the resistivity of polymer powders is also discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.105-111
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• 2012

High speed machining is the core technology that influences the performance of machine tools, and the high speed motor spindle is widely used for the high speed machine tools. The important problem in high speed spindle is to minimize the thermal effect by motor and bearing and frequency effect. This paper presents the thermal characteristic analysis and frequency experiment for a high speed spindle considering the flow rate of cooling oil. A high speed spindle is composed of angular contact ceramic ball bearings, high speed built-in motor, oil cooling jacket and so on. The thermal analyses of high speed spindle need to minimize the thermal effect and maximize the cooling effect and they are carried out under the various cooling conditions. Heat generations of the bearing and the high speed motor are estimated from the theoretical and experimental data. To find out the characteristic of vibration, the high speed spindle is excited in operational range. This result can be applied to the design and manufacture of a high speed tapping spindle.

• Journal of Sensor Science and Technology
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• v.21 no.1
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• pp.75-81
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• 2012

Optimizing the tapping time of a blast furnace is important to a stable operation and life extension. To optimize the tapping time of the blast furnace, the location of Hearth Liquid Level should be recognized. There are several ways to measure the hearth liquid level in the blast furnace, such as Electromotive Force(EMF) measurement, pressure measurement by putting in nitrogen probe and manometry with strain gauge. In this paper, it will be discussed using strain gauge among the three methods. Conventional strain gauge must be revised periodically. Since, internal pressure, temperature of internal refractory material and wind pressure have effect on the strain gauge. However, static pressure value is required to compensate. To solve these problems, this paper suggests finding relationship between Hearth Liquid Level and strain gauge output, adding digital filter in strain gauge. Using the proposed method, it was possible to estimate the hearth liquid level and determine the appropriate tapping time. Usefulness of the proposed method through simulations and experimental results are confirmed.

• Korean Journal of Plant Resources
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• v.11 no.1
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• pp.70-79
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• 1998

This study was conducted to understand the effects of weather and tapping date on yield and quality of lactree(Rhus verniciflua) sap yield showed a significant positive correlation with the minimum temperature of one day before sap collection at 1% level and with theminimum humidity of theday of sap collection at 5% level. However, the differences between the maximum and the minimum temperatures and humidities of the day of sap collection were negatively correlated with the sap yield at 5% level. Multiple regression analysis indicated that the minimum temperature of one day bofore sap collection and the minumum humidity of the day sap collection were important factors for increasing sap yield. The high sap yield of lactree by Japanese tapping method was recorded during mid-July and early August. Seasonal variation in lactree sap constituents was observed. The sap collected on 15th of August contained the highest urushiol content (68.3%) and the lowest water content resulting in high quality of lactree sap. By reversed-phase HPLC analysis, fove urushiol components were separated from each other depending on the number of doulbe bonds in the side-chain , and seaxonal variation of urushiol composition was noticed. The 3-C15 triene content fo the sap collected on 5th of July was the highest(77.56%) indicating the major component of urushiol which affects lactree sap quality.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.192-195
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• 2003

There has been increasing interest in the applications of synthesized molecules of nanometer scale in recent years due to their potential utilization in various fields such as biology, optoelectronics and molecular electronics. In this study, the terpyridine-platinum (II) complex on the periphery of the dendritic carbosilane has been prepared from the reaction of Pt(COD)Cl2 and the 4'-functionalized-(2,2':6',2"-terpyridine) on dendrimers. The self-assembly process was carried out to obtain indivially dispersed dendrimer on Au (111) substrate. It was found that STM was unsuitable to obtain a obvious image of dendrimers. Tapping-mode atomic force microscopy(AFM) has been used to investigate the shape and size of dendrimers individually dispersed on Au (111)substrate. As a result, the imaged single dendrimer show that dendrimer is dome shaped and its size can be measured by tapping-mode AFM.

• Steel and Composite Structures
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• v.42 no.3
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• pp.315-323
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• 2022

Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self-tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.2
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• pp.165-172
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• 2021

Purpose : This study was conducted to find out the effect on the activity of trunk and lower limbs muscles during abdominal drawing-in bridging exercises by verbal cue on the unstable supporting surface after pelvic rearward sloping taping for trunk stabilization movement. Methods : The study subjects were recruited by using the on-campus bulletin boards for healthy adult males and females in their 20s attending K University in Changwon-city, South Gyeongsang Province. The subjects were 30 persons (15 males and 15 females) who agreed to the study purpose in accordance with the criteria for selection and exclusion. Results : The results were obtained by measuring the muscle activity of the trunk and lower limbs during abdominal drawing-in bridging exercises by verbal cue on the unstable supporting surface after pelvic fixed tapping. The effects on erector spinae and hamstring muscles was statistically significantly lower (p<.05), it was confirmed that there were no statistically significant differences between the multifidus and gluteus maximus muscle (p>.05). Conclusion : Through this study, it was found that the excessive flexion of the waist was significantly reduced from erector spinalis and hamstring muscle after abdominal drawing-in bridging exercises by verbal cue on the unstable supporting surface after pelvic rearward sloping tapping compared to the general bridging exercises.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.692-707
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• 1998

Aim. A neurobehavioral test for workers exposed to organic solvents in the workplace can be affected by many factors : age, education, motivation, ethnicity, etc. To apply more suitable neurobehavioral test for Korean workers, we evaluated the validity of several items of computerized and traditional neurobehavioral tests. Methods. We have applied eleven tests : four items of computerized neurobehavioral test(Swedish Performance Evaluation System) including Addition, Symbol-Digit, Dig-it Span, and Finger tapping speed, and seven items of traditional neurobehavioral test consisting of Addition, Digit-Symbol, Digit Span, Benton visual retention test, Pursuit aiming, Pegboard, and Tapping. These tests were performed on 96 workers exposed to solvents, and 100 reference workers. The concurrent and construct validities were evaluated by group difference, correlation with age, educational level, hippuric acid level, neurotoxic symptom, current exposure level, multitrait-multimethod matrix, fator analysis, and discriminant analysis. Results. Statistically significant differences were observed between the workers exposed to solvents and referents in computerized Symbol-Digit, Finger tapping speed, traditional Digit-Symbol and Pegboard. The computerized Symbol-Digit, traditional Digit-Symbol, Addition, Benton visual retention test, and Pegboard were found to be related to the age. The performance of computerized Symbol-Digit, Addition, and traditional Digit-Symbol were found to be related to the educational level significantly. The computerized Symbol-Digit, Finger tapping speed, and traditional Digit-Symbol were found to be related to hippuric acid, and neurotoxic symptom. The discriminability of Finger tapping speed, and Pegboard was better than the other tests. In discriminant analysis, the model with two variables, the computerized Symbol-Digit and Pegboard, classified almost 70 percent of the workers correctly. Conclusions. These results suggest that the computerized Symbol-Digit, Finger tapping speed, and Pegboard are more satisfactory for our purpose, and the Addition, Tapping, Benton visual retention test, and Pursuit aiming are less valid than other items. These may allow the reasonable selection of core neurobehavioral tests for workers exposed to solvents in Korea.

• The Journal of the Korean dental association
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• v.32 no.4 s.299
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• pp.278-278
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• 1994