• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.625-629
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• 1997

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindele. Current work was emphased on the investigation of air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal,ari jet was injected against through the leakage flow. It has a combined geometry of a protective collar type and an air jet type. In this study, both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measureements are carried out of verify sealing improvement. But of the turbulence and the compressible flow model were introduced in CFD analysis. The sealing effect of the leakage clearance and the air jet magnitude were studied for variousparameter in the experiment. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effects of sealing improvement are explained as decreasing of effective leckage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance become larger.

• KSTLE International Journal
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• v.3 no.2
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• pp.79-83
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• 2002

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindle requires non-contact type of sealing mechanism. Current work emphases on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet was injected against through the leakage flow, It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement The sealing effects of the leakage clearance and the air jet magnitude are studied in various parameters. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient Effect of sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.

• International Journal of Contents
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• v.13 no.3
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• pp.59-64
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• 2017

The purpose of this study is to identify the types of injuries and the protective behaviors of soccer club members to prevent injuries, and promote health. Data was collected from 395 soccer club members from thirteen football clubs in Seoul and Gyeonggi province using question tool developed by researchers. Data analysis was performed using SPSS 23 for descriptive analysis and Chi-square test. The results showed that sport for soccer injuries was serious and medical expenses was significant. The demographic information showed that 50-year-old and over adults were vulnerable and had a disproportionate number of injuries. Those employees who helded administrative positions, white-collar and specialized jobs also experienced the high level of injury experience. Despite this many injuries, many respondents appeared to be lacking a protective actions, such as not wearing protective gear. It was critical for the club members to improve their knowledge and awareness of safe sports activities.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.76-82
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• 1998

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. Current work is emphasized on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet is injected against through the leakage flow. It has a combined geometry of a protective collar type and an air jet type. In this study, both of a numerical analysis by CFD(Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. Both of the turbulence and the compressible flow model are introduced in CFD analysis. The sealing effect of the leakage clearance and the air jet magnitude are studied for various parameter in the experiment. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effects of sealing improvement are explained as decreasing of effective leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.

• Journal of the Korean Society of Costume
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• v.57 no.8
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• pp.14-23
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• 2007

The purpose of this study was to investigate the present condition of cold protective clothing for mailman, to improve its design in movement, fitness, and other functions, and supply basic data for its performance evaluation. The results are as follows : The 46.60% of those questioned did not satisfy current clod protective clothing fer mailman. Especially, they considered dissatisfactory in properties such as waterproof, comfort, activity, and sweat absorption. The newly developed cold protective clothing is two-piece style composed of jacket and pants. Both jacket and pants are composed of inner and outer clothing individually. In both jacket and pants, their outer clothing's material was waterproof, windproof, and breathable shell fabric on which PTFE film laminated and their inner clothing's material was 100% polyester Polar polis to have better insulation property. The jacket has attachable cap which can be used as rain gear and set-in sleeve with stand collar. It also had big outside patch pockets and side seam pockets to ensure enough storage space. The pants have knee pads to give free movement to knees and slant side pockets. Inner clothing of both jacket and pants can be worn during working inside without out clothing. Insulation of the newly developed cold protective clothing was not better than current one except right hand, left hand and left foo. It is considered that is because thickness of material is the most important factor to influence insulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2159-2166
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• 2000

Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger

• Tribology and Lubricants
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• v.13 no.3
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• pp.56-62
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• 1997

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindles require non-contact type sealing mechanism. In this study, an optimum seal design to minimize leakage is concerned in the aspect of flow control. This paper categorizes geometries of mostly used non-contact type seals and analyzes each leakage characteristics to minimize a leakage on sealing area. Effect of minimum clearance and its position are considered according to variation of detail geometry. The estimation of non-leaking property is determined by amount of pressure drop in the leakage path assuming constant leakage flow. To simulate an oil jet or oil mist type high speed spindle lubrication, the working fluid is regarded as two phases that are mixed flow of oil phase and air phase. Both of the turbulence and the compressible flow model were introduced in CFD(Computational Fluid Dynamics) analysis. Design parameters has been induced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.679-686
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• 2023

According to the PSPC (Performance Standard for Protective coatings) rule, the edge preparation must keep 2R or 3-pass grinding. The stiffener plate edge grinding of the ship inside is manually progressed by worker and worked with just one pass grinding. In addition, the poor working condition cause grinding workers to avoid working in them, and the quality is determined by the skill-level of a worker. This research developed optimal tool for edge milling. In order to milling various collar plates edge, this research developed vision system that can recognize the edge points and it developed a program that operator can adjust the amount of cutting and speed, and add various features so that milling quality would be improved. So, this research focused on overcoming the difficulties in working condition and development of automated milling machine for ship stiffener plate.

• Fashion & Textile Research Journal
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• v.13 no.5
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• pp.759-768
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• 2011

This study is designed to understand current wearing conditions of air force mechanic parkas and evaluate their functionality by examining the wearing conditions and wearers' subjective assessment. By doing so, it also intends to identify issues that require improvements; and to provide basic data for future development of air force mechanic parkas. A survey was conducted as a study methodology, and the collected 1,628 questionnaires were analyzed. Findings of this study are as follows. 1. In the usability assessment, it was found that visibility of body sides was needed to be enhanced since reflective tapes were attached only to the front and back of the body; pockets were too big, but not convenient to keep mechanic tools; the design of hiding hood was not suitable for water-proof clothing; and a new design of size-controllable hood was called for since the hood blocked eye sight. With respect to the fabric, dissatisfaction was identified with durability, cold-proof and fire-proof features. 2. In the mobility assessment, respondents showed low satisfaction with collar heights and neck girths. Mobility score was over moderate level on average, except the parka length that obstructs wearers' movement, and neck and collar size. 3. In the wearability assessment, respondents presented moderate satisfaction with pleasantness, weight, pressure and dampness. However, insulation was found unsatisfactory. Based on the result, this study proposed improvement plans on design, pattern and fabric; and is expected to serve as basic data for developing more effective and functional air force mechanic parkas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.122-130
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• 2018

The International Maritime Organization has enacted mandatory performance standards for protective coatings (PSPC), and as a result, shipyards must perform 2R or 3-pass milling on the edges of color plates. However, manual milling could result in many problems in terms of work environment and productivity. Therefore, it is necessary to develop an edge milling automation system that can satisfy the regulations. In this study, a basic design for an edge milling automation system was developed for standard color plates, and the machining process was established by applying shape recognition and a machining path generation algorithm. In addition, operating software was developed, and suitable milling conditions were derived based on the results of a milling test. The results could be used to build an automation system that meets the PSPC requirements and improve productivity.