• Tribology and Lubricants
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• 제25권5호
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• pp.348-358
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• 2009

To satisfy the more severe emission regulation and the demand of higher fuel economy in near future, the combustion pressure and power output of engines is going to be higher. In order to get the reduction of engine emission and the higher power, it is needed the reduction of the tension and width of ring pack. The lower tension ring and the manufacturing technology of cast iron thinner width ring can bring the friction reduction between the ring and liner during engine running. Therfore, the fuel economy can be achieved. Thereafter the engine emission can be reduced. In this study, by using a developed basic computer program that predicts the inter-ring pressure, the motion of ring and the inter-ring pressure through a crevice volume model between adjacent rings, and the oil film thickness and the friction computed by lubrication theories, it is to be examined the effect of friction reduction from piston ring pack equipped with thinner width ring and lower tension ring.

• 대한가정학회지
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• 제36권6호
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• pp.85-94
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• 1998

In this study we tested the physiological influence on human-body according to clothing pressure with reduction rate and varied posture using three kinds of belt with different width. The width of belts were 2.5cm, 3.5cm and 4.5cm, and reduction rates of belts were 0%, 2.5% and 5% of the subject/s waist size respectively. the measured postures were standing state and sitting stste in the chair. The reasults are as follows; 1. Clothing pressure was high in the order of Side part>Front part>Back part and the rate fo change in the side part was highest, according to the reductio rate of belts. The more the width of belt was wide, the less the clothing pressure was small, and this kind of phenomenon could be explained by "The Principle of the power". 2. Both the rate of reduction of belt and the change of average skin temperature in accordance with the width of belt is small, however, the more the width of belts is wider and the reduction rate is bigger, the more the skin temperature at the waist part is increased. 3. The blood pressure and pulse was influenced when the width of belt was narrow and the reduction rate was high. 4. A sense restraining was much influenced by the width of belt, especially when the width of belts was wide, the significant difference was permitted.permitted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.544-548
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• 2007

In general, final width of hot strip should be accomplished in this stage because width reduction of strip hardly appears during typical finishing mill. However, it is difficult to control the width of strip in the roughing mill process as the horizontal rolling of strip is subsequently performed after the vertical rolling. It is therefore important to obtain the deformation rolling direction on strip width to minimize the width spread of strip during horizontal rolling after vertical rolling. Generally there is Sizing press type and Edger-roll type. The width reduction process in sizing press has small amount of width spread compared with the edger. However, productivity by the sizing press process is much lower than those of the edger. In this study, sizing press and Edger-roll process parameters in a sheet rolling mill were set at specified values and the effect of the change in these parameters on product quality and process performance were evaluated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.650-650
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• 2013

Although imprinted nanopatterns of organic polymer can be modified by the heat treatment [1], it generally requires high process temperatures and is material-dependent since the heat-induced mass loss of the organic polymer is greatly affected by its chemical characteristics. When oxygen is added during the annealing process, one can reduce the process temperature as well as the dependence of the materials. With the oxygen, line width reduction of a polymer (SU-8) patterns could be accomplished at temperature of as low as $250^{\circ}C$ which was not possible in the heat only process. This oxidative line width reduction can be dramatically promoted with the introduction of oxygen plasma. The oxygen plasma, with its highly-reactive oxygen species, vigorously etches away the organic materials, proven to be extremely effective line with reduction method. It is, however, very hard to control the extent and homogeneity of the etching, particularly of very fine patterns. Here, we report an effective and reliable line width reduction method of imprinted nanopatterns by combined plasma and heat treatment. The merits of this process include the reduction of process temperature, time and material-dependence.

• 소성∙가공
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• 제4권2호
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• pp.151-158
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• 1995

In this study, the width spreads of spring steel including Mn-Cr steel(SUP 9A), Mn-Cr-V steel(SUP 11A), and Si-Cr steel(SAE 9254) and were investigated under different reduction ratios and thickness-width ratios friction coefficients. The experimental results were compared with the theoretical prediction by the Ekelund equation, Geuze equations, etc. The width spreads of the three spring steels were found to be 10-15% larger than mild steel, and the optimal reduction ratio for the spring steel was found in a range from 20 to30%. Among the spring steels, the width spread of Mn-Cr-V steel was measured to be the largest followed by those of Si-Cr steel and Mn-Cr steel. It was found that the width spread increased with friction coefficient, width-thickness ratio and reduction ratio as predicted. However, the theoretical predictions revealed smaller width spread than the experimental results. This finding indicates that the coefficients of the width spread of the theoretical models need to be modified in order to predict the actual behavior of the width spreading of the spring steels. In this study, the coefficients of width spread of the Geuze equation were determined from the experimental results.

• 소성∙가공
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• 제12권7호
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• pp.668-674
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• 2003

Rigid-plastic finite element analyses on the deformation of slabs at various width reductions have been performed. By using commercial finite element code, dog-bone profile, crop profile and the longitudinal width profile after edging and Horizontal rolling have been analysed. The deformation behavior of slab for the heavy edger mill has also been compared with that for the sizing press. From the deformation analyses, it was found that the sizing press-horizontal rolling method is more efficient in width reduction than that of heavy edger mill-horizontal rolling. The results of finite element analyses fer the deformation of slab were well confirmed by the actual operational data. It was found that the amount of width variation after sizing and rolling is about 5∼10mm.

• Tribology and Lubricants
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• 제38권6호
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• pp.261-266
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• 2022

Notably, laser surface patterning facilitates tribological applications under lubricated sliding contacts. Consequently, a special pattern that can reduce the coefficient of friction under contact is considered necessary for improved machine efficiency. However, inappropriate pattern designs produce higher friction coefficients and cannot reduce friction. In this study, we use cast iron pins as specimens to investigate their friction and wear characteristics. Moreover, we experimentally investigate the correlation between the friction reduction effect and the design of groove crosshatch patterns fabricated with various angles and widths. We conduct a friction test using a pin-on-disc type tribometer under grease lubrication to study the friction reduction effect of the specimens, and we observe that the average coefficient of friction changes with the crosshatch angle and width. The experiment reveals that grooved crosshatch specimens with a crosshatch angle of 135°maximize friction reduction. The coefficient of friction of the groove specimens with a width of 120 ㎛ is lower than that of the specimens with a width of 200?. The friction reduction effect of the width of the groove is attributed to the density of the groove pattern. Thus, grooved crosshatch patterns can be designed to maximize friction reduction, and the friction property of a grooved crosshatch pattern is found to be related to its width and angle.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.223-225
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• 2007

Online models predicting roll force and forward slip of roughing mill was developed using nondimensional parameters. Using the effective inlet thickness, roll force model take into account the effect of inlet dog-bone shape of slab which take places after width reduction through edger rolling in roughing mill. The prediction accuracy of the proposed model is examined through comparison with measurements.

• 대한치과교정학회지
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• 제30권3호
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• pp.367-375
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• 2000

하악전돌증(mandibular prognathism or mandibular prognathic patient) 환자의 경우 전후방과 수직적 악골(maxilla)의 부조화정도가 심하거나 안면측모(facial profile)에 대한 심미적 인식도가 클 때에는 교정치료만으로는 심미적으로 만족한 결과를 얻기가 어려우므로 악교정수술(orthognathc surgery)과 병행되어야만 한다. 이럴 경우 심미적인 개선은 환자의 치료결과에 대한 만족도에 중요한 요소가 되고 있지만 미에 대한 기준을 객관화하는데는 많은 문제점을 갖고 있어 그 평가도 환자자신의 주관적인 관점에 의하여 내려지게 된다. 우리나라의 경우 얼굴심미에 대한 기준이 서구인의 외형을 선호하는 경향이 있어 전통적인 둥그런 얼굴보다는 달걀형의 갸름한 얼굴모양을 선호한다. 이 연구는 하악전돌증으로 인한 악교정수술결과 술후 얼굴폭이 넓어져 수술전보다 얼굴의 모양이 둥그렇게 되었다고 호소하는 환자가 있어 시도하게 되었다. 악교정수술전후의 안모길이 및 폭경의 변화에 관한 연구를 위하여 하악전돌증을 주소로 악교정수술을 받은 총 14명 환자(남자 8명, 여자 6명)의 정모두부방사선사진 계측(skull PA analysis)과 설문조사를 통하여 수술후의 안모변화 및 환자의 만족도에 대한 분석을 시행하여 다음과 같은 결론을 얻었다. 1. 14명의 환자중 3명($21.4\%$)이 얼굴이 넓어졌다고 답하였다. 2. 악교정수술(orthognathic surgery)후 하악골폭경 (mandibular width)은 A군은 변화가 없었으며, B군은 0.7mm 감소하였고, 안면폭경 (zygomatic width)은 A군에서는 0.45mm, B군에서는 0.66mm의 증가를 보였다. 3. 악교정수술후 얼굴길이의 변화는 A군에서는 상안면 고경(upper facial height)이 0.52mm증가, 하안면고경(lower facial height)이 1.19mm감소, 하악골 고경(mandibular height)이 0.7mm감소하였으며, B군에서는 상안면 고경이 0.67mm 감소, 하안면고경이 3.66mm 감소, 하악골 고경이 5mn감소하였다. 4. 수술후 안면폭경에 대한 안면고경(facial height)의 비율은 A군에서 $1.5\%$, B군에서 ,$3.6\%$ 감소하였다. 5. 수술후 안면폭경에 대한 하악골 길이(mandibular height)의 비율은 A군에선 $1.3\%$, B군에서 $4.4\%$ 감소하였다. 6. 수술후 하악골폭경에 대한 하악골 길이(mandibular height)의 비율은 A군에서 $1.3\%$, B군에서 $4.3\%$ 감소하였다. 7. 수술로 인한 얼굴폭의 변화는 무시할만한 것으로 판단되나 수술후 얼굴의 길이가 짧아져 상대적으로 얼굴의 폭이 넓어보일 수 있으므로 수술시 이에 대한 충분한 고려 및 환자에 대한 설명이 있어야 한다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.92-93
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• 2021

In the case of medical facilities, the evacuation time is delayed due to the decrease in the number of people in the hallway and exits due to the increase in the width of evacuation by using mobile beds, wheelchairs, crutches, etc. Accordingly, it is considered to secure evacuation capacity to reduce evacuation time according to corridor width and exit width. Accordingly, we would like to compare the standards related to the evacuation capacity of medical facilities in Korea and NFPA, derive differences, and use evacuation simulations to compare evacuation times according to changes in corridor width and exit width. In Korea, it is calculated based on the floor area by use, but in the case of NFPA 101, the number of evacuation routes, stair width, corridor exit width, and two-way door width was stipulated depending on the number of people. Using evacuation simulation, efficient evacuation capacity is calculated according to the reduction of evacuation time by changing the width of the hallway, changing the width of the exit, the width of the corridor, and the width of the exit. The evacuation simulation is intended to be used to secure evacuation safety of domestic medical facilities by calculating the effective evacuation time reduction by changing the width of the hallway and exit.