• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.257-258
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• 2018

PTFE(polytetrafluoroetylene) is widely used as representative sliding friction materials, but there could be difficulties in applying it to various industry fields by the shortage of carrying capacity under high facial pressure and by the change of friction coefficient according to the environmental conditions. Accordingly, this study was to do comparative analysis on the friction coefficient by environmental temperature at the same facial pressure of UHMWPE which was mainly used as sliding friction materials under high facial pressure. In addition, this study was to proceed with the double shear structure by using two test specimen in order to minimize the frictional forces.

• 대한기계학회논문집A
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• 제34권9호
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• pp.1249-1255
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• 2010

초고압 시스템은 유압동력 발생장치, 충격압력 발생장치, 초고압부 오일 보충장치, 기동 및 제어반 등으로 일반적으로 구성된다. 유압동력 발생장치는 초고압 발생기에 유압원을 공급하고, 초고압 발생기에서는 공급되어진 유압원을 이용하여 초고압으로 압력을 증폭한다. 기동 및 제어반에서는 시스템을 운전하기 위한 전기모터, 밸브, 센서 등에 대한 제어 및 관찰을 하기 위해 사용된다. 본 연구에서는 초고압 압력을 발생시키기 위한 제어 방법을 서보밸브를 사용한 유량제어 방식에서 비례 릴리프 밸브를 사용한 압력제어 방법을 사용하여 연구하며, 초고압 압력 발생기의 압력을 가하는 주기와 유압동력 발생장치의 작동유의 온도 변화에 따라 충격압력을 발생시키는 성능이 변화하는 특성을 연구하는 것을 목적으로 한다.

• International Journal of Fluid Machinery and Systems
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• 제7권3호
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• pp.125-129
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• 2014

The paint removal and recoating are the very important process in airplane maintenance. The traditional technology is to use the chemical way corroding the paint with paint remover. For changing the defects, corrosion & pollution & manual working, of the traditional technology, the physical process which removes the paint of airplane with 250MPa/250kW ultra-high pressure rotary water jetting though the surface cleaner installed on the six axes robot is studied. The paint layer of airplane is very thin and close. The contradiction of water jetting paint removal is to remove the paint layer wholly and not damage the surface of airplane. In order to solve the contradiction, the best working condition must be reached through tests. The paint removal efficiency with ultra-high pressure and move speed of not damaged to the surface. The move speed of this test is about 2m/min, and the paint removal efficiency is about $30{\sim}40m^2/h$, and the paint removal active area is 85-90%. No-repeat and no-omit are the base requests of the robot program. The physical paint removal technology will be applied in airplane maintenance, and will face the safety detection of application permission.

• 한국분말재료학회지
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• 제10권3호
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• pp.181-185
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• 2003

Resistance sintering under ultra-high pressure if developed to fabricate W-Cu composite containing 5 to 80v/o copper. The consolidation was carried out under pressure of 6 to 8 GPa and input power of 18 to 23 kW for 50 seconds. The densification effect and microstructure of these W-Cu composites are investigated. The effect of W particle size on ,sintering density was also studied. The micro hardness was measured to evaluate the sintering effect.

• 동력기계공학회지
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• 제17권6호
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• pp.5-10
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• 2013

Diesel engines have the advantages of good fuel efficiency and low emissions. Therefore, car makers have been developed various kinds of diesel engine management system to clean up emissions while improving fuel efficiency. One of them is the common rail system. In the common rail system, diesel fuel is injected into the combustion chamber at ultra high pressures up to 1,800 bar to ensure more complete combustion for cleaner exhaust gas, and highly precise multiple injection reduces NOx emission, combustion noise and vibration. Generally speaking, common rail system consists of booster pump, high pressure pump, common rail, injectors, control valves, and sensors. The high pressure pump receives low pressure fuel from the booster pump and supply high pressure fuel to injectors through the high pressure common injection rail. Therefore, high pressure pump has an important role in common rail system. In this paper, we have investigated the performance of high pressure pump of common rail system.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1833-1839
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• 2004

Recently mass spectrometry and separation methods such as liquid chromatography have become major tools in the field of proteomics. In this report, we describe in detail our efforts to develop ultra-high pressure capillary reverse-phase liquid chromatography (cRPLC) and its online coupling to a mass spectrometer by a nanoelectrospray (nanoESI) interface. The RPLC system is constructed in house to deliver LC solvents at the pressure up to 20,000 psig, which is four times higher than conventional RPLC systems. The high operation pressure allows the efficient use of packed micro-capillary columns (50, 75 and 150 ${\mu}$m i.d., up to 1.5 m long). We will discuss the effect of column diameter on the sensitivity of cRPLC/MS/MS experiments and the utility of the developed technique for proteome analysis by its application in the analysis of proteome samples having different levels of complexity.

• KSTLE International Journal
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• 제4권2호
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• pp.66-72
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• 2003

This paper presents the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existing investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal choices of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high-speed spindle. In this paper, The pressure behavior in theory of air film in high speed region of journal according to the eccentricity of journal and the source positions analyzed. The theoretical analysis has been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high-speed milling.

• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.56-62
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• 2024

By introducing curing kinetics and chemo-rheology for the epoxy resin formulation for ultra-high voltage gas insulated switchgear (GIS) Insulating Spacers, a study was conducted to simulate the curing behavior, flow and warpage analysis for optimization of the molding process in automatic pressure gelation. The curing rate equation and chemo-rheology equation were set as fixed values for various factors and other physical property values, and the APG molding process conditions were entered into the Moldflow software to perform optimization numerical simulations of the three-phase insulating spacer. Changes in curing shrinkage according to pack pressure were observed under the optimized process conditions. As a result, it was confirmed that the residence time in the solid state was shortened due to the lowest curing reaction when the curing holding pressure was 3 bar, and the occurrence of deformation due to internal residual stress was minimized.

• 한국약용작물학회지
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• 제18권3호
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• pp.157-167
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• 2010

We investigated a method to improve anticancer activities of Acer mono wood extracts by ultra high pressure extraction process. The A. mono was extracted by water at $40^{\circ}C$ and 300 MPa for 15 min (High Pressure Extraction, HPE). The extraction yield by ultra high pressure extraction process was 5.42%. The cytotoxicity on human normal lung cell (HEL299) of the extracts from HPE showed 21.54% lower than that from conventional water extraction at $100^{\circ}C$ in adding the maximum concentration of 1.0 mg/$m{\ell}$. Ultra high pressure extracts process for 15 minutes extracts (HPE15) showed more potent scavenging effect than the control, BHA. On SOD-like test, the HPE15 showed highest activity as 32.4% at 1.0 mg/$m{\ell}$ concentration. Human stomach adenocarcinoma, liver adenocarcinoma, breast adenocarcinoma and lung adenocarcinoma cell growth were inhibited up to about 67~79%, in adding 1.0 mg/$m{\ell}$ of extracts from HPE. HPE was 20~25% higher than conventional water extraction. It was interesting that, among several cancer cell lines (stomach adenocarcinoma, liver adenocarcinoma), the growth of digestive related cancer cells were most effectively inhibited as about 75~79%. On in vivo experiment using ICR mice, the variation of body weight of mice group treated A. mono wood extracts from HPE of 100 mg/kg/day concentration was very lower than control and other group. The survival times of group treated this extracts was 61.96% longer than that of the control group and this extracts showed the lower tumor weight, which were 10.49 g than positive control as 16.17 g. Based on these results, we could tell that the HPE wood extracts of A. mono had higher anticancer activity than conventional water extraction. The results of HPE showed obvious advantages in higher efficiency, shorter extraction time, at lower energy costs.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.41-42
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• 2023

The physical performance of high-strength concrete deteriorates when exposed to high temperatures such as fire. In particular, in the case of ultra-high-strength concrete, there is a high possibility of explosion due to internal water pressure and thermal expansion due to the tight internal structure. In this paper, a fire resistance certification test was conducted for field application of ultra-high-strength fire-resistant concrete, and the fire resistance performance (temperature rise of main rebar) was compared according to the structural concrete cover thickness. As a result, when the covering thickness was 40 mm, three structures did not meet the certification standards, and when the covering thickness was 50 mm, all structures met the fire resistance certification standards.