• 유공압시스템학회논문집
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• 제4권3호
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• pp.7-12
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• 2007

This paper presents an energy saving hydrostatic pressure exchanger for sea water desalination equipment. In a reverse osmosis(RO) system for desalinating sea water, more than 70 percent of the supplied sea water, brines which were impassable through RO membrane are bypassed, resulting in high energy losses. In this paper, a hydrostatic pressure exchanger consisting of an embedded water hydraulic piston motor and a water hydraulic piston pump was proposed and investigated in order to recover the energy of the bypassed brines. The pressurized brines are supplied to the embedded water hydraulic piston motor as power sources and the water hydraulic piston pump is driven by the output torque of the embedded water hydraulic piston motor as well as electric motor. Consequently, the energy of the bypassed brines can be recovered. To examine the electric energy saving characteristics of the hydrostatic pressure exchanger, a simulation model was constructed using commercial software and experiments were conducted. Through the results of simulation and experiment, the feasibility of the electric energy saving effect of the proposed hydrostatic pressure exchanger was investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.377-384
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• 2014

The requirement of acoustic material which is used in underwater environment more increases. The material is used to reduce acoustic signature and radiate noise for underwater vehicle. Underwater acoustic material was made by viscoelastic material such as a rubber and a polyurethane etc. The mechanical and acoustic characteristics of these material change with hydrostatic pressure. In order to increase an acoustic performance according to hydrostatic pressure, several kinds of scatterers were added to viscoelastic material. In this paper, acoustic modelling and analysis techniques of underwater acoustic material with hydrostatic pressure were introduced and proposed. The specimens for pulse tube test were made and echo reductions were calculated and measured with hydrostatic pressure. Also the characteristics of echo reduction of the specimens with hydrostatic pressure were obtained and discussed.

• 한국소음진동공학회논문집
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• 제24권11호
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• pp.868-875
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• 2014

The requirement of acoustic material which is used in underwater environment more increases. The material is used to reduce acoustic signature and radiate noise for underwater vehicle. Underwater acoustic material was made by viscoelastic material such as rubber and polyurethane etc. The mechanical and acoustic characteristics of these material change with hydrostatic pressure. In order to improve an acoustic performance according to hydrostatic pressure, several kinds of scatterers were added to viscoelastic material. In this paper, acoustic modelling and analysis techniques of underwater acoustic material with hydrostatic pressure were introduced and proposed. The specimens for pulse tube test were made and echo reductions were calculated and measured with hydrostatic pressure. Also the characteristics of echo reduction of the specimens with hydrostatic pressure were obtained and discussed.

• 한국정밀공학회지
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• 제22권5호
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• pp.159-166
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• 2005

A self-compensated water-hydrostatic bearing is well known to have advantages in stiffness. In this paper, its concept is extended to a hydrostatic journal bearing for achieving higher stiffness. The finite element method is applied to analyze the load characteristics of the self-compensated hydrostatic journal bearing. The analysis results reveal that the self-compensated journal bearing has higher load capacity and higher stiffness than conventional, fixed capillary journal bearings. and that this benefit degrades in the case of high eccentricity. Thus, a spindle system with self-compensated journal bearings must be designed to ensure a sufficiently large load capacity. A rectangular type capillary is also introduced with consideration of the practical application of the self-compensated hydrostatic journal bearing. Theoretical analysis results show that the rectangular type capillary is more beneficial than conventional annular type capillaries in practical use. The experimental verification on the analysis method is made to show that the experimental results are in good agreement with theoretical results.

• 한국식품저장유통학회지
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• 제18권1호
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• pp.1-6
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• 2011

고추장굴비의 지방산패를 최소화하기 위하여 신선굴비를 동결건조한 굴비포를 사용하여 고추장굴비를 제조하고 비열처리 살균방법으로 초고압과 감마선 처리하여 저장 중에 품질과 미생물변화를 분석함으로서 고추장굴비의 저장과 유통기간 연장 가능성을 검토하였다. 초고압처리(200, 400, 600 MPa) 및 감마선 조사(7, 10, 20, 30 kGy) 후 pH 변화는 유의적으로 차이가 없었으며 20일 동안 상온에서 저장 중에도 시료간의 유의적인 변화를 보이지 않았다. 색도는 Hunter L값과 b값은 증가하는 경향을 보였으며 a값은 감소하는 경향을 보였으나 외관상 품질에 영향을 미칠 정도는 아니었다. 휘발성 염기질소 대조구와 처리구에서 저장 중 경시적으로 증가하는 현상을 보였으나 초고압처리 압력이 높을수록, 감마선 조사강도가 높을수록 유의적으로 현저히 낮은 증가율을 보였다. TBA값은 모든 시료에서 시간이 경과함에 따라 증가량의 차이는 있으나 증가하는 경향을 보였으며, 초고압 처리하지 않은 경우 초기 0.6 mg/g 수준에서 20일 저장 후 4.2 mg/g 수준으로 높은 증가율을 보였으며, 600 MPa 처리구와 30 KGy 처리구의 경우 각각 1.2mg/g과 1.5 mg/g 수준으로 현저하게 낮은 값을 보였다. 초고압처리에 의한 호기성 생균수 감소효과는 다소 낮은 편이었으며 10 kGy 이상의 방사선 조사에 의해 효과적으로 미생물 수를 감소시켰다. 특히 30 kGy 처리구의 경우 20일 동안 저장 후에도 검출되지 않아 멸균효과를 얻을 수 있었다. 고추장 굴비 대중화를 위해서 진공포장이 기본적으로 요구되며, 초고압처리 방법은 단기적인 유통기한 연장효과를 기대할 수 있으며 장기적인 효과를 위해서는 감마선 조사가 적합할 것으로 판단된다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.123-124
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• 2002

A press shoe is an element of a machine for squeezing water from wood pulp in the field of manufacturing paper. This is used to compress the pulp enveloped by felt sheet with a large roller. The squeezing force is made by hydraulic pressure. The press shoe has a mechanism similar to a partial hydrostatic bearing. The pressure profile between press shoe and roller affects their squeezing ability, and partial peak pressure can tear the wet pulp. The curvature of the surface of press shoe varies to reduce the peak pressure and increase the mean pressure simultaneously. Therefore, the prediction of pressure distribution considering partially changed curvature of hydrostatic bearing is very important for designing the press shoe. In this study, the difference formulation of Reynolds' equation for partial hydrostatic bearing is by direct numerical method and a computer program to calculate the pressure distribution is developed. We investigate the effect of partially changed curvature of bearing surface on the pressure distribution. Other design parameter for hydrostatic bearing such as depth of pocket and relative velocity are also studied.

• KSBB Journal
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• 제23권5호
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• pp.362-368
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• 2008

본고에서는 초고압 시스템 (High hydrostatic pressure (HHP))의 특성, 종류, 응용을 예로 들어 설명하였다. 초고압 기술은 식품의 살균, 식품 보존기간연장, 유효성분의 추출 등에 선택적으로 적합하게 적용하여 생물산업공정에 효율적으로 응용 할 수 있다. 초고압 시스템을 효율적으로 적용하기 위한 최적조건을 선정하는 것은 많은 조업 변수에 대한 고려를 해야 하는 힘든 작업이다. 따라서 하드웨어에 대한 기초 실험과 예비 생산을 통하여 공정에 대한 모사를 검증하고 생산 효율을 증가시킬 수 있다. 또한 초고압 시스템의 중요성이 증가함에 따라 고성능 및 사용이 더욱 편리한 시스템이 나타날 것이며, 많은 영역의 바이오산업에서 필수적으로 이용될 것이다.

• 한국정밀공학회지
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• 제14권12호
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• pp.114-120
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• 1997

For compensating the error motion of hydrostatic tables, we have introduced a way that the clearance of table is controlled corresponding to the amount of eror with the actively controlled variable capillary, named as ACC. In previous paper, through the basic test, it was confirmed that by the use of ACC, the error motion within 2.7$\mu$ m of a hydrostatic table could be compensated with the resolution of 27nm, 1/100 contollable range, and with the frequency bandwidth of 5.5Hz, structurally. In this paper, we performed practical compensation of the linear and angular motion error of hydrostatic table using ACC. For improving the compensated motion accuracy, iterative control method is put into the control system. The experimental results show that by the simultaneous compensation of error, the linear and angular motion error are improved upto 0.25$\mu$ m and 0.4arcsec, which are about 1/10 and 1/3 of the non-compensated motion errors respectively.

• KSTLE International Journal
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• 제3권2호
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• pp.90-94
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• 2002

A press shoe is an element of a machine for squeezing water from wood pulp in the field of manufacturing paper. This is used to compress the pulp enveloped by felt sheet with a large roller. The squeezing farce is made by hydraulic pressure. The press shoe has a mechanism similar to a partial hydrostatic bearing. The pressure profile between press shoe and roller affects their squeezing ability, and partial peak pressure can tear the wet pulp. The curvature of the surface of press shoe varies to reduce the peak pressure and increase the mean pressure simultaneously, Therefore, the prediction of pressure distribution considering partially changed curvature of hydrostatic bearing is very important far designing the press shoe. In this study, the difference formulation of Reynolds equation far partial hydrostatic bearing is derived by direct numerical method and a computer program to calculate the pressure distribution is developed. We investigate the effect of partially changed curvature of bearing surface on the pressure distribution. Other design parameter far hydrostatic bearing such as depth of pocket and relative velocity are also studied.

• 한국정밀공학회지
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• 제19권5호
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• pp.56-63
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• 2002

A new model utilizing a transfer function is introduced in the present paper for analizing motion errors of hydrostatic tables. Relationship between film reaction force in a single hydrostatic pad and form error of a guide rail is derived at various spacial frequencies by finite element analysis, and it is expressed as a transfer function. This transfer function clarifies so called averaging effect of the oil film quantitively. For example, it is found that the amplitide of the film reaction farce is reduced as the spacial frequency increases or relative width of the pocket is reduced. Motion errors of a multiple pad table is estimated from transfer function, geomatric relationship between each pads and form errors of a guide rail, which is named as Transfer Function Method(TFM). Calculated motion errors by TFM show good agreement with motion errors calculated by Multi Pad Method, which is considered entire table as an analysis object. From the results, it is confirmed that the proposed TFM is very effective to analyze the motion errors of hydrostatic tables.