• Journal of Chest Surgery
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• 제45권6호
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• pp.368-379
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• 2012

Background: Bioprostheses for cardiovascular surgery have limitations in their use following as calicification. ${\alpha}$-galactosidase epitope is known as a stimulant of immune response and then shows a progressing calcification. The objective of this study was to evaluate histologic characteristics and mechanical properties of decellularization and treated with ${\alpha}$-galactosidase. Materials and Methods: Bovine pericardial tissues were allocated into three groups: fixation only with glutaraldehyde, decellularization with sodium dodesyl sulfate and decellularization plus treatment with ${\alpha}$-galactosidase. We confirmed immunohistological characteristics and mechanical properties as fatigue test, permeability test, compliance test, tensile strength (strain) test and thermal stability test. Results: Decellularization and elimination of ${\alpha}$-gal were confirmed through immunohistologic findings. Decellularization had decreased mechanical properties compared to fixation only group in permeability (before fatigue test p=0.02, after fatigue test p=0.034), compliance (after fatigue test p=0.041), and tensile strength test (p=0.00). The group of decellularization plus treatment with ${\alpha}$-galactosidase had less desirable mechanical properties than the group of decellularization in concerns of permeability (before fatigue test p=0.043) and strain test (p=0.001). Conclusion: Favorable decellularization and elimination of ${\alpha}$-gal were obtained in this study through immunohistologic findings. However, those treatment including decellularization and elimination of ${\alpha}$-gal implied the decreased mechanical properties in specific ways. We need more study to complete appropriate bioprosthesis with decellularization and elimination of ${\alpha}$-gal including favorable mechanical properties too.

• 대한기계학회논문집B
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• 제36권2호
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• pp.117-123
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• 2012

본 연구에서는 벌지 실험과 나노 압입 실험을 통해 박막의 기계적 물성을 측정하였다. 벌지 실험은 외적 지지구조를 가지지 않는 박막 시편의 한 면에 일정한 압력을 가하여 박막의 변위를 측정, 압력과 변위의 관계를 이용하여 박막의 기계적 물성을 측정하는 실험이다. 나노 압입 실험은 시편에 압입 방향으로의 하중과 시편의 표면으로부터 압입자의 깊이에 대한 데이터를 통하여 시편의 기계적 물성을 측정하는 실험으로 modified King's model 을 이용하여 모재의 영향이 고려된 박막의 물성을 구할 수 있다. 두 실험은 탄성 계수와 푸아송비의 수학적 관계가 다르기 때문에 벌지 실험과 나노 압입 실험결과로부터 박막의 탄성계수와 푸아송비를 동시에 측정할 수 있다.

• Tribology and Lubricants
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• 제32권5호
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• pp.154-159
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• 2016

This paper presents an experimental study of the leakage performance and endurance performance of a mechanical face seal in the 7-ton-class turbopump of the Korea Space Launch Vehicle 2 third-stage engine. We install a mechanical face seal between the fuel pump and turbine to prevent the mixing of the fuel and turbine gas. We design and manufacture a prototype mechanical face seal, which has two parts, namely, a bellows seal assembly and mating ring. We set up a test facility to measure the leakage and endurance of the mechanical face seal. For the similarity tests, we use water under real operating conditions such as high rotational speed, high temperature, and high pressure. Through investigation of the leakage and carbon wear rate, it is possible to evaluate the performance of the mechanical face seal. The results of the leakage and endurance performance test demonstrate the absence of any leakage from the prototype mechanical face seal after a trial run and clarify that the acceptable wear rate fully satisfies the turbopump requirements. Finally, we install a qualified mechanical face seal in a 7-ton-class turbopump and perform a validation test in the turbopump real-propellant test facility in the Korea Aerospace Research Institute. The test results confirm that the mechanical face seal works well under real operating conditions.

• 한국유체기계학회 논문집
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• 제10권1호
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• pp.20-25
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• 2007

A mechanical face seal has been tested in Korea Aerospace Research Institute for turbopump applications. In this paper the acceptance test results of the mechanical face seal are described. By means of simulating a practical operating environment, the performance against leakage of mechanical face seal is monitored. In addition the carbon wear is measured to estimate the life of a mechanical face seal. The test results show the acceptable leakage performance and resonable wear tendency as well. Lastly the repeated test had been carried out to guarantee the endurance performance of mechanical face seal based on the turbopump life.

• 한국식품조리과학회지
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• 제9권2호
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• pp.78-81
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• 1993

"Yut Kang Jung" is a kind of Korean traditional cookie. The purpose of this study is to examine the effects of various kinds of syrups and cooking methods of Yut Kang Jung. The quality of Yut Kang Jung was evaluated by sensory and Instron machine test. The results is as follows; 1. The Recipe of the best Yut Kang Jung is this: White sesame 120g, sugar syrup 40g, and crude maltose watery 50g are used. Mixing sugar syrup crude maltose watery boiling for 4 min, in temperature $105^{\circ}C$. The sugar density after boiling was 86%. 2. Yut Kang Jung made by sugar syrup and crude watery maltose got the best result in sensory best. 3. Yut Kang Jung made by crude watery maltose got the best result in mechanical test. 4. The comparison between the sensory test & mechanical test were as follow; The hardness in the mechanical test was comparable with hardness & fracturability in the sensory test, and the chewiness in the mechanical test was comparable with flavor, adhesiveness, fractur ability in sensory test.

• Steel and Composite Structures
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• 제33권2호
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• pp.299-306
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• 2019

The natural fibre composites are termed as bio-composites. They have shown a promising replacement to the current carbon/glass fibre reinforced composites as environmental friendly materials in specific applications. Natural fibre reinforced composites are potential materials for various engineering applications in automobile, railways, building and Aerospace industry. The natural fibre selected to fabricate the composite material is plant-based fibre e.g., sisal fibre. Sisal fibre is a suitable reinforcement for use in composites on account of its low density, high specific strength, and high hardness. Epoxy is a thermosetting polymer which is used as a resin in natural fibre reinforced composites. Hand lay-up technique was used to fabricate the composites by reinforcing sisal fibres into the epoxy matrix. Composites were prepared with the unidirectional alignment of sisal fibres. Test specimens with different fibre orientations were prepared. The fabricated composites were tested for mechanical properties. Impact test, tensile test, flexural test, hardness test, compression test, and thermal test of composites had been conducted to assess its suitability in industrial applications. Scanning electron microscopy (SEM) test revealed the microstructural information of the fractured surface of composites.

• 열처리공학회지
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• 제3권1호
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• pp.25-33
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• 1990

Recently developed austempered ductile irons(A.D.I.) have good mechanical properties. However it is still needed to examine the relationships between microstructures related to banitic reaction and the mechanical properties. From the mechanical tests such as impact test, hardness test, tensile test, and the microstructure observations, we concluded that the good mechanical properties of A.D.I. came from the fine banitic ferrite structure formed during the first stage of the austempering reaction.

• 전기학회논문지
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• 제66권11호
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• pp.1651-1656
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• 2017

This paper deals with the thermal and mechanical properties of ceramic coating material for bus bars. A ceramic coated samples were prepared for the mechanical properties test. There are two types of samples. One is a square shape and the other is a busbar shape. Each sample was deteriorated for 30 days to compare the thermal and mechanical properties with the non-degraded samples. Two thermal properties tests are TGA and flammability tests, and four mechanical properties tests are drop impact test, cross cut, tensile test, and bend test. The ceramic coating material was never damaged by impact and did not separate from aluminum in the cross cut test. In the tensile test, the breakage of the insulating material did not occur until aluminum fractured, and the breakage of the insulating material did not occur until the maximum load in the bending test. The decomposition temperature (melting point) of the ceramic coating material was higher than that of other epoxy insulators. This ceramic coating material is nonflammable and it has excellent fire stability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.252-257
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• 2004

Nanometer-sized structures are being applied to many devices including micro/nano electronics, optoelectronics, quantum devices, MEMS/NEMS, biosensors, etc. Especially, the thin film with submicron thickness is a basic structure for fabricating these devices, but its mechanical behaviors are not well understood. The mechanical properties of the thin film are different from those of the bulk structure and are difficult to measure because of its handling inconvenience. Several techniques have been applied to mechanical characterization of the thin film, such as nanoindentation test, micro/nano tensile test, strip bending test, etc. In this study, we focus on the strip bending test because of its high accuracy and moderate specimen preparation efforts, and measure Au thin film, which is a very popular material in micro/nano electronic devices. Au film is deposited on Si substrate by evaporation process, of which thickness is 100nm. Using the strip bending test, we obtain elastic modulus, yield and ultimate tensile strength, and residual stress of Au thin film.

• 한국수소및신에너지학회논문집
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• 제33권2호
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• pp.158-163
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• 2022

The test method on the Type II high-pressure hydrogen storage tanks made of the metal wire hoop winding is a complex and high risk. Also closeup on the tank being test is difficult. In this study, we studied a mechanical test method for a high-pressure hydrogen tanks. This method must be simple, risk-free and possible to observe the change in microscopic behavior of a metal wire on a liner. As the results, it was possible to observe the microscopic behavior on the metal wire by the mechanical test method. Also, a simple and risk-free test was possible compared to the conventional test method for high pressure hydrogen tanks.