• 한국산림과학회지
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• 제79권1호
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• pp.26-32
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• 1990

기내(器內)에서 배양(培養)된 5수종(樹種)의 Populus 류(類)(P. davidiana, P. maximowiczii, P. nigra, P. alba ${\times}$ P. glandulosa, P. nigra ${\times}$ P. maximowiczii)의 줄기를 Aluminium-EDTA가 0, 0.1, 0.2, 0.5, 1.0mM씩 첨가(添加)된 배지(培地)에 배양(培養)시켜 뿌리, 줄기, 잎의 생육(生育)상태를 조사(調査)하여 aluminium 내성(耐性)을 비교 분석하였다. 수종간(樹種間) Aluminium내성(耐性)의 차이(差異)는 비교적(比較的) 심(甚)하게 나타났고, 조사(調査)한 5수종중(樹種中) 사시나무가 가장강한 내성(耐性)을 지닌것으로 나타났다. Al-EDTA가 낮은 농도(濃度)로 첨가(添加)된 배지(培地)에서는 줄기와 뿌리생장에 촉진효과를 나타내는 종도 있었다. 1.0mM의 고농도(高濃度)에서는 사시나무 이외의 수종(樹種)에서는 발근(發根)이 억제되었다. 양버들, 황철, 현사시와 같은 내성(耐性)이 약(弱)한 수종(樹種)에서는 0.1mM의 낮은 농도(濃度)에서도 잎과 줄기에 형태적(形態的)인 변이현상이 나타났다. 양황철은 그 양친(兩親)인 양버들이나 황철보다 줄기생장(生長)에서 내성(耐性)이 증가했다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.45-48
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• 1997

The low frequency pulsed MIG welding process of new current waveform control to switch over unit pulse conditions (pulse current, pulse duration) in the fixed cycle was developed and its effect were investigated for aluminium and its alloy. By using this new welding process, the bead appearance having clear ripple pattern, such as TIG welding bead can be obtained and the gap tolerance of lap and butt welding joint can be expanded.

• 한국정밀공학회지
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• 제20권12호
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• pp.126-134
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• 2003

In order to investigate the effect of surface treatment in Aluminium alloy and Titanium alloy which are used to armor material during ballistic impact, a ballistic testing was conducted. Anodizing was used to achieve higher surface hardness of Aluminium alloy and Iron plating in PVD(Physical Vapor Deposition) method was used to achieve higher surface hardness of Titanium alloy. Surface hardness test were conducted using a Micro victor's hardness tester. Ballistic resistance of these materials was measured by protection ballistic limit(V-50), a statical velocity with 50% probability penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed from the results of V-50 test and Projectile Through Plates (PTP) test at velocities greater than V-50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V-50 tests were conducted with 0$^{\circ}$obliquity at room temperature with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration. and penetration modes of surface treated alloy laminates are compared to those of surface non-treated alloy laminates. A high speed photography was used to analyze the dynamic perforation phenomena of the test materials.

• 한국정밀공학회지
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• 제17권4호
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• pp.7-21
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• 2000

This paper describes an overview of the thixoforming and thixomolding processes. Semi-solid metalworking (SSM), which is called the thixoforming process of aluminium materials, incorporates the elements of both casting and for the manufacture of near net shape parts. The SSM has some advantages such as net shape or near net shape manufacturing, the ability to form thin walls, excellent surface finish, tight tolerance, and excellent dimensional precision. The thixomolding process of Mg alloy (AZ9l) is a combination of two technologies both conventional die casting and plastic injection molding. The feed material used is a machined chip with a geometry of approximately 1 mm square and a length of 2~3 mm. The semi-solid forming (SSF) of high quality aluminium and magnesium parts will be established in the automotive and electronic industry, in the future. The hybrid method of casting/forging has been caused attention. This process uses a preformed material made by casting instead of the wrought material and finishes it by a single forging process. This process is expected to lower costs without sacrificing the mechanical and finishes it by a single forging process. The process is expected to lower costs without sacrificing the mechanical properties. The authors, intending that the casting/forging process contributes to a reduction in production cost of aluminum automotive parts in Korea, describes the feature of the casting/forging process, aluminum alloys suitable for the cast preform, microstructure and mechanical properties of the cast preform, application examples of cast/forging, and further study.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.63-66
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• 2000

This research addresses study on thermal residual stress of a composite patch repair of the edge cracked aluminium panel of aging aircraft. Composite patch repair is an efficient and economical technique to improve the damage tolerance of cracked metallic structures. These are thermal residual stresses due to the mismatch of coefficient of thermal expansion, and these are affected by the curing cycle of patch specimen. In this study, three curing cycles were selected for F.E. analysis. This study features the effect on composite patch and aluminum by thermal residual stress during crack propagation in aluminum plate.

• 한국정밀공학회지
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• 제23권2호
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• pp.146-153
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• 2006

Acceleration sensors have widely been used in the various fields of industry. In recent years, micromachining accelerometers have been developed and commercialized by the micromachining technique or MEMS technique. Typical structure of such sensors consist of a cantilever beam and a vibrating mass fabricated on Si wafers using etching. This study investigates the feasibility of powder blasting technique for microfabrication of sensor structures made of the pyrex glass alternating the existing Si based acceleration sensor. First, as preliminary experiment, effect of blasting pressure, mass flow rate of abrasive and no. of nozzle scanning on erosion depth of pyrex and soda lime glass is studied. Then the optimal blasting conditions are chosen for pyrex sensor. Structure dimensions of designed glass sensor are 2.9mm and 0.7mm for the cantilever beam length and width and 1.7mm for the side of square mass. Mask material is from aluminium sheet of 0.5mm in thickness. Machining results showed that tolerance errors of basic dimensions of glass sensor ranged from 3um in minimum to 20um in maximum. This results imply the powder blasting can be applied for micromachining of glass acceleration sensors alternating the exiting Si based sensors.