• 한국소음진동공학회논문집
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• 제15권3호
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• pp.341-345
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• 2005

Structural Dynamics Modification (SDM) is a very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material properties and shape of structure. Among those of SDM technique, the method to change shape of structure has been mostly relied on engineer's experience and trial-and-error process which are very time consuming. In order to develop a systematic method to change structure shape, surface grooving technique is studied. In this work, the shape of base structure was modified to improve its dynamic characteristics such as natural frequencies via surface grooving technique. Grooving shape was formed by mergingthe neighboring small embossing elements after analyzing frequency increment sensitivities of all the neighboring emboss elements. For this process, Criterion Factor was introduced and the initial grooving was started from the element having highest strain energy and the grooving is expanded into neighboring element. The range of targeting grooving area to check its frequency variations restricted to their neighboring area to reduce the computation effort. This surface grooving technique was successfully applied to a hard disk drives (HDD) cover model to raise its natural frequency by giving some groove on its surface.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.826-829
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• 2004

Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of frequency variation analysis, groove shape was formed gathering the many small embossing elements. For this process, Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and initial grooving point was selected using high-strain energy. This surface grooving technique was successfully applied to the HDD cover model.

• 한국도로학회논문집
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• 제3권3호
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• pp.111-118
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• 2001

초대형 점보 항공기의 출현으로 인하여 활주로 표면의 마찰저항 성능이 중요하게 되었다. 우천시나 겨울철과 같은 특정한 기후에서 활주로 표면은 수막현상과 마찰력의 손실이 발생하여 항공기의 브레이크 기능이 저하되어 제동력을 잃게 된다. 이러한 문제를 해결하기 위해 많은 연구가 미국항공우주국, 미공군, 미연방항공청 등에 의해 수행되었다. 그 결과 다양한 종류의 마찰저항이 끈 포장표면 처리 방법이 개발되었다. 이러한 설계방법 가운데 대표적인 방법이 그루빙이다. 포장 그루빙 공법은 활주로 표면에 마찰저항을 증가시키고 수막현상을 감소시켜주는 장점이 있는 것으로 보고되고 있다. 본 연구는 인천국제공항의 A-2구간에 수행된 건식 그루빙의 시공결과를 평가한 것이다. 그루빙 시공중에 온도 게이지를 사용하여 포장체+의 온도를 측정하고 건식 그루빙중에 온도변화를 측정하였으며 컷트날의 마찰로 발생하는 그루빙 시공이 완료된 활주로에 물을 살수하고 뮤 미터와 수심측정기를 사용하여 마찰계수와 수심을 계측하였다. 시험결과, 그루빙은 포장체에 손상을 주지 않았으며 활주로 표면은 마찰저항이 증가하고 수막현상을 감소하는 효과가 현저하게 나타나서 건식 그루빙의 효과는 매우 큰 것으로 평가되었다.

• 동력기계공학회지
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• 제11권3호
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• pp.41-46
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• 2007

The microstructure and electrochemical analysis of welds of electric resistance welding(ERW) pipe were investigated. The direction of metal flow line in HAZ of ERW pipe shifted to the inner(or outer) surface of pipe by plastic deformation during welding. The lowest heat input welds of ERW pipe was showed crack by liquid penetrant testing. Accelerated corrosion test by constant current density of 20mA/$cm^{2}$ developed groove at the welds of ERW pipe and the measured grooving factors were about $1.2{\sim}1.5$. Corrosion potential of base metal obtained by cyclic polarization in artificial sea water(3.5wt.% NaCl solution) was 100mV higher than that of weld metal of ERW pipe.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1280-1287
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• 2002

The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass, silicon and ceramics, capable of producing micro structures larger than $100{\mu}$ m. This paper describes the performance of powder blasting technique in micro-line grooving of glass and the effect of the number of nozzle scanning on the depth and width of line groove. Experimental results showed that increasing the no. of nozzle scanning resulted in the increase of depth and width in grooves. Increase of width which may cause several problems in the precision machining results from wear of mask film. Therefore, well-controlled masking process is the most important factor for micro machining of glass with accuracy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.859-863
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• 2004

Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of sensitivity analysis, groove shape was formed gathering the many small embossing elements. For this process, Sensitivity Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and that result was very successful.

• Journal of Mechanical Science and Technology
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• 제17권2호
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• pp.239-245
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• 2003

Ultra precision diamond cutting is a very efficient manufacturing method for optical parts such as HOE, Fresnel lenses, diffraction lenses, and others. During micro cutting, the rake angle is likely to become negative because the tool edge radius is considerably large compared to the sub-micrometer-order depth of cut. Depending on the ratio of the tool edge radius to the depth of cut, different micro-cutting mechanism modes appear. Therefore, the tool edge sharpness is the most important factor which affects the qualities of machined parts. That is why diamond, especially monocrystal diamond which has the sharpest edge among all other materials, is widely used in micro-cutting. The majar issue is regarding the minimum (critical) depth of cut needed to obtain continuous chips during the cutting process. In this paper, the micro machinability near the critical depth of cut is investigated in micro grooving with a diamond tool. The experimental results show the characteristics of micro-cutting in terms of cutting force ratio (Fx/Fy), chip shape, surface roughness, and surface hardening nea. the critical depth of cut.

• 한국산학기술학회논문지
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• 제10권1호
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• pp.19-24
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• 2009

구조물 동특성 변경법이란 부가 구조물의 첨가나 삭제, 재료 물성치의 변경, 구조물의 형상변경 등을 이용해 구조물의 동특성을 향상시킬 수 있는 매우 효과적인 방법이다. 하지만 이러한 구조물 동특성 변경법 중 구조물의 형상 변경을 통해 그 구조물의 동특성을 향상시키는 방법은 지금까지는 주로 엔지니어의 경험이나 많은 시간을 요하는 시행착오법에 의존해 왔다. 따라서, 앞선 연구를 통해 이러한 구조물의 형상 변경을 통한 동특성변경법에 있어서 기존의 경험이나 시행착오법에 의존하는 방법이 아닌, 체계화된 방법론을 제안하게 되었으며 하드디스크 드라이브 (HDD)에 성공적으로 적용하였다. 제안된 그루브를 통한 표면형상변형 동특성변경법을 검증해 보기 위하여, 본 연구에서는 모든 요소가 엠보싱 되어 있는 극한의 경우로부터 최적화를 수행하고 앞선 연구에서 얻어진 최적화 결과와 비교함으로써 제안된 방법론의 효과를 검토해 볼 수 있었으며, 1차 고유진동수를 높이기 위한 최적화 결과 그루브의 형상은 앞선 연구결과와 같음을 알 수 있었다.

• The Plant Pathology Journal
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• 제22권2호
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• pp.168-173
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• 2006

To develop the diagnostic method for the viral infection in apple, the partial genes corresponding to the N-terminal region of RNA polymerase of Apple stem grooving virus (ASGV) and coat protein of Apple chlorotic leaf spot virus (ACLSV) were characterized from the infected apple cultivars in Korea. Based on the nucleotide sequences of the characterized partial genes, the virus gene-specific primers were designed for the detection of ASGV and ACLSV infected in species of Malus. The RT-PCR using the primers for the genes of ASGV and ACLSV successfully gave rise to 404 and 566 bp DNA fragments, respectively. Using those viral gene-specific primers, the multiplex RT-PCR assays were also established to diagnose the mixed infection by ASGV and ACLSV simultaneously. Furthermore, the control primers, which have to be included for the RT-PCR as an internal control, were designed using the nucleotide sequence of the gene encoding elongation factor $1{\alpha}(EF1{\alpha})$. This multiplex RT-PCR including the control primers provides more reliable, rapid and sensitive assay for the detection of ASGV and ACLSV infected in Korean apple cultivars.

• 한국생산제조학회지
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• 제18권6호
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• pp.551-557
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• 2009

A development of smart materials is becoming a prominent issue on present industries. A smart material, included in functions, is needed for micro fabrication. A shape memory alloy(SMA) in a smart material is best known material. Ni-Ti alloy, composed of nikel and titanium is one of the best shape memory alloy(SMA). Nitinol SMA is used for a lot of high tech industry such as aero space, medical device, micro actuator, sensor system. However, Ni-Ti SMA is difficult to process to make a shape and fabrications as traditional machining process. Because nitinol SMA, that is contained nikel content more than titanium content, has similar physical characteristics of titanium. In this paper, the characteristics of ECM grooving process for nitinol SMA are investigated by experiments. The experiments in this study are progressed for power, gap distance and machining time. The characteristics are found each part. Fine shape in work piece can be found on conditions; current 6A, duty factor 50%, gap distance 15%, gap distance $15{\mu}m$, machining time 10min.