• 한국표면공학회지
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• 제38권1호
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• pp.14-20
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• 2005

The control of internal stress is extremely important in electroforming because of the deliberately low adhesion between the electro form and the mandrel. Excessive tensile or compressive stress can cause distortion, separation problem, curling, peeling or separation of electroform prematurely from the mandrel, buckling and blistering. Nickel sulfamate bath has been widely used in electroforming because of its low internal stress and moderate hardness. In this study, real-time stress sensor has been used for stress control in chloride-free nickel sulfamate bath for 400 mm x 300 mm x 500 ㎛ nickel electroform. It was found that compressive stress found at low current density indicated the contamination of electrolyte, which is very useful in procuring buckling and peeling of electroform. No compressive stress is allowed for plate electroform. The real-time stress can also be used for accurate stress control of nickel electroform. The tensile stress was found to be increased slightly with increase in nickel electroform thickness, i.e., from initial 1.47 ksi to 2.02 ksi at 320 ㎛.

• 한국약용작물학회지
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• 제18권2호
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• pp.98-104
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• 2010

Eleuthero(Eleutherococcus senticosus Maxim.) cortex is well known as a herb medicine for tonic. This study was performed to improve the quality of dried E. senticosus cortex. Investigation of quality factor and contents of efficient compounds under different steaming times and drying methods were performed to determine the proper processing and drying conditions of Eleuthero cortex harvested on March in annual stems. The proper steaming time for peeling bark to make high quality Eleuthero cortex took less than 20 mins. Eleutheroside B and E contents among drying methods were significantly different at 5% level DMRT. The $50^{\circ}C$ heat drying was the most advisable condition for drying, when drying and keeping contents of effective compounds.

• 대한금속재료학회지
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• 제50권1호
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• pp.86-91
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• 2012

Ti-6Al-4V extra low interstitial (ELI) alloy has been widely used as an orthopedic implant material because of its excellent biocompatibility, corrosion resistance and mechanical properties. However, V-free titanium alloys such as Ti-6%Al-7%Nb and Ti-5%Al-2.5%Fe have recently been developed because of the toxicity of V. Hydroxyapatite (HA) is used as a coating material on Ti or Ti biomaterials due to its good biocompatibility. However, HA coated on Ti alloy causes a problem for tissue by peeling off during usage. Therefore, such peeling off during long time usage can be suppressed by adding HA in Ti or Ti alloy composites. The aim of this study was to manufacture an ultra fine grained (UFG) Ti-Nb-HA bulk alloy, which is usually difficult to fabricate using melting and casting technology, by rapid sintering process using high energy mechanical milled (HEMM) powder.

• Structural Engineering and Mechanics
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• 제77권1호
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• pp.75-87
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• 2021

The present study pertains to the introduction of two new types of grip adaptor for universal testing machines, namely Polyvinyl Chloride (PVC) and Polyoxymethylene (POM) grip adaptors, and their application to tension testing of FRP bars with different fiber and surface finish types. The tabs are connected to the FRP bar sample with the help of mechanical anchors, i.e. bolts. These new adaptors offer vital superiorities over the existing end tab designs (anchors with filling material or mechanical anchorage), including the reduction in the time and labor for production, reusability and the mild nature, i.e. low hardness of the tab material, which retards and even prevents peeling and crushing in the gripping regions of an FRP sample. The methods were successfully applied to FRP bars with different types of fiber (CFRP, GFRP and BFRP) and different types of surface texture (ribbed, wrapped, sand-coated and wound). The test results indicated that the both types of end caps prevented slip of the bar, crushing and peeling in the gripping zone. The mechanical properties from the material tests with the new caps were in perfect agreement with the ones from the material tests with steel tubular caps.

• 한국HCI학회논문지
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• 제1권1호
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• pp.45-52
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• 2006

본 논문은 GPU를 활용한 이미지 공간 실시간 충돌 검사 기법을 설명한다. 닫힌 물체들이 충돌하지 않는 경우, 뷰잉 레이를 따라 물체의 앞면과 뒷면이 번갈아 가며 나타나는 것을 확인 할 수 있다. 그러나 물체 간 충돌이 일어나는 경우 이 현상이 깨어지게 된다. 이러한 특성에 기반하여 본 논문은 충돌 검사에 필요한 최소한의 표면 정보만 텍스쳐에 기록하여 충돌 검사를 수행하는 기법을 제안한다. 이 기법은 GPU의 framebuffer object 와 vertex buffer object, 그리고 occlusion query 등의 기능을 활용한다. 이러한 GPU의 기능을 이용하면 통상적인 이미지 기반 충돌검사에서 사용하는 multi-pass rendering 과 context switch 부하를 줄일 수 있다. 즉 기존의 이미지 기반 충돌 검사에 비해 적은 렌더링 횟수와 적은 렌더링 부하를 가진다. 본 논문에서 제안된 알고리즘은 변형체나 복잡한 물체에도 적용이 가능하며, 3D 게임이나 가상현실과 같은 실시간 어플리케이션에 적용될 수 있는 성능을 발휘한다.

• Korea-Australia Rheology Journal
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• 제13권1호
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• pp.29-35
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• 2001

The development of filament stretching extensional rheometers over the past decade has enabled the systematic measurement of the transient extensional stress growth in dilute and semi-dilute polymer solutions. The strain-hardening in the extensional viscosity of dilute solutions overwhelms the perturbative effects of capillarity, inertia & gravity and the kinematics of the extensional deformation become increasingly homogeneous at large strains. This permits the development of a robust open-loop control algorithm for rapidly realizing a deformation with constant stretch history that is desired for extensional rheometry. For entangled fluids such as concentrated solutions and melts the situation is less well defined since the material functions are governed by the molecular weight between entanglements, and the fluids therefore show much less pronounced strain-hardening in transient elongation. We use experiments with semi-dilute/entangled and concentrated/entangled monodisperse polystyrene solutions coupled with time-dependent numerical computations using nonlinear viscoelastic constitutive equations such as the Giesekus model in order to show that an open-loop control strategy is still viable for such fluids. Multiple iterations using a successive substitution may be necessary, however, in order to obtain the true transient extensional viscosity material function. At large strains and high extension rates the extension of fluid filaments in both dilute and concentrated polymer solutions is limited by the onset of purely elastic instabilities which result in necking or peeling of the elongating column. The mode of instability is demonstrated to be a sensitive function of the magnitude of the strain-hardening in the fluid sample. In entangled solutions of linear polymers the observed transition from necking instability to peeling instability observed at high strain rates (of order of the reciprocal of the Rouse time for the fluid) is directly connected to the cross-over from a reptative mechanism of tube orientation to one of chain extension.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.281-291
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• 2022

Global warming is accelerating due to the use of fossil fuels that have been used continuously for centuries. Now, humankind recognizes its seriousness, and is conducting research on searching for eco-friendly and sustainable energy. In the field of solar energy, which is a kind of eco-friendly and sustainable, many studies are being conducted to enhance the output performance of the module. In this study, the output improvement for the shingled module structure was studied. In order to improve the output performance of the module, the thickness of the encapsulant was increased, and the lamination process conditions have been improved accordingly. After that, the crosslinking rate was analyzed, and the suitability of the lamination process conditions was judged using this. In addition, a peeling test was conducted to analyze the correlation between the adhesion of the encapsulant and the output performance of the module. Finally, the optimization for the encapsulant material and the lamination process conditions for high-power shingled modules was established, and accordingly, the market share of high-power shingled modules in the solar module market can be expected to rise.

• 한국정밀공학회지
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• 제16권7호
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• pp.210-218
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• 1999

Sheet deposition type rapid prototyping system have many advantages : high build speed, low operating cost, large part size, no phase change, no need for support generation, and forth. However, those sheet deposition type rapid prototyping system require an additional post processing to remove excessive material attached to the part. This post processing is time consuming and labor intensive. Moreover, it is difficult for those system to fabricate parts with hollow cores and internal cavities. A new sheet deposition type rapid prototyping system that minimizes the post processing is proposed. The proposed system automatically removes excessive material in a peeling-off process between two cutting processes. In this way, the proposed system can reduce the post-processing time and cost as well as the limitation of the feasible geometric shapes in the conventional sheet deposition system.

• 한국자원식물학회지
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• 제27권1호
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• pp.72-79
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• 2014

본 연구는 마찰과 칼날 박피방식과 저장온도에 따른 박피밤의 품질 변화를 조사하기 위하여 수행되었다. 박피밤의 중량감소율은 저장기간 동안 모든 처리구에서 관찰되었으며, 박피방식에 따른 차이는 관찰할 수 없었다. 그러나 박피밤의 수분함량은 모든 처리구에서 저장기간에 따라 감소하는 경향을 보였는데, 마찰박피밤이 모든 처리구에서 칼날박피밤 보다 수분함량이 높았다. 박피밤 색도의 경우 a, b, ${\Delta}E$값은 모든 처리구에서 저장기간 동안 증가한 반면, L값은 저장기간 동안 감소하였다. 다만, 마찰 박피밤의 갈변정도가 칼날 박피밤보다 높게 나타났다. 과육경도는 마찰박피와 칼날박피에서 $-1^{\circ}C$ 처리구의 밤이 가장 높았으며, 당함량은 저장직후부터 감소하였으나 저장 24일째부터 당함량이 증가하는 경향을 나타내었다. 박피밤의 식미와 식감은 모든 처리구에서 저장기간이 늘어날수록 감소하였으며, 저장 15일 이후로 급격하게 감소하는 경향을 보였다. 따라서 위의 결과를 볼 때 마찰과 칼날 밤피밤의 품질차이는 나타나지 않았다. 하지만 $4^{\circ}C$와 $2^{\circ}C$에서 저장한 박피밤은 15일 이후 품질이 급격하게 감소한 반면 $-1^{\circ}C$에서 저장한 박피밤은 천천히 감소하여 품질을 유지하는데 효과적이었다. 또한 마찰 박피밤의 갈변을 줄일 수 있으면 고품질의 우수한 박피밤이 생산될 수 있을 것이다.

• Tribology and Lubricants
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• 제34권6호
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• pp.318-324
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• 2018

This study aims to visualize the friction and wear behaviors of metal coatings in real time. The main mechanism of wear is identified by observing all the processes in which wear occurs. The friction coefficients of the moments are monitored to confirm the relationship between the friction and wear characteristics of the coating. Thin Ag coatings, which are several hundred nanometers in thickness, are prepared by depositing Ag atoms on silicon substrates through a sputtering method. A pin-on-disk-type tribo-tester is installed inside a scanning electron microscope (SEM) to evaluate the friction and wear characteristics of the Ag coating. A fine diamond pin is brought into contact with the Ag coating surface, and a load of 20 mN is applied. The contact pressure is calculated to be approximately 15 GPa. The moments of wear caused by the sliding motion are visualized, and the changes in the friction characteristics according to each step of wear generation are monitored. The Ag coating can be confirmed to exhibit a wear phenomenon by gradually peeling off the surface of the coating on observing the friction and wear characteristics of the coating in real time inside the SEM. This can be explained by a typical plowing-type wear mechanism.