• 소성∙가공
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• 제18권8호
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• pp.607-616
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• 2009

There are three sub-processes associated with the assembly of the valve seat and cylinder head; heat fitting, cold fitting, and shrink fitting. In the heat fitting stage, the cylinder head is heated to a specified temperature and then squeezed toward the outer diameter of the valve seat. The cold fitting process cools the valve seat and safely squeezes it toward the inner diameter of cylinder head. However, these methods increased the installations & running cost and curtailed productivity. To address these problems, we analyzed the shrink fitting process using the contact pressure caused by fitting interference between the outer diameter of the valve seat and the inner diameter of the cylinder head. In this study, a closed form equation for predicting the contact pressure and fitting load is proposed. For quality control of the assembly line, principal factors of the shrink fitting process influenced in contact pressure were simulated by the FEM. Actual loads measured in the field showed good agreement with the results obtained by theoretical and finite element analysis.

• Korea-Australia Rheology Journal
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• 제13권3호
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• pp.125-130
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• 2001

Block copolymers of PC-b-PMMA (polycarbonate-b-polymethylmethacrylate) and PC -b-SAN (polycarbonate-b-(styrene-c-acrylonitrile)), were examined as compatibilizers for blonds of PC with SAN copolymer. The average diameter of the dispersed particles was measured with an image analyser, and the interfacial properties of the blonds were analysed with an imbedded fiber retraction (IFR) technique. The average diameter of dispersed particles and interfacial tension of the PC/SAN blends reached a minimum value when the SAN copolymer contained about 24 wt% AN. Interfacial tension and particle size were further reduced by adding compatibilizer to the PC/SAN blends. PC-b-PMMA was more effective than PC-b-SAN as a compatibilizer in reducing the average diameter of the dispersed particles and interfacial tension of PC/SAN blend. A direct proportionality between the particle diameter and interfacial tension was also observed. The interfacial properties of the PC/SAN blends were optimized by adding a block copolymer and using an SAN copolymer that had minimum interaction energy with PC.

• 한국입자에어로졸학회지
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• 제13권2호
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• pp.53-63
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• 2017

As semiconductor process was highly integrated, particle contamination became a major issue. Because particle contamination is related with process yields directly, particles with a diameter larger than half pitch of gate should be controlled. PBMS (Particle beam mass spectrometry) is one of powerful nano particle measurement device. It can measure 5~500 nm particles at ~ 100 mtorr condition in real time by in-situ method. However its usage is restricted to research filed only, due to its big device volume and high price. Therefore aperture changeable aerodynamic lenses (ACALs) which can control particle focusing characteristics by changing its aperture diameter was proposed in this study. Unlike conventional aerodynamic lenses which changes particle focusing efficiency when operating condition is changed, ACALs can maintain particle focusing efficiency. Therefore, it can be used for a multi-monitoring system that connects one PBMS and several process chambers, which greatly improves the commercialization possibility of the PBMS. ACALs was designed based on Stokes number and evaluated by numerical method. Numerical analysis results showed aperture diameter changeable aerodynamic lenses can focus 5 to 100 nm standard particles at 0.1 to 10 torr upstream pressure.

• 한국정보통신학회논문지
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• 제2권1호
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• pp.141-146
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• 1998

Recently, the computer vision such as part measurement, and product inspection is very popular to achieve the factory automation since the labor cost is dramatically increasing. In this paper, the diameter and the length of rope are measured by CCD camera which is orthogonally mounted on the ceiling. Two parameters which are the diameter and the length of rope are used to measure the weight of rope. If the weight of rope is reached to predetermined weight, the information is transmitted to PLC(programmable logic control) to cut the rope on the wheel. The cutting machine cuts the rope according to the information obtained from the CCD camera. To measure the diameter and length of rope on real time, the searching space for image segmentation is restricted the predetermined area according to the camera calibration position. Finally, to estimate the weight of rope, the knowledge base system which depends on the diameter, the length of rope, and weight relation between these information are constructed according to diameters of rope. This method contributes to achieve the factory automation, and reduce the production cost since the operators are unnecessary to measure the weight of rope by try-and-error method.

• Korea-Australia Rheology Journal
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• 제17권4호
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• pp.157-164
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• 2005

Hydrodynamic characteristic of surfactant drag-reducing flows is still not fully understood. This work investigated the temperature and diameter effect on hydrodynamic characteristic of cationic surfactant drag reducing flows in pipes. Solution of oleyl bishydroxyethyl methyl ammonium chloride (Ethoquad O/12), 900 ppm, as a cationic surfactant and sodium salicylate (NaSal), 540 ppm, as a counter-ion was tested at 12, 25, 40, and $50^{\circ}C$ in pipes with diameter of 13, 25, and 40 mm. Drag reduction effectiveness of this surfactant solution was evaluated in 25 mm pipe from 6 to $75^{\circ}C$. Rheological characteristic of this solution was measured by stress control type rheometer with cone-and-plate geometry. Scale-up laws proposed by previous investigators were used to evaluate the flow characteristic of the solution. It was found that this surfactant solution has clear DR capability until $70^{\circ}C$. Result of this work suggested that temperature has a significant influence in changing the hydrodynamic entrance length of surfactant drag reducing flows. From rheological measurement, it was found that the solution exhibits Shear Induced Structure at all temperatures with different degree of peak viscosity and critical shear rate.

• 한국기계가공학회지
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• 제18권2호
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• pp.22-28
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• 2019

In this study, we describe the mechanical design of the cylindrical workpiece inspection system which that can inspect the workpiece machined in the CNC lathe. The workpiece automatic measuring device is composed of a workpiece aligning mechanism, a workpiece diameter measuring mechanism, and a workpiece height measuring mechanism. If the workpiece machined on the CNC lathe is placed on the pedestal of the cylindrical workpiece inspection system, the workpiece aligning mechanism moves the workpiece to the diameter-measuring position and the height- measuring positions, and the diameter-measuring mechanism and the height- measuring mechanisms sequentially measure the diameter and the height of the workpiece. The cylindrical workpiece inspection system was designed and manufactured. The characteristic experiment was conducted to confirm the operation of the machine tool of the cylindrical workpiece inspection system. As a The result of the characteristic test shows that, the workpiece automatic measuring device operated safely.

• Journal of Korean Neurosurgical Society
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• 제61권2호
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• pp.243-250
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• 2018

Objective : To compare the morphometry of subaxial cervical spine between cerebral palsy (CP) and normal control. Methods : We retrospectively analyzed 72 patients with CP, as well as 72 patients from normal population. The two groups were matched for age, sex, and body mass index. Pedicle, lateral mass (LM), and vertebral foramen were evaluated using computed tomography (CT) imaging. Pedicle diameter, LM height, thickness, width and vertebral foramen asymmetry (VFA) were measured and compared between the two groups. Cervical dynamic motion, disc and facet joint degeneration were investigated. Additionally, we compared the morphology of LM between convex side and concave side with cervical scoliotic CP patients. Results : LM height was smaller in CP group. LM thickness and width were larger in CP group at mid-cervical level. In 40 CP patients with cervical scoliosis, there were no height and width differences between convex and concave side. Pedicle outer diameter was not statistically different between two groups. Pedicle inner diameter was significantly smaller in CP group. Pedicle sclerosis was more frequent in CP patients. VFA was larger in CP group at C3, C4, and C5. Disc/facet degeneration grade was higher in the CP group. Cervical motion of CP group was smaller than those of the control group. Conclusion : LM morphology of CP patients was different from normal population. Sclerotic pedicles and vertebral foramen asymmetry were more commonly identified in CP patients. CP patients were more likely to demonstrate progressive disc/facet degeneration. This data may provide useful information on cervical posterior instrumentation in CP patients.

• 원예과학기술지
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• 제33권6호
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• pp.812-819
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• 2015

Gladiolus is one of the most popular cut flowers in the world floral market and is highly attractive to consumers. The production of poor-quality gladiolus spikes is one of the most important hurdles to obtaining high prices for this crop. The main objectives of this study were to improve the quantitative characteristics of gladiolus spikes, to increase propagule production and to enhance chemical constituent levels in leaves to help improve plant growth. We performed foliar application of bioregulators, including polyamines (putrescine and spermine) and vitamins (ascorbic acid and thiamine), at different concentrations (0, 0.1, 0.4, 0.7 and 1 mM) to gladiolus plants at the three leaf, five leaf and slipping stages. Application of 1 mM putrescine was the most effective treatment, with prominent effects on economically important spike traits including spike length (55.53 cm), spike diameter (7.53 mm), florets per spike (13.99), first floret diameter (9.66 cm) and first floret weight (4.90 g), followed by spermine treatment. The 1 mM putrescine treatment also had positive effects on corm-associated traits including corm diameter and corm weight, with values of 4.57 cm and 26.16 g compared to 3.47 cm and 17.16 g in control plants, respectively. The contents of chemical constituents in leaves, including total chlorophylls ($8.06mg{\cdot}g^{-1}$), total carotenoids ($1.66mg{\cdot}g^{-1}$), total soluble sugars ($4.75 mg{\cdot}g^{-1}$) and phenolics ($0.89mg{\cdot}g^{-1}$) increased in response to foliar application of 1 mM putrescine compared to the control. Ascorbic acid and thiamine also had positive effects on various plant morphological traits and chemical constituents in leaves compared to control plants, but the growth-promoting effects of polyamines were more pronounced. Hence, applying polyamines to gladiolus leaves will help improve spike production and increasing propagule (cormel) yields.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.1059-1065
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• 2020

Demand for pressure sensors is increasing in various fields such as machinery, healthcare and medical care. A recent study is being conducted to create sensors that are more sensitive and have longer linear sections based on measurement principles. In this paper, a film-type sensor with a membrane structure was developed to measure the pressure distributed in the axial direction of a hot roll laminator. Performance of sensors was evaluated by resistance and durability according to membrane diameter. The resistance of the membrane sensor varies according to the contact state and contact area of the electrode. Therefore, the membrane diameter selection is important. Experiments showed the most pronounced variation in resistance under pressure at 8 mm in diameter of membrane. Reliability evaluation of sensors was carried out at room temperature and high temperature. The pressure on the sensor was pressurized 1000 times to measure the initial resistance and the resistance after the evaluation to analyze the change. Sensors showed stable results with low resistance changes of 5.15% and 6.27%, respectively. A large area sensor manufactured using the developed sensor also showed reliable results.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.2-2
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• 2011

Single-walled carbon nanotubes (SWNTs) have been considered as a promising candidate for nextgeneration electronics due to its extraordinary electrical properties associated with one-dimensional structure. Since diversity in electronic structure depends on geometrical features, the major concern has been focused on obtaining the diameter, chirality, and density controlled SWNTs. Despite huge efforts, the controlled synthesis of SWNTs has not been achieved. There have been various approaches to synthesize controlled SWNTs by preparation of homogeneously sized catalyst because the SWNTs diameter highly depends on catalyst nanoparticles size. In this study, geometrically controlled SWNTs were synthesized using designed catalytic layers: (a) morphologically modified Al2O3 supporting layer (Fe/Al2O3/Si), (b) Mo capping layer (Mo/Fe/Al/Si), and (c) heat-driven diffusion and subsequent evaporation process of Fe catalytic nanoparticles (Al2O3/Fe/Al2O3/Si). These results clearly revealed that (a) the grain diameter and RMS roughness of Al2O3 supporting layer play a key role as a diffusion barrier for obtaining Fe nanoparticles with a uniform and small size, (b) a density and diameter of SWNTs can be simultaneously controlled by adjusting a thickness of Mo capping layer on Fe catalytic layer, and (c) SWNTs diameter was successfully controlled within a few A scale even with its fine distribution. This precise control results in bandgap manipulation of the semiconducting SWNTs, determined by direct comparison of Raman spectra and theory of extended tight binding Kataura plot. We suggest that these results provide a simple and possible way for the direct growth of diameter, density, and bandgap controlled SWNTs by precise controlling the formation of catalytic films, which will be in demand for future electronic applications.