• 정보저장시스템학회논문집
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• 제6권1호
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• pp.37-40
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• 2010

Fresnel lens is a kind of refractive optical lens with various advantages. It has nearly flat shaped optical lens that has small mass. Fresnel lens has number of applications in the compact optical systems. Recently, demands of high quality Fresnel lens for small size optical systems such as illumination units, compact imaging systems, display units, information storage systems, optical detecting units had increased rapidly. Conventional manufacturing process of high quality Fresnel lens is direct machining. However, it is not suitable for mass production because of high cost and long cycle time. Replication method can provide cost effective mass production process. However, there are various issues about replication of Fresnel lens. Fresnel lens has number of sharp blade shape prism. In the replication process, this blade shape causes defects that can affect optical efficiency. In this study, replication processes; injection molding process and UV imprinting process, were developed and evaluated using Fresnel lens that has maximum pattern height of $250\;{\mu}m$ and aspect ratio of 1.5.

• 동력기계공학회지
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• 제10권4호
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• pp.50-55
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• 2006

An efficient cooling system for a piston of an automotive engine is very important. Therefore a large capacity gasoline engine or diesel engine has adopted the direct injection cooling system to increase its cooling efficiency. In this direct cooling system, an cooling oil is injected to a piston directly using an oil jet and this cooling oil flows through an oil gallery inside the piston. Flow rate and injection accuracy of this cooling oil are very important because these are main factors that have influence on its efficiency. The purpose of this study is to understand the changes of flow characteristics with various curvatures and diameters of an outlet nozzle and to check whether engine oil enters into the oil gallery well or not. From this study, we found that secondary flow was formed in a curved part of jet due to centrifugal force and irregular flow pattern appeared at the jet outlet. This pattern has influence on flow characteristics of engine oil entering the gallery. These simulation results have a good agreement with experiments.

• 대한기계학회논문집A
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• 제26권4호
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• pp.631-636
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• 2002

It is necessary to improve mechanical and optical properties in the optical disk substrates as the information storage devices with high storage density using blue laser are being developed. Injection compression molding is regarded as the most suitable process to manufacture optical disk substrates for quality recording and read-out. In the present research, the effects of mold temperature and the insulation layer thickness on gapwise birefringence and the land-groove pattern were investigated. It was found that the values of the birefringence distribution were very sensitive to mold temperature history, and the level of birefringence reduced and, furthermore, the quality of replication was improved due to the insulation layer.

• 한국분무공학회지
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• 제25권4호
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• pp.154-161
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• 2020

A single spray plume is the basic unit of the entire spray plume and is an important factor in understanding the spray characteristics. However, since the multi-hole GDI injector has a narrow spray angle, the superposition of the spray plumes occurs severely. Therefore, the spray uniformity and the spray atomization characteristics of a single spray plume were analyzed in this study using a single-hole GDI injector. Five single-hole GDI injectors with different nozzle hole diameters were used in the experiment. The uniformity of the spray was evaluated through the analysis of the spray pattern images. In addition, the atomization characteristics were compared using the diameter distribution of the spray droplets obtained using PDPA. As a result, the larger diameter of the nozzle hole, the less uniformity of the spray, and the injection pressure did not have a significant effect on the spray uniformity. It is judged that the surface roughness of the injector has a greater effect on spray uniformity than the diameter of the nozzle hole. Also, the size of the spray droplets increased sharply when the diameter of the nozzle hole was 230 ㎛.

• 대한한의학회지
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• 제23권2호
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• pp.97-107
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• 2002

Objective : Acupuncture is a method used to treat many kinds of pain in oriental cultural medicine. Especially when hetero-segmental area acu-points are stimulated, the therapeutic effects of pain control have more critical properties than other methods of acupuncture. However, the mechanism of pain control by acupuncture is contradictory so far. The present study examined the effects of electroacupuncture (EA) applied to the acu-point of the hetero-segmental area on modulation of formalin-induced pain in Sprague-Dawley rats. Methods : In order to apply EA to acu-points in the plantar area of right forepaws, a pair of Teflon-coated stainless steel wires were implanted in HT 7 (Shin-Moon) and PC 7 (Dae-Reung) 7 days before the behavioral test. A behavioral test was performed by means of video camera after injection of 5% formalin ($50{\;}\mu\textrm{l}$) into the lateral plantar region of the left hind paw. EA was delivered by a constant DC current stimulator at 4~5 mA, 2 ms, and 10 Hz for 30 min. c-Fos protein expression was measured in the lumbar spinal cord at 2 hr and 4 hr after formalin injection. Results : Behavioral responses including favoring, flinching and biting occurred in the biphasic pattern, such as the 1st phase (0~5 min) and the 2nd phase (20~45 min) after formalin injection. However, EA (4~5 mA, 2 ms, 10 Hz) significantly inhibited the behavioral responses. Injection of formalin expressed c-Fos protein on the ipsilateral dorsal horn neurons in L3 - L5 and the expression was sustained more than 4 hrs after formalin injection. However, EA decreased c-Fos protein expression at dorsal horn neurons in the lumbar spinal cord till 4hrs after formalin injection. Conclusions : These results suggest that EA modulates formalin-induced pain and this inhibitory action may be elicited by the descending inhibitory system.

• The Korean Journal of Pain
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• 제21권3호
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• pp.217-223
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• 2008

Background: Lumbar transforaminal epidural injections (LTEIs) have been utilized in the treatment of radicular pain, and LTEIs have the advantage of target-specificity. However, there have not been enough studies on the contrast patterns in LTEIs with using fluoroscopy. The purpose of this study was to evaluate the spreading epidural contrast patterns that are seen during real-time fluoroscopic guided LTEIs. Methods: A total of 131 patients who underwent fluoroscopic guided LTEIs were studied. The inclusion criteria were those patients with low back pain and/or lower extremity pain that was caused by a herniated nucleus pulposus, lumbar spinal stenosis, failed back surgery syndrome, and herpes zoster-associated pain. We classified the contrast patterns in regard to the contrast flow spreading to the nerve root and/or the unilateral, bilateral or cylinderic type of epidural spreading on the AP view of the fluoroscopy and the ventral or dorsal epidural filling on the lateral view. In addition to the pattern analysis, we evaluated the range of contrast spreading from the cranial to the caudal epidural filling and the incidence of an intravascular flow pattern. Results: Epidural spreading was seen in 126 cases (96.2%) of the total patients through the nerve root. Ventral spreading occurred in 120 cases (95.2%). On the AP view, a nerve root with unilateral, bilateral and cylinderic epidural filling was noted for 108 (85.7%), 9 (7.1%) and 9 (7.1%) cases, respectively. The contrast spreading to vertebral segments was smaller for the patients with lumbar spinal stenosis and failed back surgery syndrome than for the other groups (P < 0.0083). The incidence of intravascular injection was 11.1% (14/126). Conclusions: LTEIs using fluoroscopic visualization provided excellent assessment of the ventral epidural filling as well as nerve root filling. However, unilateral epidural spreading was prominent for the LTEIs.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.213-216
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• 2007

LGP (light guide plate) of LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of the major components which affects the product quality of LCD. In the present study, the optical patterns of LGP(2.2") are manufactured by three different methods, namely, laser ablation, chemical etching and LiGA - reflow, respectively. The pattern surface images and roughness of mold and product were compared to check the optical characteristics. From the results of measurement the optical patterns fabricated by LiGA - reflow method showed the best geometric structure as intended in design and the lowest roughness among those.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.409-412
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• 1996

In this paper, the response characteristics of organic gases were investigated by using quartz crystal microbalance(Q.C.M) with different polymeric sensitive materials. The new linear parameter was discussed in order to develope gas sensing system using neural network and pattern recognition. We analyzed the response characteristics by the area of resonant frequency shift of quartz crystal, which mean affinities of organic gases for polymeric sensitive firm. The experimental results shows that the parameter made by the area of frequency shift which was linear with injection amount of organic gases has possibility to be used for pattern recognition and neural network. And they have different normalized pattern.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.240-243
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• 2009

Recently, many researches on the development of super-hydrophobic and anti-reflective surfaces have been concentrated on the fabrication of nano-patterned products. The nano-patterned mold is a key to replicate nano-patterned products by mass production techniques such as injection molding and UV molding. The present paper proposes fabricating nano-patterned mold with cost-effective method. The nano-pattern molded was fabricated by electroforming the anodic aluminum oxide template without E-beam lithography. The final mold with nano-patterns showed the pores with the diameter of $100{\sim}120$ nm and the height of 150 nm was fabricated.

• 핵의학기술
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• 제16권1호
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• pp.76-79
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• 2012

Purpose: This study was to evaluate usefulness of $^{99m}Tc$-MIBI scintimammography for dense breast by comparing concordance in test results between Tc-99m MIBI scintimammography and mammography whose effect was proved the most as an imaging tool depending on breast density and at the same time by examining limitation on evaluation depending on density of breast tissue. [Materials and Methods] In the period from December 2010 to July 2011, this study targeted 150 patients who took both of $^{99m}Tc$-MIBI scintimammography and mammography conducted by using breast gamma camera in this hospital. Breast density was classified to the four levels of pattern 1~4 based on the results of mammography. $^{99m}Tc$-MIBI scintimammography was conducted with the LCC, the RCC, the LMLO, and the RML one minute after intravenous injection of 99mTc-MIBI 7400 MBq (20 mCi) while analysis was made for concordance in test results of $^{99m}Tc$-MIBI scintimammography and mammography. [Results] Among the 150 patients, pattern 1 was found in 3 patients, pattern 2 in 44 patients, pattern 3 in 61 patients, and pattern 4 in 37 patients. There were 5 patients who showed the case where it was impossible to determine density of breast tissue due to foreign body inserted to breast. The concordance ratio of the results between $^{99m}Tc$-MIBI scintimammography and mammography was 95.5% for pattern 2, 95.1% for pattern 3 and 94.6% for pattern 4. This demonstrated that the concordance rate decreased according to the increase in breast density. [Conclusion] When there was limitation on evaluation of breast specific gamma imaging test results due to increased intake in breast tissue or surgical site, the concordance rate was 6.8% for pattern 2, 16.3% for pattern 3 and 18.9% for pattern 4. This demonstrated that the degree of limitation on evaluation of breast specific gamma imaging test results increased according to the increase in breast density.