• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.886-888
• /
• 2009

We fabricated flexible electronic paper display(EPD) by using toner particles on plastic (PC) substrate. We observed the relationship between contrast ratio and changes of rib structures. One is a fabrication of ribs on bottom substrate. The display with ribs on bottom substrate had higher contrast ratio about 46% than display with ribs on top substrate. The other is a change of density of rib. The less density of ribs fabricated, the higher the contrast ratio become.

• Archives of Plastic Surgery
• /
• v.43 no.6
• /
• pp.518-522
• /
• 2016

Background Enophthalmos may not appear immediately after trauma due to periorbital swelling in a blowout fracture, and preoperative measurements of enophthalmos cannot be used as a reliable guideline. It is important to predict the eventual final extent of enophthalmos in order to determine whether to perform surgery, and there have been several attempts to predict the degree of late enophthalmos using preoperative orbital volume. The purpose of this study is to investigate the correlation between the orbital volume ratio (OVR) with final enophthalmos and the palpebral fissure, and to find the OVR that induced 2 mm of enophthalmos in unilateral unoperated blowout fractures. Methods We retrospectively reviewed the medical records of 38 patients and divided them into 3 groups, determined by the fracture location. The relationships between the OVR and both the degree of enophthalmos and the palpebral fissure ratio (PFR) were assessed and, in particular, the OVR that induced 2 mm of enophthalmos was sought. Results Enophthalmos increased in proportion to the OVR, and there was a highly significant correlation between the increase in the OVR and the degree of enophthalmos (P<0.05). On the other hand, there was no correlation between OVR and PFR (P>0.05). The OVR that induced 2-mm enophthalmos was 112.18%. Conclusions The final degree of enophthalmos can be estimated by the preoperative measurement of OVR. Preoperative measurements of OVR can be used as quantitative values to predict the final degree of enophthalmos in pure blowout fractures.

• Archives of Plastic Surgery
• /
• v.32 no.6
• /
• pp.717-722
• /
• 2005

The authors evaluated 14 patients from July 1999 to February 2004 treated with total keloidectomy followed by postoperative radiation treatment, delivered within 24 hours or 24-36 hours after surgery. The total dose of radiation was 1200 cGy in three fractions for 4-5 days. Among the 14 patients treated, 8 patients were evaluated for following-up. The age range of these patients were from 22 to 44 years old, with the average age of 30 years. The site of keloid lesions consisted; 6 on the ear lobe, 5 on the anterior chest and 1 on the upper arm. The mean follow-up period was 29.9 months. The recurrence was evaluated with photogrammetric analysis and skin color analysis. The photogrammetric analysis was performed with planimetry for the comparison of the ratio of the reduced size to the preoperative size. The mean value of the relative size of reduction was 55% and the ratio of the ear lobes were greater than the ratio of the chests. The skin color analysis was performed with chromameter CR-300 for the analysis of color difference (E) between the surrounding normal skin and the lesion. The larger the recurred size was, similar to the original size, the larger the E value was, so the E value posses the probability of predictable objective tool of recurrence. Although verifying the effectiveness of radiation therapy following keloidectomy need more cases and long term follow-up evaluation, this therapeutic modality seems very effective in reducing the keloid size, especially in the ear lobe.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.889-892
• /
• 2004

We developed a high performance bottom contact, organic thin-film transistor (OTFT) array on plastic using a self-organized process. The effect of OTS treatment on the PVP gate insulator for the performance of OTFT on plastic has been studied The OTFT without OTS exhibited a field-effect mobility of 0.1 $cm^2$/Vs on/off current ratio of > $10^7$. On the other hand, OTFT with OTS, exhibited a field-effect mobility of 1.3 $cm^2$/Vs and on/off current ratio of>$10^8$.

• Journal of Korean Society of Water and Wastewater
• /
• v.22 no.1
• /
• pp.169-174
• /
• 2008

In this study a trickling filter system was developed by using polypropylene media and polypropylene nylon media that has recently been developed. The experiment analyzed an ability of water purification of the two plastic media and the effects of biomass on the final effluent. As recycling ratio increases, polypropylene nylon suspender showed higher efficiency by 20%; and, when media height was lengthened twice, efficiency increased about 10%. EPS and biomass increased in proportion to the increase of recycling ratio, and bound-TOC showed a similar trend with bound-EPS (extra-cellular polymeric substances) concentration.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.3 no.3
• /
• pp.46-51
• /
• 2004

Nowadays, plastic industry has needed to produce parts that require high precision and quality. To make a high precision and quality part, before injection molding, plastic material in investigated about their properties such as shrinkage, warpage, etc. In this study, experiments were conducted with PP(polypiopylene) to figure out shrinkage behavior according to three type aspect ratio of samples. The injection speed that affects on shear late, molecular orientation within plastic part was determined as main variable of experiment. As a result of experimental study, part shrinkage had a tendency to be decreased by increasing injection speed and aspect ratio of samples.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.10a
• /
• pp.92-97
• /
• 2004

The aim of this study is to estimate the strength of injection molded plastic stepped gear. We considered stepped gear as plate model which are fixed by two edges. While, on the other sides are free. Normal gear is calculated by Lewis formula which can be derived quite simply from the equation for the stress at the root of a cantilever beam. Stress ratio(step factor) is represented for the ratio of the bending stress of normal and the bending stress of stepped gear, and it is plotted by face width factor. This study is propose the step factor added in Dupont equation which are strength estimation of step gear

• Design & Manufacturing
• /
• v.2 no.2
• /
• pp.6-9
• /
• 2008

Injection molding is representative process of plastic production. Most of numerical analyses for injection molding have been based on the Hele Shaw's approximation: two-dimensional flow analysis. The present work covers numerical analyses of injection molding using three-dimensional solid elements. The accuracy of the analysis results has been verified through some numerical examples in comparison with the various conditions. In this study, moldflow software was used to analyze the cooling analysis. The results of cooling analysis and testing catapult were compared for plastic products.

• Design & Manufacturing
• /
• v.8 no.1
• /
• pp.40-44
• /
• 2014

As a rotating machine element, plastic gears are more and more widely used in such as industrial machine element, since plastic gear is lighter, higher wear-resistance, and higher vibration absorbing ability than metal gears. When operating plastic parts, tooth breakage and fatigue life shortened due to increasing number of applying load and tooth flank temperature rising, such that accuracy of plastic gears is divided from allowable range to cause vibration and noise. On this study, a internal plastic gears are developed which improved the filling balance molding process by a new injection mold structure. The new mold structure called HR3P(hot runner type 3plate mold). As the result from this studies, we obtained a very accurate roundness internal gears by using design of experiment.

• Transactions of Materials Processing
• /
• v.8 no.4
• /
• pp.393-398
• /
• 1999

The plastic instable flow phenomenon happens in practical forming process, I. e. upsetting, backward extrusion, piercing, indentation. And also, it is difficult to control precisely the shape and dimensions of forming process. It is found that instabilities of the process are mainly connected with imperfections in the lubrication, billet eccentricity, inclined punch alignment. In view of the direct relationship between instable material flow and quality defects of the products and for better control of forming operation, we should necessarily find out their phenomena. In this study, we introduced the friction disturbance due to inclined punch angle. Analysis of upset forging is carried out using the rigid plastic FEM and slab method with eccentricity. Also, we considered the buckling parameters of billet with the large aspect ratio in upset forging.