• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.230.1-230.1
• /
• 2016

본 연구에서는 Host-Dopant system 기반 적색 인광 OLED의 Emitting layer(EML)에서 doping 위치에 따른 특성 변화를 분석하였다. EML은 host 물질로 60 nm 두께의 CBP를 사용하고, 적색 발광을 위해 10 %의 $Ir(btp)_2$를 CBP의 Front, Middle, Back side에 각각 20 nm씩 doping하였다. 본 구조의 적색 인광 OLED는 current density, luminance, efficiency, EL spectrum 등을 통해 전기적, 광학적 특성 변화를 확인하였다. Front, Back side에 doping으로 인한 CBP의 Energy level이 3.6 eV에서 1.9 eV로 감소하여 각각 HTL/EML, EML/HBL의 경계에 carrier direct injection이 활성화 되었고, 이로 인한 charge balance의 저하를 확인하였다. EL spectrum결과 각 소자는 CBP의 618 nm 파장 외에도, 추가적으로 TPBi의 398 nm, NPB의 456 nm의 파장을 보였다. 이를 통해 doping 위치에 따라 exciton이 형성되는 recombination zone이 이동하고 있음을 확인하였고, Front side는 6 V의 인가전압에서는 발광 파장이 398 nm에서 높은 값을 보이나 8 V, 10 V, 12 V에서 618 nm에서 높은 값을 보이는 것으로 인가전압에 의해 recombination zone이 HTL쪽으로 이동되는 것 또한 확인하였다.

• Transactions of the Korean hydrogen and new energy society
• /
• v.7 no.1
• /
• pp.55-62
• /
• 1996

As an essential step for development of a duel injection hydrogen fueled engine which can obtain high thermal efficiency and power in overall operating range, performance and BFL(back fire limit) equivalance ratio in hydrogen fueled engine with external mixture are investigated. As the results, BFL equivalence ratio in hydrogen fueled engine with external mixture is approximately 0.7. It is deduced that controls of driving conditions are required in transient stage from external mixture type to inner injection type. And in order to increase thermal efficiency, it is also found that BFL equivalence ratio should be expanded as much as possible.

• Design & Manufacturing
• /
• v.13 no.1
• /
• pp.36-41
• /
• 2019

A large plastic molding requires an injection molding with a large clamping force. However, it could not be prepared in the manufacturing at any time. In order to solve the problem, the injection molding analysis study was conducted on the back cover of 55 inch LED TV. The study compared the case of applying the existing flow system such as hot runner, the improvement of the hot runner lay-out and the precise control of the gate operation time, From the results of using the improved flow system, it was found that the welding and the clamping force were considerably improved as compared with before the improvement. In particular, the clamping force was reduced by 50% compared with before the improvement.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.11a
• /
• pp.241-242
• /
• 2019

This technology is a water leak repair technology using composite materials of concrete structures that block leakage of structures by injecting rapid microcement into the face of underground concrete to block water and injecting flexible glycidylacrylate. Rapid micro cement system repair materials are mixed with fine fibers to improve the flexural sensitivity of the material and to form a layer that blocks stabilized water at the back of the structure by allowing rapid and tight spatial filling during injection with high cohesion The glycidylacrylate repair material can control the expansion rate, and the external stress also has the characteristic that the form of the material is not destroyed or separated, which can also be applied to vibrating induced structures that produce repetitive fatigue loads, and has an effective durability in saline, alkali, acid (chloric acid, sulfuric acid, nitric acid).

• The Korean Journal of Pain
• /
• v.10 no.1
• /
• pp.77-81
• /
• 1997

Background : We studied the effects of lumbar spinal root block (RB) prospectively in 21 patients who had suffered from low back pain with radiating pain even treated epidural steroid injection three times. Method : RB was performed under the fluoroscopic C-arm guide. When the needle was in correct position, we confirmed the needle placement and expected drug spreading by injection of contrast medium ($Isovist^{(R)}$-300, Sobering, Germany). Next 2% mepivacaine 1 ml mixed to 40 mg of Depomedrol was injected. Pain assessment was carried out 7 days after RB by numeric pain score regarding the pain just before RB was 10. Remained pain after RB was graded as excellent; 0-2, good; 3-5, bad; 6-8 and poor 9-10. Results : Mean age of the patients was 52.3 years. 38.1% and 47.6% of the patients showed excellent and goo dresults after RB, respectively. Conclusion : We concluded that RB is easy and safe procedure to perfirm and effective for the treatment of remnant pain following epidural steroid injection, especially in the patients who had spinal stenosis.

• Transactions of Materials Processing
• /
• v.17 no.5
• /
• pp.322-327
• /
• 2008

LGP is a key component of LCD back light unit because it determines brightness and sharpness of the display image. Usually, it has optical patterns fabricated on the bottom surface. These optical patterns convert point or line sources placed in the side of LGP to plane source at the top surface by changing the propagating direction of the incident light. In the present paper the LiGA-reflow method was applied to fabricate the LGP mold. Furthermore, the optical simulation considering the replication ratio of pattern height was applied to the pattern design. The optical simulation through systematic correction scheme was adopted to find the optimum distribution of pattern density. Finally, the stamper fabricated by this method was installed in the mold and LGP was produced by injection molding. As a result of luminance measurement for the final product, the average luminance and luminance uniformity was measured 3,180 nit and 84%, respectively. Consequently, the mold fabrication method using the LiGA-reflow and optical simulation(CAE) can save the expense and time compared with the existing fabrication methods(laser ablation and chemical etching).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.5
• /
• pp.91-96
• /
• 2009

The number of vehicles applied diesel engine are rapidly rising for fuel economy. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced emission regulation. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter by car makers but also in retrofit market. In this paper we discussed the optimization of active regeneration timing by comparing the fuel consumption from back pressure caused by PM loading and from active regeneration. The effects of back pressure of DPFs during PM loading, active regeneration condition and engine emission(PM) on additional fuel consumption are experimentally investigated and the proper regeneration timings according to DPF systems and fuel loss for 160,000km are determined.

• Journal of Korean Medicine Rehabilitation
• /
• v.31 no.3
• /
• pp.85-93
• /
• 2021

Objectives This study aims to compare the effect of an ultrasound on a guided group and an unguided group on Soyeom pharmacopuncture therapy on the facet joint in patients with acute low back pain caused by traffic accidents. Methods 21 patients with acute low back pain caused by traffic accidents from March 1, 2021 to May 31, 2021 were included in this study. The study was conducted as a retrospective study which analyzes the patient's medical records. 11 patients (Group A) received ultrasound guided Soyeom pharmacopuncture therapy and 10 patients (Group B) received unguided Soyeom pharmacopuncture therapy on the facet joint. Visual analogue scale (VAS) and Oswestry disability index (ODI) was used to evaluate improvements in functions and pain, and five point Likert scale to evaluate patient's satisfaction. Results Both groups showed a statistically significant decrease in the VAS and ODI on the 5th day of hospitalization. However, there was no statistically significant difference between the groups. Difference in the Likert scale between the groups was not statistically significant either. Conclusions We found that ultrasound guided Soyeom pharmacopuncture therapy on the facet joint showed similar efficacy compared with unguided Soyeom pharmacopuncture therapy at facet joint on acute low back pain patients caused by traffic accidents.

• Clinical Pain
• /
• v.20 no.2
• /
• pp.141-144
• /
• 2021

There are some cases of myofascial pain syndrome (MPS) with chronic upper back pain that does not respond to dry needling or trigger point injection, well-known treatments for MPS. A 67-year-old female developed a stabbing upper back pain with trigger point at left T7~8 levels 10 years ago. She complained of the pain with Numeral Rating Scale (NRS) 8 points. Myofascial release technique and trigger point injection had no effect. Under ultrasound guidance 20 ml of 1% lidocaine was injected into thoracic paravertebral space. Immediately, the pain was reduced to NRS 4 points. One week later, the second block was performed in the same way as the first, and the pain was reduced to NRS 2 points. The stabbing pain disappeared, and oral opioids were discontinued. Ultrasound guided thoracic paravertebral space block is an effective and safe treatment for refractory MPS with chronic upper back pain.

• The Korean Journal of Pain
• /
• v.21 no.3
• /
• pp.217-223
• /
• 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.