• 한국세라믹학회지
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• 제35권2호
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• pp.172-179
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• 1998

Valve lifter namely tappet is supported by lifter hole which is located upper side of camshaft in cylinder block transforms rotatic mvement of camshaft into linear movement and helps to open and shut the en-gine valve as an engine parts. The face of valve lifter which is continuously contacting with camshaft brings about abnormal wears such as unfair wear and early wear because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears therefore The valve lifter cast in me-tal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance As a results the optimum process conditions like injection condition mixture ratio and debonding process could be established. After sintering fine-sinered dual microstructure in which prior ${\alpha}$-SiC matches well with new SiC(${\beta}$-SiC) produced by reaction among the ${\alpha}$-SiC carbon and silicon was obtained. Based on the study it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100-1200 bending strength (300-350 Pa) fracture toughness(1.5-1.7 Mpa$.$m1/2) Through engine dynamo test-ing SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such as early fracture unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resis-tance relaibility and lightability.

• 한국기계가공학회지
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• 제20권5호
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• pp.135-141
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• 2021

As a trend of lightening automobiles and electronic products, several studies are currently underway to replace parts of metals with resins. In particular, heterojunctions between metals and resins are now under the spotlight. This study aims to evaluate the variation in bonding strength with process conditions when the polybutylene terephthalate (PBT) polymer is bonded to a specimen of the lightweight 6061 aluminum alloy (AL6061). Conditions of the bonding surface of the AL6061 specimen, the temperature of the injection mold, and the content of the glass fiber were considered to be process variables. Bonded specimens were manufactured for different values of these variables. Bonding strength tests were then performed on these specimens and variations were analyzed in their characteristics corresponding to those of the process conditions. Fractures in these specimens were assessed using scanning electron microscopy (SEM) to assess the fracture surface. This was then used to analyze the fracture shape and determine whether anodizing the specimen led to the development of cracks on the joint surface. Results of the above test indicated that while the surface condition of the specimen and the temperature of the injection mold significantly influenced the strength of bonding, the content of the glass fiber did not.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제39권4호
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• pp.188-192
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• 2013

Post-traumatic anterior open bite can occur as a result of broken balance among the masticatory muscles. The superior hyoid muscle group retracts the mandible downward and contributes to the anterior open bite. Denervation of the digastric muscle by injection of botulinum toxin type A (BTX-A) can reduce the power of the digastric muscle and help to resolve the post-traumatic anterior open bite. A patient with a bilateral angle fracture had an anterior open bite even after undergoing three operations under general anesthesia and rubber traction. Although the open bite showed some improvement by the repeated operation, the occlusion was still unstable six weeks after the initial treatment. To eliminate the residual anterior open bite, BTX-A was injected into the anterior belly of the digastric muscle. Following injection of BTX-A, the anterior open bite showed immediate improvement. Complication and relapse were not observed during follow-up. Long-standing post-traumatic open bite could be successfully corrected by injection of BTX-A into the anterior belly of the digastric muscle without complication.

• 터널과지하공간
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• 제31권1호
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• pp.41-51
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• 2021

치밀 저류층의 투과도 증진을 위해 개발된 수압파쇄 기술은 셰일가스와 같은 비전통자원과 심부지열 개발에 필수적인 기술 중 하나이다. 파쇄형태가 단순하고 파쇄효율이 좋지 않은 수압파쇄를 개선하기 위해 다양한 파쇄유체를 이용한 실험적 연구가 진행되었다. 물, N2, CO2 가스를 파쇄유체로 사용하여 치밀 암석에 대한 파쇄형태와 효율성을 분석하였다. 파쇄유체로 물을 일정 주입속도로 주입한 경우 순간적으로 압력이 상승하여 파쇄가 발생하였으나, 파쇄유체로 가스를 주입한 경우 서서히 압력이 증가되면서 물보다 낮은 파쇄압력을 보였다. 3D 단층촬영 기법을 이용하여 물과 가스 주입으로 생성된 균열을 관찰한 결과는 기존 공극부피 대비 파쇄 자극부피가 각각 5.71%(물), 12.72%(N2), 43.82%(CO2) 증가되었다. 또한 파쇄유체의 파쇄 효율성을 검정하기 위한 파쇄 전후 투과도 변화 실험에서는 가스 파쇄에 의해 증가되는 투과도 증가 값이 물을 이용한 파쇄보다 훨씬 높게 측정되었다. 파쇄 이후 인공균열의 생성과 주변응력에 의해 다시 균열이 닫히는 현상을 고려하여 생성된 인공균열에 구속압을 단계별로 증가시켜 투과도 변화를 측정하였다. 구속압이 2MPa에서 10MPa로 증가시켰을 경우 초기 투과도 대비 각각 89%(N2), 50%(CO2) 감소하였다. 본 연구는 가스파쇄기술이 수압파쇄보다 투과도 증진 효과가 크고 이후 주변 응력에 의한 투과도 감소가 적은 것으로 나타났다.

• 자원환경지질
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• 제47권3호
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• pp.247-254
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• 2014

불균질한 자연균열 저류층에서 암체의 압축률은 매우 작은 값을 가지는 반면에 균열의 압축률은 상대적으로 큰 값을 갖는다. 균열의 압축률을 포함한 유효 압축률을 고려하지 않을 경우에는 균열의 간극 변화로 인한 공극 부피의 변화를 반영할 수 없기 때문에 정확한 오일 회수를 예측할 수 없다. 본 연구에서는 기존의 연구들에서 암체의 압축률만을 고려하여 오일 회수를 분석했던 것과 달리, 암체와 균열의 압축률을 모두 고려한 유효 압축률을 적용해서 오일 회수량을 분석하였다. 폴리머 공법에서 균열의 압축률이 폴리머의 주입에 미치는 영향을 이해하기 위해, 폴리머의 분자량, 농도, 주입속도에 따른 오일 회수량을 분석하였다. 유효 압축률을 고려할 경우 폴리머 분자량, 농도, 주입속도가 높아질수록 유효 압축률을 고려하지 않은 경우가 고려한 경우보다 누적 오일 생산량이 높게 나타났다. 또한 공저 압력의 경우에도 유효 압축률을 고려하지 않은 경우가 고려한 경우보다 빠르게 급감하여 오일 생산량에 영향을 주는 것을 확인할 수 있다.

• Journal of Korean Neurosurgical Society
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• 제40권2호
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• pp.90-94
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• 2006

Objective : Acute vertebral burst fractures warrant extensive fixation and fusion on the spine. Osteoplasty [vertebroplasty with high density resin without vertebral expansion] has been used to treat osteoporotic vertebral compression fractures. We report our experiences with osteoplasty in acute vertebral burst fractures. Methods : Twenty-eight cases of acute vertebral burst fracture were operated with osteoplasty. Eighteen patients had osteoporosis concurrently. Preoperative MRI was performed in all cases to find fracture level and to evaluate the severity of injury. Preoperative CT revealed burst fracture in the series. The patients with severe ligament injury or spinal canal compromise were excluded from indication. Osteoplasty was performed under local anesthesia and high density polymethylmethacrylate[PMMA] was injected carefully avoiding cement leakage into spinal canal. The procedure was performed unilaterally in 21 cases and bilaterally in 7 cases. The patients were allowed to ambulate right after surgery. Most patients discharged within 5 days and followed up at least 6 months. Results : There were 12 men and 16 women with average age of 45.3[28-82]. Five patients had 2 level fractures and 2 patients had 3 level fractures. The average injection volume was 5.6cc per level Average VAS [Visual Analogue Scale] improved 26mm after surgery. The immediate postoperative X-ray showed 2 cases of filler spillage into spinal canal and 4 cases of leakage into the retroperitoneal space. One patient with intraspinal leakage was underwent the laminectomy to remove the resin. Conclusion : Osteoplasty is a safe and new treatment option in the burst fractures. Osteoplasty with minimally invasive technique reduced the hospital stay and recovery time in vertebral fracture patients.

• 대한두개안면성형외과학회지
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• 제17권3호
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• pp.154-157
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• 2016

Transient anisocoria is rare during blowout fracture reconstruction. We report a case of transient anisocoria occurring during medial blowout fracture reconstruction and review the relevant literature. A 54-year-old woman was struck in the face and was admitted for a medial blowout fracture of the left eye. During the operation, persistent bleeding occurred. To control this bleeding, a 1% lidocaine solution with 1:200,000 epinephrine was applied to the orbital wall with cotton pledgets. In total, 40 mL of local anesthetic was used for the duration of the operation. After approximately three hours of the surgery, the ipsilateral pupil was observed to be dilated, with sluggish response to light. By 3 hours after the operation, the mydriasis had resolved with normal light reflex. In conclusion, neurological and ophthalmologic evaluation must be performed prior to blowout fracture surgery. Preoperative ophthalmic evaluation is simple and essential in ruling out any preexisting neurologic condition. Moreover, surgeons must be aware of the fact that excessive injection of lidocaine with epinephrine for hemostasis during orbital wall surgery can result in intraoperative anisocoria. Anisocoria-related situations must be addressed in a proficient manner through sufficient understanding of the mechanism controlling the pupillary response to various stimuli.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.128-128
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• 2010

In this study, we investigated the evolution and reduction of the surface roughness during the high-speed chemical dry thinning process of Si wafers. The direct injection of NO gas into the reactor during the supply of F radicals from NF3 remote plasmas was very effective in increasing the Si thinning rate, due to the NO-induced enhancement of the surface reaction, but resulted in the significant roughening of the thinned Si surface. However, the direct addition of Ar and N2 gas, together with NO gas, decreased the root mean square (RMS) surface roughness of the thinned Si wafer significantly. The process regime for the increasing of the thinning rate and concomitant reduction of the surface roughness was extended at higher Ar gas flow rates. In this way, Si wafer thinning rate as high as $20\;{\mu}m/min$ and very smooth surface roughness was obtained and the mechanical damage of silicon wafer was effectively removed. We also measured die fracture strength of thinned Si wafer in order to understand the effect of chemical dry thinning on removal of mechanical damage generated during mechanical grinding. The die fracture strength of the thinned Si wafers was measured using 3-point bending test and compared. The results indicated that chemical dry thinning with reduced surface roughness and removal of mechanical damage increased the die fracture strength of the thinned Si wafer.

• 동의생리병리학회지
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• 제37권6호
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• pp.185-192
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• 2023

The purpose of this study is to analyze trends in domestic and international clinical research studies on pharmacopuncture treatment for fractures. We searched five online databases (PubMed, CNKI, RISS, KISS, and OASIS), and selected a total of 13 clinical research studies from Korea and China. Selected studies were analyzed according to publication year, subject, intervention, treatment method, evaluation scale, adverse event, risk of bias, etc. A total of 10 case studies and 3 randomized controlled trials were included. The study subjects were more often female, and the most common type of fracture was vertebral compression fracture. In Korea, herbal medicine preparations and bee venom were used for pharmacopuncture solution, whereas in China, both herbal medicine preparations and Western medicine preparations were used. All studies commonly used local acupoint needling, and in most cases, the treatment period for case study was less than 1 month, and the observation period of randomized controlled trials was diverse. The most frequently used evaluation scale was numeric rating scale, adverse events were mentioned in only three studies, and no adverse events were reported. Overall risk of bias of all included randomized controlled trials was judged "some concerns". According to this study, pharmacopuncture treatment for fractures was found to be relatively effective and safe, but research that complements the limitations of this study is needed.

• 대한족부족관절학회지
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• 제5권2호
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• pp.156-159
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• 2001

Unicameral bone cysts are benign solitary lesions that occur in the first two decades of life and with a greater frequency in the humerus and femur. The cyst is usually asymptomatic unless a fracture or impending fracture is present. The traditional method of treating unicameral cysts has been curettage with bone graft or steroid injection. Also, pathologic fractures in the calcaneus, unlike in other bones, are reported especially in the children to be nonexistent. In general, closed treatment was recommended for most of the calcaneal fractures in children, but suggested open reduction when joint displacement was severe. We report a case of displaced intraarticular fracture of the calcaneus with unicameral bone cyst in a child treated by classic curettage, allograft and open reduction with screw fixation.