• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.774-778
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• 2004

The atomization process of a circular $SF_{6}$ liquid jet issued into an otherwise quiescent, high-pressure $N_2$ gas was observed to explore the breakup mechanism of liquid ligaments involved in turbulent atomization. Both liquid and gas temperatures were fixed at a room temperature but the gas pressure was elevated to more than twice the critical pressure of $SF_{6}$. Therefore, the liquid surface was in a thermodynamic state close to a critical mixing condition with suppressed vaporization. Since the surface tension and the surface gas density approach zero and the surface liquid density, respectively, phenomena equivalent to those which would appear when a very high speed laminar flow of water were injected into the atmospheric-pressure air can be observed by issuing $SF_{6}$ liquid at low speeds in micro-gravity environment which avoid disturbances due to gravity forces. The instability ob near-critical mixing surface jet was quantitatively characterized using a newly developed device, which could issue a very small amount of $SF_{6}$ liquid at small constant velocity into a very high-pressure $N_2$ gas.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.251-253
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• 2017

Prefilming air blast 연료노즐의 다상유동 해석을 수행하였다. 연료가 미립화되는 과정을 관찰하였으며 liquid film의 두께와 속도를 계산하였다. Slot에서 분사된 연료는 prefilmer surface에서 얇은 액막을 형성한 후 연료노즐 lip에서 액적으로 분열되었다. 또한 계산된 liquid film의 두께와 속도를 경계조건으로 하여 반응유동장 해석을 수행하였다. 분사된 액적은 venturi throat를 지나면서 기화되었고 연료노즐 하류에 반응영역이 형성되어 안정적으로 보염이 이루어졌다.

• 대한족부족관절학회지
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• 제2권1호
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• pp.6-12
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• 1998

Many surgical procedures have been described for the treatment of chronic lateral instability of the ankle. Tenodesis procedures using peroneus brevis tendon is traditionally common among them. Recently, the modified Brostrom anatomic procedure, that is, tightening the stretched out lateral ligaments to restore their norma] anatomy without the use of supplemental tissues and then suturing the lateral portion of the extensor retinaculum to the distal fibula over the ligament repair. has been gaining in popularity. We have reviewed 6 of 10 consecutive cases at an average of 17 months after modified Brostrom procedure. An excellent or good result was achieved in 5 cases, all of which had improved mechanical stability as measured radiographically. One case that had an unsatisfactory result was in patient who had had a previous Evans' operation. So, we believed that the modified Brostrom procedure is an excellent treating method for chronic lateral instability of the ankle.

• 대한족부족관절학회지
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• 제18권4호
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• pp.217-221
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• 2014

Fracture and fracture-dislocation of the ankle may be caused by a variety of mechanisms. In addition to the fracture, injury of soft tissue such as ligaments, tendons, nerves, and muscles may occur. Among these, tibialis posterior tendon injury is difficult to identify due to swelling and pain at the fracture site. There is no clear finding in radiological examination, therefore, it is found during surgery. In this case, irreducible fracture-dislocation of the ankle due to tibialis posterior tendon interposition was observed after the primary operation. The authors obtained satisfactory results in performance of a secondary operation assisted with arthroscopy.

• 한국지능시스템학회논문지
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• 제22권3호
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• pp.347-352
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• 2012

본 논문에서는 보행 로봇을위한 트러스 구조의 로봇 발 메커니즘을 제시한 후, 제시된 로봇 발 메커니즘의 특성을 분석하였다. 제시된 로봇 발 메커니즘은인간의 발의 구조적인 특징을 관찰하여 모델링 되었다. 특히, 인간의 발에 사용되고 있는 뼈대는 트러스로 나타내었고, 뼈대에 연결되어 있는 다양한 인대는 간단한 강성 요소로서 나타내었다. 따라서 이러한 로봇 발은 보행 로봇이 발걸음을 옮기는 과정에서 발에 작용되는 충격을 완화시킬 수 있는 장점을 갖는다. 결과적으로, 제안된 로봇 발 메커니즘은 보행로봇의 보행피로를 줄이는데 기여할 수 있다.

• Macromolecular Research
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• 제15권3호
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• pp.205-210
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• 2007

Collagen is the major structural protein of connective tissues. It can be used as a prosthetic biomaterial applicable to artificial skin, tendon, ligaments, and collagen implants. The objective of this study is to investigate the possibility of realizing wound dressing medical products by the synthesis of composite materials with collagen and a biodegradable polymer, PLLA, via a surface modification process. Type I collagen was obtained from pig skin by a separation process. The structural characteristics of the extracted collagen were confirmed by SDS-polyacrylamide (PAcr) gel electrophoresis (PAGE) and FTIR. Also, PLLA-g-PAcr was synthesized by the radical polymerization of acrylamide initiated by AIBN in the presence of PLLA. The surface of PLLA was modified by the presence of the acrylamide residues. The structural characteristics of the copolymer were analyzed by FTIR, $^1H-NMR$ and contact angle measurements. The water uptake and WVTR of the collagen/PLLA-g-PAcr composite tended to increase with increasing collagen concentration and with decreasing EDC concentration.

• Advances in biomechanics and applications
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• 제1권1호
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• pp.67-76
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• 2014

Bone properties are one of the key components when constructing models that can simulate the mechanical behavior of a mandible. Due to the complexity of the structure, the tooth, ligaments, different bones etc., some simplifications are often considered and bone properties are one of them. The objective of this study is to understand if a simplification of the problem is possible and assess its influence on mandible behavior. A cadaveric toothless mandible was used to build three computational models from CT scan information: a full cortical bone model; a cortical and cancellous bone model, and a model where the Young's modulus was obtained as function of the pixel value in a CT scan. Twelve muscle forces were applied on the mandible. Results showed that although all the models presented the same type of global behavior and proximity in some locations, the influence of cancellous bone can be seen in strain distribution. The different Young's modulus defined by the CT scan gray scale influenced the maximum and minimum strains. For modeling general behavior, a full cortical bone model can be effective. However, when cancellous bone is included, maximum values in thin regions increase the strain distribution. Results revealed that when properties are assigned to the gray scale some peaks could occur which did not represent the real situation.

• 대한족부족관절학회지
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• 제23권1호
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• pp.1-5
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• 2019

Surgical treatment to restore stability in the ankle and hindfoot and prevent further degenerative changes may be necessary in cases in which conservative treatment has failed. Anatomical direct repair using native ligament remnants with or without reinforcement of the inferior retinaculum is the so-called gold standard operative strategy for the treatment of lateral ankle instability. Non-anatomical lateral ligament reconstruction typically involves the use of the adjacent peroneus brevis tendon and applies only those with poor-quality ligaments. On the other hand, anatomic reconstruction and anatomic repair provide better functional outcomes after the surgical treatment of chronic ankle instability patients compared to a non-anatomic reconstruction. Anatomical reconstruction using an autograft or allograft applies to patients with insufficient ligament remnants to fashion direct repair, failed previous lateral ankle repair, high body mass index, or generalized ligamentous laxity. These procedures can provide good-to-excellent short-term outcomes. Arthroscopic ligament repair is becoming increasingly popular because it is minimally invasive. Good-to-excellent clinical outcomes have been reported after short and long-term follow-up, despite the relatively large number of complications, including nerve damage, reported following the procedure. Therefore, further investigation will be needed before widespread adoption is advocated.

• Archives of Plastic Surgery
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• 제48권2호
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• pp.158-164
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• 2021

Background In lower lateral cartilage (LLC) surgery, cephalic trimming poses risks for the collapse of the internal and external nasal valves, pinched nose, and drooping deformity. The cephalic lateral crural advancement (CLCA) technique presented herein was aimed at using a flap to increase nasal tip rotation and support the lateral crus, in addition to the internal and external nasal valves, by avoiding grafts without performing excision. Methods This study included 32 patients (18 female and 14 male) and the follow-up period for patients having undergone primer open rhinoplasty was 12 months. The LLC was elevated from the vestibular skin using the CLCA flap. A cephalic incision was performed without cephalic trimming. Two independent flaps were formed while preserving the scroll ligament complex. The CLCA flap was advanced onto the lower lateral crus while leaving the scroll area intact. The obtained data were analyzed retrospectively. Results The mean age of the patients was 31.6 years (range, 20-51 years). The Rhinoplasty Outcome Examination scores after 12 months varied from 90 to100 points, and 93% of patients reported perfect satisfaction. At a 1-year follow-up, the patients' nasal patency (visual analogue scale) rose from 4.56±1.53 (out of 10) to 9.0±0.65 (P<0.001). Conclusions The CLCA flap led to better nasal tip definition by protecting the scroll area, increasing tip rotation, and supporting the internal and external nasal valves without cephalic excision.

• 대한정형외과학회지
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• 제56권5호
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• pp.445-449
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• 2021

슬관절내 삽입성 골낭종은 주로 십자인대의 골 부착부에 작은 낭종의 형태를 보이며, 보통 증상과 관련은 없는 것으로 알려져 있다. 저자들은 31세 남자의 슬관절에서 통증이 유발된 후방십자인대 대퇴 부착부 거대 삽입성 골낭종을 진단하고, 소파술과 골시멘트 충진술로 좋은 결과를 얻었기에 보고하고자 한다.