• Korean Chemical Engineering Research
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• 제62권2호
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• pp.191-199
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• 2024

A study was conducted on a tubular heat exchanger to improve its heat transfer rate by using a novel baffle plate design with discontinuous swirling patterns. The design consisted of perforated baffle plates with rectangular air deflectors positioned at varying angles. The tubes in the heat exchanger were arranged in a consistent alignment with the airflow direction and exposed to a uniform heat flux on their surfaces. Each baffle plate included sixteen deflectors inclined at the same angle and arranged in a clockwise pattern. This arrangement induced a swirling motion of the air inside a circular duct where the heated tubes were located, leading to increased turbulence and improved heat transfer on the tube surfaces. The spacing between the baffle plates was adjusted at different pitch ratios, and the Reynolds number was controlled within a range of 16,000 to 29,000. The effects of pitch ratios and inclination angles on the heat exchanger's performance were analyzed. The results indicated that using a baffle plate with rectangular deflectors inclined at 30° and a pitch ratio of 1.2 resulted in an average increase of 1.29 in the thermal enhancement factor.

• 전자공학회논문지
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• 제54권7호
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• pp.81-89
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• 2017

요동이 존재하는 환경에서, 요동 측정 오차에 의한 성능 저하를 극복하기 위한 신호처리 방식의 자동초점(Autofocus, AF) 기법의 적용은 필수적이다. 본 논문에서는 스퀸트 모드에서 획득한 합성 개구면 레이다 데이터에 역투영 알고리즘(back-projection algorithm, BPA)으로 영상을 형성하고, AF를 효과적으로 적용하기 위한 방식을 연구하였다. 자동 초점 기법의 효과적인 적용을 위해 BPA 영상을 회전한 상태로 형성하는 방식을 제안하며, 이때 필요한 후처리 도플러 위치 정렬 함수를 유도하였으며, 비행시험을 통해 획득한 SAR(Synthetic Aperture Radar, SAR) 원시 데이터에 적용하여 성능 개선을 확인함으로써, 실 데이터에서도 유효한 방식임을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.881-887
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• 2005

A total knee replacement is an extremely 'position-sensitive' operation; a malposition or a malalignment of the components will lead to a breakage of the component, a fracture around the knee prosthesis, and the limitation of range of the motion, etc. In a conventional total knee replacement, surgeons have to select an appropriate prosthesis according to the shape of the surgical region. A wrong selection may give rise to side effects or to need re-operation. Nevertheless, it is so difficult to choose the most proper prosthesis out of various kinds of prosthesis. This paper presents a surgical planning system for the total knee replacement with an operation simulating method in order to determine the parameters for the total knee replacement operation. We select an alignment axis and a resection angle as major operation parameters in the total knee replacement operation, and introduce the method to determine the major operation parameters with the operation simulator we developed. The simulator is used to determine operation parameters for optimized operations, to select the most appropriate prosthesis, and to analyze the prospective problems of the operation.

• 대한족부족관절학회지
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• 제10권1호
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• pp.88-91
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• 2006

Purpose: To evaluate the effect on clinical course of heterotopic ossification of distal tibiofibular syndesmosis after ankle fractures. Materials and Methods: From June 2001 to May 2004, we found nine cases of heterotopic ossification of distal tibiofibular syndesmosis after ankle fractures. There were 8 male patients and 1 female patient; their mean age was 42 years old. There were 6 Weber type B and 2 Weber type C fractures, and there is 1 case with posterior malleolus fracture only. Among them, 8 ankle fractures were operated. Follow up period was averaged for 14 months. We were able to review radiographs at initial injury and to review clinical menifestation and radiographs at last follow up. We used an ankle-hindfoot scoring system of AOFAS which combined symptom, function and alignment with maximum score of 100 point. Results: In all cases ankle dorsiflexion and plantarflexion were not significantly different from that of the contralateral side. The patients who had developed heterotopic ossification in distal tibiofibular syndesmosis had a similar functional score. The mean ankle-hind foot score was 94 points. Conclusion: We concluded that the heterotopic ossification of distal tibiafibular syndesmosis after ankle fractures had little effect on clinical course and range of motion of ankle joint.

• 대한치과교정학회지
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• 제52권6호
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• pp.451-460
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• 2022

Moebius syndrome (MBS) is a congenital neurologic disorder that causes cranio-facial abnormalities. It involves paralysis of the VI and VII cranial nerves and causes bilateral or unilateral facial paralysis, eye movement disorder, and deformation of the upper and lower limbs. The orofacial dysfunctions include microstomia, micrognathia, hypotonic mimetic and lip muscles, dental enamel hypoplasia, tongue deformity, open bite or deep overbite, maxillary hypoplasia, high arched palate, mandibular hyperplasia or features indicating mandibular hypoplasia. This case report presents a 7-year-old male patient who was diagnosed with MBS at the age 2 years. The patient displayed typical clinical symptoms and was diagnosed with Class II malocclusion with a large overjet/overbite, tongue deformity and motion limitation, and lip closure incompetency. Treatment was initiated using a removable appliance for left scissor bite correction. After permanent tooth eruption, fixed appliance treatment was performed for correction of the arch width discrepancy and deep overbite. A self-ligation system and wide-width arch form wire were used during the treatment to expand the arch width. After 30 months of phase II treatment, the alignment of the dental arch and stable molar occlusion was achieved. Function and occlusion remained stable with a Class I canine and molar relationship, and a normal overjet/overbite was maintained after 9.4 years of retainer use. In MBS patients, it is important to achieve an accurate early diagnosis, and implement a multidisciplinary treatment approach and long-term retention and follow-up.

• 국제물리치료학회지
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• 제11권3호
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• pp.2102-2106
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• 2020

Background: Static hamstring stretching exercises have been widely used to improve flexibility of the hamstring muscles. However, few studies have examined the influence of standing static hamstring stretching (e.g., jack-knife stretching) on movements of the lumbopelvic-hip complex. Objectives: To examine the short-term effects of jack-knife stretching on movements of the lumbopelvic-hip complex. Design: Case series. Methods: Fourteen participants with hamstring tightness (8 male, 6 female) were recruited. Participants performed jack-knife stretching for 150 s. Before and after stretching, participants performed the finger-to-floor distance (FFD), sit and reach (SRT), active knee extension (AKE), passive straight leg raising (PSLA), and active straight leg raising (ASLR) tests as well as pelvic tilt while standing to identify the effects of stretching. Results: There were significant improvements in the FFD, SRT, AKE, PSLA, and ASLR tests after stretching. However, pelvic tilt angle while standing did not significantly change. Conclusion: Jack-knife stretching can be a useful exercise to improve flexibility of the hamstring muscles, but not pelvic alignment while standing.

• 한국체육학회지인문사회과학편
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• 제56권5호
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• pp.665-677
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• 2017

이 연구는 U-12 유소년 축구선수를 대상으로 운동수행력과 의학적 평가를 상세히 분석한 후에 축구를 통한 운동수행력의 변화 및 의학적 문제점을 파악하는데 그 목적이 있다. 연구대상은 유소년 축구클럽에 참여하고 있는 초등학교 선수를 유소년 축구선수 집단(Youth football players group; YFG, n=15; $11.2{\pm}0.9$ 세)과 축구를 하지 않는 건강한 일반 유소년을 통제 집단(Control group; CON, n=15; $11.5{\pm}0.6$ 세)으로 각각 분류하여 운동수행력(건강관련 체력, 운동관련 체력, 기능적 움직임 및 동적 균형) 및 의학적 평가(하지정렬, 관절가동범위 및 도수근력검사)를 측정하였다. 왕복 오래달리기, 50-m 달리기, 눈 감고 외발서기, 능동적 하지직거상, 회전 안정성 및 비주측의 종합점수는 CON과 비교해서 YFG에서 긍정적인 결과를 보였다. 하지만, 하지정렬에서 주측 및 비주측의 Q각, 관절가동범위에서 비주측의 발목관절 발등굽힘, 주측 및 비주측의 발목관절 발바닥굽힘, 도수근력검사에서 주측의 엉덩관절 폄 및 벌림, 무릎관절 굽힘 및 폄, 비주측의 무릎관절 굽힘 및 폄은 CON과 비교해서 YFG에서 부정적인 결과를 초래하였다. 따라서 이 연구에서 U-12 유소년 축구선수는 부분적으로 운동수행력은 우수하게 나타났지만, 의학적 평가에서는 부정적인 결과를 확인하였다.

• 대한족부족관절학회지
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• 제15권2호
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• pp.51-57
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• 2011

Pilon fractures involving distal tibia remain one of the most difficult therapeutic challenges that confront the orthopedic surgeons because of associated soft tissue injury is common. To introduce and describe the diagnosis, current treatment, results and complications of the pilon fractures. In initial assessment, the correct evaluation of the fracture type through radiographic checkup and examination of the soft tissue envelope is needed to decide appropriate treatment planning of pilon fractures. Even though Ruedi and Allgower reported 74% good and excellent results with primary open reduction and internal fixation, recently the second staged treatment of pilon fractures is preferred to orthopedic traumatologist because of the soft tissue problem is common after primary open reduction and internal fixation. The components of the first stage are focused primarily on stabilization of the soft tissue envelope. If fibula is fractured, fibular open reduction and internal fixation is integral part of initial management for reducing the majority of tibial deformities. Ankle-spanning temporary external fixator is used to restore limb alignment and displaced intraarticular fragments through ligamentotaxis and distraction. And the second stage, definitive open reduction and internal fixation of the tibial component, is undertaken when the soft tissue injury has resolved and no infection sign is seen on pin site of external fixator. The goals of definitive internal fixation should include absolute stability and interfragmentary compression of reduced articular segments, stable fixation of the articular segment to the tibial diaphysis, and restoration of coronal, transverse, and sagittal plane alignments. The location, rigidity, and kinds of the implants are based on each individual fractures. The conventional plate fixation has more advantages in anatomical reduction of intraarticular fractures than locking compression plate. But it has more complications as infection, delayed union and nonunion. The locking compression plate fixation provides greater stability and lesser wound problem than conventional implants. But the locking compression plate remains poorly defined for intraarticular fractures of the distal tibia. Active, active assisted, passive range of motion of the ankle is recommended when postoperative rehabilitation is started. Splinting with the foot in neutral is continued until suture is removed at the 2~3 weeks and weight bearing is delayed for approximately 12 weeks. The recognition of the soft tissue injury has evolved as a critical component of the management of pilon fractures. At this point, the second staged treatment of pilon fractures is good treatment option because of it is designed to promote recovery of the soft tissue envelope in first stage operation and get a good result in definitive reduction and stabilization of the articular surface and axial alignment in second stage operation.

• Archives of Plastic Surgery
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• 제48권1호
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• pp.69-74
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• 2021

Background In inferomedially rotated zygomatic fractures sticking in the maxillary sinus, it is often difficult to achieve complete reduction only by conventional intraoral reduction. We present a new intraoral reduction technique using a Kirschner wire and its clinical outcome. Methods Among 39 inferomedially impacted zygomatic fractures incompletely reduced by a simple intraoral reduction trial with a bone elevator, a Kirschner wire (1.5 mm) was vertically inserted from the zygomatic body to the lateral orbital rim in 17 inferior-dominant rotation fractures and horizontally inserted to the zygomatic arch in nine medial-dominant and 13 bidirectional rotation fractures. A Kirschner wire was held with a wire holder and lifted in the superolateral or anterolateral direction for reduction. Following reduction of the zygomaticomaxillary fracture, internal fixation was performed. Results Fractures were completely reduced using only an intraoral approach with Kirschner wire reduction in 33 cases and through an additional lower lid or transconjunctival incision in six cases. There were no surgical complications except in one patient with undercorrection. Postoperative 6-month computed tomography scans showed complete bone union and excellent bone alignment. Four patients experienced difficulty with upper lip elevation; however, these problems spontaneously resolved after manual tissue lump massage and intralesional steroid (Triamcinolone) injection. Conclusions We completely reduced infraorbital rim fractures, zygomaticomaxillary buttresses, and zygomaticofrontal suture fractures in 84% of patients through an intraoral approach alone. Intraoral Kirschner wire reduction may be a useful option by which to obtain effective and powerful reduction motion of an inferomedially rotated zygomatic body.

• 천문학회보
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• 제36권2호
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• pp.91-91
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• 2011

The passage of the interplanetary discontinuity (i.e., sudden increases in the solar wind speed, density, and IMF strength) was detected by ACE near GSE (x, y, z) ~ (222, -36, 3) Re upstream of Earth around 22:48 UT on November 24, 2008. About 55 min later, this solar wind discontinuity was observed by Geotail near GSE (x, y, z) ~ (23, 18, -7) Re in front of Earth's bow shock. From the propagation time of the solar wind discontinuity between ACE and Geotail, it is expected that the discontinuity front is aligned with the Parker spiral and strikes the postnoon dayside magnetopause first. Using coordinated multi-point measurements (THEMIS and GOES) at or in geosynchronous orbit, we observed a tailward propagating sudden impulse (SI), excited by the interplanetary discontinuity, around 23:50 UT with its front retaining alignment similar to that of solar wind discontinuity. The SI event appears a negative-then-positive variation in the H component at high latitude Chokurdakh (CHD: MLAT ~ 64.7 deg) in the prenoon sector, which is opposite sense of normal SI event. During the positive deflection at CHD, the SuperDARN Hokkaido radar detected the downward motion of the ionosphere, implying westward electric field enhancement, at subauroral latitudes near CHD meridian. In our study we will discuss magnetospheric and ionospheric responses to the passage of the solar wind discontinuity using multi-point observations in space and on the ground.