• 전자공학회논문지 IE
• /
• 제43권3호
• /
• pp.34-40
• /
• 2006

일반적으로 유체나 연료 공급 장치는 모터를 제어하기 위한 특별한 센서가 필요하고, 센서를 부착하기 위한 보조 장치와 부착하기 위한 공간이 필요하다. 또한 신호선 및 기타 배선 등이 필요하여 어려운 점이 따르게 된다. 본 논문에서는, 불편함과 문제점을 해결하기 위하여 홀센서를 이용한 제어시스템을 제안하였고, 시스템의 제어원리는 모터 동작 단계에 따라 전류흐름에 차이가 발생한다는 것을 이용하였다. 또한 제어 시스템이 우수할 뿐만 아니라 센서 설치에 따른 고장을 줄일 수 있었고, 재료비 및 인건비를 절감할 수 있다. Auto-Pumping 시스템은 Soft-Ware적응용을 통해 모든 유체 공급 시스템에 적용할 수 있으며, 차후에 시스템을 이용한 여러 종류의 장치를 개발할 수 있으리라 본다.

• Journal of Power Electronics
• /
• 제16권1호
• /
• pp.84-92
• /
• 2016

Compared with Si MOSFETs, the GaN FET has many advantages in a wide band gap, high saturation drift velocity, high critical breakdown field, etc. This paper compares the electrical properties of GaN FETs and Si MOSFETs. The soft-switching condition and power loss analysis in a flyback-forward high gain DC/DC converter with a GaN FET is presented in detail. In addition, a comparison between GaN diodes and Si diodes is made. Finally, a 200W GaN FET based flyback-forward high gain DC/DC converter is established, and experimental results verify that the GaN FET is superior to the Si MOSFET in terms of switching characteristics and efficiency. They also show that the GaN diode is better than the Si diode when it comes to reverse recovery characteristics.

• Archives of Reconstructive Microsurgery
• /
• 제20권2호
• /
• pp.108-112
• /
• 2011

Purpose: Gracilis muscle free flap transplantation is chosen in the medium sized soft tissue defect and bone exposure from trauma and chronic osteomyelitis in the lower extremity. We set a study to search for gracilis free flaps to know whether symptoms were cured or recurred in patients that have passed over 10 years from flap transplantation. Materials and Methods: From August 1995 through September 2010, we have performed 28 cases of gracilis muscle free flap in the lower extremities. Ever since no case visited to demand any discomfort, breakdown or recurrence in the flap site on outpatient basis. We made a telephone call to patients or relatives documented in the medical record and only 2 cases visited outpatient department and 9 cases postponed the visit who satisfied with the final result but 17 cases had wrong telephone numbers. Causes, area of lower extremity, recipient vessels in the lower extremity, condition of the donor thigh and overall satisfaction of the flap transplantation in activities of daily living were investigated and written down in the medical record. Results: 11 cases were reviewed after average postoperative 13.7 years. Gracilis muscle flaps were not break down at the recipient site in all cases. The wound of donor thigh wound healed good and overall activities of daily living was satisfied in all cases. Conclusion: Gracilis muscle flaps which had performed and followed up average 13.7 years revealed confident in the medium sized soft tissue defect and bone exposure from trauma and chronic osteomyelitis in the lower extremity.

• 전자공학회논문지A
• /
• 제33A권4호
• /
• pp.106-111
• /
• 1996

Schottky diodes are fabricated on laser annealed and unannealed polysilicon substrate and their electrical characteristics are studied and analyzed. Current of laser annealed devices are larger than that of unannealed devices because of grain growth, decrease of grain boundary and trap density, lowering of grain boundary barrier height, decrease of dopant segregation. At low forward bias (<0.7V), currents of unanealed devices are larger. Soft breakdown voltages of laser annealed devices are larger than that of unannealed devices.

• 대한족부족관절학회지
• /
• 제17권4호
• /
• pp.257-263
• /
• 2013

Open reduction and internal fixation is currently considered as a gold standard of treatment in most of the intra-articular calcaneal fractures. Among various different approaches, extensile lateral approach is the most popular since it provides good exposure to the subtalar joint. However, wide skin incision followed by extensive soft tissue dissection leading to increased risk of wound breakdown is the most serious drawback. Sinus tarsi approach, a minimal invasive technique to approach the subtalar joint and reduce the intra-articular calcaneal fractures, provides good clinical outcome and less wound complications compared to the extensile lateral approach. This article introduces the surgical technique and review of the literature regarding the sinus tarsi approach.

• Archives of Plastic Surgery
• /
• 제35권5호
• /
• pp.615-618
• /
• 2008

Purpose: Pyoderma gangrenosum is a rare cutaneous ulcerative disease. First described in 1930, the condition is characterized by progressive ulceration with deeply undermined purple-red edge. The lower extremities are most commonly affected but other parts of the skin and mucous membranes may also be involved. Although medical treatments with topical wound therapy are commonly used, surgical intervention is still controversial. In this paper, we report an atypical case of pyoderma gangrenosum which was characterized by extensive soft tissue breakdown. Methods: A 27-year-old male patient was referred to our institution with a $7{\times}8cm$ sized deeply undermined ulceration with pus-like discharge and fever. Incision and drainage was performed at another clinic 3 days prior to admission to our institution. After a thorough physical examination and the MRI review, a diagnosis of necrotizing faciitis was made. Accordingly, fasciotomy and debridement was performed. However, the wound enlarged progressively and the patient remained highly febrile for 9 days after the treatment. Septic screening did not reveal any occult infection. After a secondary review of the case, the initial diagnosis of necrotizing fasciitis was rejected and changed to pyoderma gangrenosum. With the use of dexamethasone intravenously, the wound improved dramatically and the fever was eliminated. Steroid mediation was tapered with duration of 1 month. The wound was stabilized and subsequently covered with split-thickness skin graft. Results: Split-thickness skin grafting with 1 : 1.5 mesh was successfully taken. Conclusion: Initial clinical features of pyoderma gangrenosum are very similar to that of necrotizing fasciitis. High fever and progressive ulceration with severe pain could invite earlier surgical approach. The advancing wound margins (the well defined violaceous, undermined border and necrotic ulcer base) and lack of isolation of pathogenic organism was used to make the correct diagnosis of pyoderma gangrenosum. We achieved a good result with proper medication and split-thickness skin graft.

• International Journal of Aeronautical and Space Sciences
• /
• 제15권2호
• /
• pp.123-137
• /
• 2014

The aviation gas turbine is composed of many expensive and highly precise parts and operated in high pressure and temperature gas. When breakdown or performance deterioration occurs due to the hostile environment and component degradation, it severely influences the aircraft operation. Recently to minimize this problem the third generation of predictive maintenance known as condition based maintenance has been developed. This method not only monitors the engine condition and diagnoses the engine faults but also gives proper maintenance advice. Therefore it can maximize the availability and minimize the maintenance cost. The advanced gas turbine health monitoring method is classified into model based diagnosis (such as observers, parity equations, parameter estimation and Gas Path Analysis (GPA)) and soft computing diagnosis (such as expert system, fuzzy logic, Neural Networks (NNs) and Genetic Algorithms (GA)). The overview shows an introduction, advantages, and disadvantages of each advanced engine health monitoring method. In addition, some practical gas turbine health monitoring application examples using the GPA methods and the artificial intelligent methods including fuzzy logic, NNs and GA developed by the author are presented.

• 제어로봇시스템학회논문지
• /
• 제20권4호
• /
• pp.408-413
• /
• 2014

In this paper, we propose a fault diagnosis method based on Park's Vector Approach using the Euler's theorem. If we interpreted it as Euler's theorem, it is possible to easily find the phase angle difference between the healthy condition and the fault condition. And, we analyzed the variation of the phase angle and performed the diagnostic method of the induction motor using feature vectors that were obtained by using a Fourier transform. The analysis of time and speed variation of the motor was performed and, as a result, we could find more soft variations than rough variations. In particular, the analysis of the distortion through each phase shows that two-turn and four-turn shorted motors are linearly separable. In this experiment, we know that the maximum breakdown threshold value for determining steady-state fault detection is 49.0788. Simulation and experimental results show the more detectable than conventional method.

• Archives of Reconstructive Microsurgery
• /
• 제11권2호
• /
• pp.153-161
• /
• 2002

Purpose : Plantar surfaces, calcaneal area, and region of Achilles insertion, which are extremely related with weight-bearing area and shoes application, must be reconstructed with glabrous and strong fibrous skin. Numerous methods of reconstructing defects of these regions have been advocated, but the transfer of similar local tissue as a cutaneous flap with preservation of sensory potential would best serve the functional needs of the weight-bearing and non-weight-bearing surfaces of this region. Therefore it is recommended to use the limited skin of medial surface of foot that is similar to plantar region and non-weight-bearing area. In this paper we performed the medial plantar flap transfered as a fasciocutaneous island as one alterative for moderate-sized defects of the plantar forefoot, plantar heel, and area around the ankle in 25 cases and report the result, availability and problem of medial plantar flap. Materials and methods : We performed proximally based medial plantar flap in 22 cases and reverse flow island flap in 3 cases. Average age was $36.5(4{\sim}70)$ years and female was 3 cases. The causes of soft tissue defect were crushing injury on foot 4 cases, small bony exposure at lower leg 1 case, posterior heel defect with exposure of calcaneus 8 cases, severe sore at heel 2 cases, skin necrosis after trauma on posterior foot 4 cases, and defect on insertion area of Achilles tendon 6cases. Average follow up duration was 1.8(7 months-9.5 years) years. Results: Medial plantar flaps was successful in 22 patients. 18 patients preserved cutaneous branches of medial plantar nerve had sensation on transfered flap but diminished sensation or dysesthesia. At the follow up, we found there were no skin ulceration, recurrence of defect or skin breakdown in all 18 patients. But there was one case which occurred skin ulceration postoperatively among another 4 cases not contained medial plantar nerve. At the last follow up, all patients complained diminished sensation and paresthesia at medial plantar area distally to donor site, expecially with 4 patients having severe pain and discomfort during long-time walking. Conclusion : Medial plantar island flap based on medial plantar neurovascualr pedicle have low failure rate with strong fibrous skin and preserve sensibility of flap, so that it is useful method to reconstruct the skin and soft tissue defect of foot. But it should be emphasized that there are some complications such like pain and paresthesia by neuropraxia or injury of medial plantar nerve at more distal area than donor site. We may consider that medial plantar flap have limited flap size and small arc of rotation, and require skin graft closure of the donor defect and must chose this flap deliberately.

• 한국어병학회지
• /
• 제24권3호
• /
• pp.197-204
• /
• 2011

멍게 물렁증 원인규명의 일환으로 2011년 3월에 경남 통영에서 채집된 물렁증 멍게와 건강한 멍게를 대상으로 병리학적 검사를 실시한 결과 물렁증 멍게의 경우 체액량, 비만도 및 피막지수가 현저히 감소하였다. 물렁증 멍게의 피막 imprint 관찰과 배양 시 2개의 편모를 가진 원생동물이 확인되었으며, 물렁증 멍게에 대한 이들 편모충의 감염률은 97.5%인 반면 건강한 멍게에서는 검출되지 않아 본 편모충은 물렁증 멍게에서 특이적으로 검출되는 것으로 조사되었다. 조직학적 검사결과 물렁증 멍게에서 피막섬 유질다발의 붕괴 현상이 관찰되었으며, 편모충으로 추정되는 원생동물들이 다수 관찰되었다. 통영산 물렁증 멍게에서 확인된 편모충은 일본에서 검출된 그것과 매우 유사한 형태적 특징을 갖고 있으며, 향후 공격실험 등 물렁증 유발과 편모충과의 연관성에 대한 추가 연구가 요망된다.