• Korean Journal of Radiology
• /
• 제23권1호
• /
• pp.42-51
• /
• 2022

Objective: This study aimed to investigate the direction of tissue contraction after microwave ablation in ex vivo bovine liver models. Materials and Methods: Ablation procedures were conducted in a total of 90 sites in ex vivo bovine liver models, including the surface (n = 60) and parenchyma (n = 30), to examine the direction of contraction of the tissue in the peripheral and central regions from the microwave antenna. Three commercially available 2.45-GHz microwave systems (Emprint, Neuwave, and Surblate) were used. For surface ablation, the lengths of two overlapped square markers were measured after 2.5- and 5-minutes ablations (n = 10 ablations for each system for each ablation time). For parenchyma ablation, seven predetermined distances between the markers were measured on the cutting plane after 5- and 10-minutes ablations (n = 5 ablations for each system for each ablation time). The contraction in the radial and longitudinal directions and the sphericity index (SI) of the ablation zones were compared between the three systems using analysis of variance. Results: In the surface ablation experiment, the mean longitudinal contraction ratio and SI from a 5-minutes ablation using the Emprint, Neuwave, and Surblate systems were 28.92% and 1.04, 20.10% and 0.53, and 24.90% and 0.45, respectively (p < 0.001). A positive correlation between longitudinal contraction and SI was noted, and a similar radial contraction was observed. In the parenchyma ablation experiment, the mean longitudinal contraction ratio and SI from a 10-minutes ablation using the three pieces of equipment were 38.60% and 1.06, 32.45% and 0.61, and 28.50% and 0.50, respectively (p < 0.001). There was a significant difference in the longitudinal contraction properties, whereas there was no significant difference in the radial contraction properties. Conclusion: The degree of longitudinal contraction showed significant differences depending on the microwave ablation equipment, which may affect the SI of the ablation zone.

• Journal of Chest Surgery
• /
• 제51권5호
• /
• pp.338-343
• /
• 2018

Background: This study examined the role of superficial vein surgery in patients with combined superficial venous reflux and segmental popliteal vein reflux. Methods: We retrospectively reviewed 42 limbs in 38 patients with combined superficial venous reflux and segmental popliteal vein reflux who underwent saphenous vein ablation between January 2014 and February 2017. Patients underwent outpatient follow-up duplex ultrasonography at 3, 6, and 12 months postoperatively. Resolution of deep vein reflux was defined as reversed blood flow in a popliteal segment for less than 1.0 second and a decrease in the reflux time of more than 20% of the preoperative reflux time. Results: The mean follow-up period was 9 months (range, 3-23 months). Saphenous vein ablations were performed by stripping in 24 limbs and radiofrequency ablation in 18 limbs. Preoperative segmental popliteal vein reflux resolved in 21 of the 42 limbs (50%). Conclusion: This study demonstrated that superficial venous surgery corrected segmental popliteal vein reflux in 50% of limbs with combined superficial venous reflux and segmental popliteal vein reflux. Other prospective studies are necessary to elucidate the etiology of the non-reversible cases.

• Journal of electromagnetic engineering and science
• /
• 제9권4호
• /
• pp.188-193
• /
• 2009

A K-band low-power miniaturized planar-type hyperthermia system was developed to replace massive and expensive equipment. The system consists of a VCO with a buffer amplifier, a high-power amplifier module, a 20-dB-coupled line coupler, a chip circulator and two power detectors for signal generation, amplification and power monitoring. All these components have been implemented in planar form on two module blocks. The total size of the hyperthermia system was less than $10\times6.5\times3\;cm^3$. In order to verify the system performance, ablations were carried out on nude mice xenografted with human breast cancer. Ablation results show performance comparable to the massive components-based system. This work shows the feasibility of a low-cost miniaturized hyperthermia system for practical clinical applications.

• 대한치과의사협회지
• /
• 제52권10호
• /
• pp.615-622
• /
• 2014

Oral cancer ablation surgery results in tissue defects with functional loss. Accompanying neck dissection results in facial nerve weakness and dysmorphic changes. To minimize the complications after oral cancer surgery, accurate dissection without damaging facial nerve and vital structures are mandatory. Marginal mandibular branch of facial nerve should be dissected or contained in the superficial layer of deep cervical fascia to minimized facial palsy after operation. Reconstruction after cancer ablations is routine procedures and free flap reconstruction is the most commonly used. Radial forearm free flap is the most versatile flap to reconstruct soft tissue defects and it is easy to design according to the defect size and shape. However, donor site scar and secondary skin graft from thigh result in unesthetic and cumbersome wounds. Double layered collagen graft in the donor site could reduce secondary donor site for skin graft. In conclusion, oral and maxillofacial surgeon should know the exact anatomy of the face and neck during neck dissection. Radial forearm free flap is most versatile flap for soft tissue reconstruction and double collagen graft can reduce postoperative scar and there is no need for secondary skin graft.

• Ocean and Polar Research
• /
• 제31권3호
• /
• pp.257-264
• /
• 2009

Seventeen females of the mud crab Scylla serrata, from the State of Kosrae, Micronesia, were transported to the Fisheries Resources Research Institute, Gyeongsangnam-do, in oxygen-filled plastic bags. After acclimatization to a $30^{\circ}C$ holding temperature, nine females were selected for seed production trials. Spawning was hastened using eyestalk ablations; however, this may not be required in commercialscale mud crab seed production. Primary spawning produced an average of 2.4 million hatched larvae, whereas secondary spawning produced 0.4 million. About 10 days elapsed between spawning and hatching and 30 days between hatching and crablet. Mass mortalities up to 90% were observed between stages zoea 1 and zoea 2 in every trial. The highest survival rate from zoea 1 to crablet was estimated at 0.25%. Most commercial shrimp hatcheries in Korea are equipped with almost all necessary facilities and could be converted easily to mud crab hatcheries, able to run three to four times per year using hatchery technologies developed for blue crabs and Chinese mitten crabs.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
• /
• pp.583-588
• /
• 2005

Indium tin oxide (ITO) is a commonly used conducting transparent oxide film (CTO) used in flat panel display applications. Direct write laser ablation is sometimes employed for ITO patterning and it is important that the substrate material and remaining ITO be affected as little as possible by the laser ablation. In this investigation, femtosecond laser ablation of ITO was studied to identify laser processing parameters which cleanly ablated ITO with a minimum of damage to a glass substrate and surrounding ITO. The Ti:Sapphire chirp pulse amplified femtosecond laser used for the experiments had a wavelength of 775nm and produced pulses with a duration of 150fs at a rate of 2 kHz. Ablation was carried out at a sufficiently high panel scanning speed that single ablation spots could be studied. The pulse energy was adjusted to determine feasible spot diameters and depths which could be ablated into the ITO without damaging the glass substrate. Next, ablation of lines without glass damage was also demonstrated. Experiments were also performed with a high repetition rate (100kHz) femtosecond laser.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
• /
• pp.185-188
• /
• 2007

액체 및 고체추진기관의 내열부품으로 사용하기 위하여 Liquid Silicon Infiltration(액체 실리콘 함침) 공정이 적용된 C/SiC 복합재료를 개발하였다. 탄소섬유 및 탄소직물을 사용하여 필리멘트 와인딩, 테이프 롤링 및 인벌루트 적층 공법이 사용된 다양한 탄소 프리폼이 제작되었다. 내열 부품으로써의 열구조 성능을 극대화시키기 위하여 SiC 함유량, 열처리 조건, 수지 및 기상 함침 조건을 변화시키면서 시편을 제작하고 평가하였다. C/SiC 복합재료를 액체 및 고체추진기관의 내열부품으로 사용하기 위하여 연소시험을 수행하였으며 내열 성능 해석을 위한 수학적 삭마 모델이 개발되었다.

• Korean Journal of Radiology
• /
• 제22권6호
• /
• pp.944-950
• /
• 2021

Objective: To demonstrate the feasibility of percutaneous microwave ablation in desmoid fibromatosis with respect to tumor volume control and improvement in the quality of life. Materials and Methods: Twelve microwave ablations were performed in 9 patients with a histological diagnosis of desmoid fibromatosis between January 2010 and January 2019. The study population included 6 female and 3 male, with an age range of 21-76 years (mean = 46.6 years; standard deviation [SD] = 19.3 years). The mean major axis of the tumors was 10.9 cm (SD = 5.2 cm) and mean lesion volume was 212.7 cm³ (SD = 213 cm³). Their anatomical distribution was as follows: 3 lesions in the thigh, 2 in the gluteus, 2 in the leg and 2 in the periscapular region. We evaluated the reduction in tumor volume and improvement in the quality of life based on the Eastern Cooperative Oncology Group (ECOG) scale. Results: An average tumor volume reduction of 70.4% (SD = 24.9) was achieved, while the quality of life (ECOG scale) improved in 88.9% of patients. Conclusion: Percutaneous microwave ablation may potentially be a safe, effective, and promising technique for controlling tumor volume and improving the quality of life in patients with desmoid fibromatosis.

• The Korean Journal of Pain
• /
• 제29권1호
• /
• pp.3-11
• /
• 2016

A nerve block is an effective tool for diagnostic and therapeutic methods. If a diagnostic nerve block is successful for pain relief and the subsequent therapeutic nerve block is effective for only a limited duration, the next step that should be considered is a nerve ablation or modulation. The nerve ablation causes iatrogenic neural degeneration aiming only for sensory or sympathetic denervation without motor deficits. Nerve ablation produces the interruption of axonal continuity, degeneration of nerve fibers distal to the lesion (Wallerian degeneration), and the eventual death of axotomized neurons. The nerve ablation methods currently available for resection/removal of innervation are performed by either chemical or thermal ablation. Meanwhile, the nerve modulation method for interruption of innervation is performed using an electromagnetic field of pulsed radiofrequency. According to Sunderland's classification, it is first and foremost suggested that current neural ablations produce third degree peripheral nerve injury (PNI) to the myelin, axon, and endoneurium without any disruption of the fascicular arrangement, perineurium, and epineurium. The merit of Sunderland's third degree PNI is to produce a reversible injury. However, its shortcoming is the recurrence of pain and the necessity of repeated ablative procedures. The molecular mechanisms related to axonal regeneration after injury include cross-talk between axons and glial cells, neurotrophic factors, extracellular matrix molecules, and their receptors. It is essential to establish a safe, long-standing denervation method without any complications in future practices based on the mechanisms of nerve degeneration as well as following regeneration.

• 한국추진공학회지
• /
• 제7권3호
• /
• pp.1-7
• /
• 2003

본 연구에서는 열적 삭마에 의한 노즐목 면적 증가량을 알아내기 위해 KSR-III로켓의 주엔진인 KL-3 엔진의 노즐목의 형상을 측정하고자 시도하였으며, 기존에 사용하던 3차원 변위 측정기를 이용한 방식의 접근이 곤란함에 따라 영상처리 기법을 도입한 측정 방식을 고안하여 사용하였다. 영상 기반 노즐목 형상 측정 장치는 만족스런 결과를 보였다. 시험결과 분석을 통해서는 삭마의 형상은 분무 형상에 의해 결정된다는 것과, 삭마의 진행이 3개의 구간으로 나누어 설명할 수 있음을 밝혔는데, 노즐목이 원형을 그대로 유지하며 삭마진행이 미미한 구간, 원형에서 벗어나 요철형상이 발달하면서 삭마진행이 가속되는 구간, 요철형상이 이미 정착되어서 요철의 깊이만 증가하되 삭마량은 미미한 구간이다. 또한 60초 연소 후 노즐목 면적 증가율은 +5.82% 정도로 만족할 만한 수준으로 판단한다.