• Journal of Korean Neurosurgical Society
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• v.30 no.5
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• pp.652-656
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• 2001

Uveal melanoma is uncommon but life-threatening intraocular malignancy and has been treated by irradiation, local excision and enucleation. Gamma-Knife radiosurgery allows a high dose of radiation to be delivered to an intracranial target with a very high spatial accuracy and has been used for the treatment of ocular melanomas. We have treated two cases of uveal melanoma between October 1994 and December 1999. They include one man and one woman(34, 62 years, respectively). They were followed up for 12 momths. Mean maximal dose was 65Gy. In one case, the tumor disappeared 7 months after gamma-knife radiosurgery. In another case, multiple tumors (uveal, suprasellar and cerebellar tumor) had decreased in size. These results show that single and high dose gamma-knife radiosurgery is may be an option in the local control of uveal melanoma which can spare the eyeball and vision.

• Quality Improvement in Health Care
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• v.8 no.1
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• pp.74-83
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• 2001

Background : Since a Gamma Knife had been installed on December 1997, 405 patients have been treated until December 1999 at department of neurosurgery of Seoul National University hospital. The authors analyzed results of a work to improve satisfaction of Gamma Knife surgery patients and to reduce hospital length of stay. Methods : To understand main discontent of patients, a pre-survey was performed from October 1998 to December 1999 using a questionnaire. By Analyzing 93 questionnaire received from 234 patients, pain on frame application, explanation before surgery, waiting time before surgery, waiting time before medical procedure were main discontent factor and overall satisfaction ratio was 71.0%. To improve satisfaction ratio, several quality improvement activity works were designed and applied to 123 patients during the period between January 2000 and September 2000. The same questionnaire were analyzed. Works to reduce the patient hospital LOS were devised and applied during the same period. Results : The overall satisfaction ratio of Gamma Knife radiosurgery patients was increased to 83.7%(P=0.10). The main factor to improve satisfaction ratio was to reduce waiting time(P=0.05) and improvement of discomfort during the surgery(P=0.06). The average LOS was reduced from 3.1 to 2.7 days(P=0.003). Conclusion : As a result of quality assurance activities, the overall satisfaction ratio of patients was improved and LOS was reduced. The pain during frame application was remained as a main discontent factor and a further study is required to reduce this pain.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.58.2-58.2
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• 2010

FPD (Flat Panel Display) 제조 공정에서 사용되는 패턴은 수 ${\mu}m$ 수준까지 감소하였으며, FPD의 크기는 급격하게 대형화 되여 현재 8세대(2200mm*2500mm)에 이르고 있다. 이에 따라, $1\;{\mu}m$ 이상의 크기를 갖는 오염입자에 의한 수율 저하를 극복하기 위한 세정효율의 향상 및 다량의 초순수 사용에 따른 폐수 발생으로 인한 환경오염, 또한 장비의 크기에 따른 공간 효용성 감소와 이에 따른 공정 비용의 증가 등의 어려움에 직면하고 있다. 따라서, 현장에서는 고효율, 저비용의 세정 공정 기술 개발에 대한 연구가 활발히 진행되고 있다. 이러한 문제점들을 해결 하고자 이류체 노즐 세정 장치와, 화학액 린스를 위한 초순수 Spray, 건조 공정에 해당하는 Air-knife, Halogen lamp로 구성된 소형화 된 고속 FPD(Flat Panel Display) 세정기에 대한 연구를 진행 하였다. 이류체 노즐은 초순수와 $N_2$ 가스를 내부에서 혼합하여 액적(Droplet)을 형성하여 고압으로 분사시키는 장치로서 화학액을 사용하지 않고 물리적인 방법으로 오염입자를 제거한다. Spray는 유기 오염입자 제거를 위한 오존수의 린스 공정을 위해 설치 하였다. 세정 후 표면에 남아있는 기판의 액막(water film)은 고압의 가스를 분사하는 Air-knife를 통해 제거하였으며, 고속 공정시 발생할 수 있는 Air-knife에서 제거하지 못한 잔류 액막을 Halogen lamp를 사용하여 효과적으로 제거함으로써, 물반점(water mark) 없는 건조 공정을 얻을 수 있었다. 실험에는 미세 입자의 정량적인 측정을 위하여 유리 기판 대신에 6인치 실리콘 웨이퍼(P-type (100))를 사용하였으며, > $\;1{\mu}m$ 실리카 입자를 스핀방식을 사용하여 정량적으로 균일하게 오염하였으며, 오염물의 개수 및 분포는 파티클 스캐너 (Surfscan 6200, KLA-Tancor, USA)를 사용하여 분포 및 개수를 정량적으로 측정 하였다. 이류체 노즐은 $N_2$ 가스의 압력과 초순수의 압력을 변화시켜 측정하여, 각각 0.20 MPa, 0.01 MPa에서 최적의 세정 결과를 얻을 수 있었으며, 건조 효율은 Air-Knife의 입사 각도와 건조면 간격, 할로겐 램프의 온도를 조절 하여 최적의 조건을 얻을 수 있었다.

• The Journal of Korean Physical Therapy
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• v.25 no.3
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• pp.149-154
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• 2013

Purpose: Spinal instability due to weakness of abdominal muscles is one of the major causes that induces low back pain (LBP). The purpose of this study was to investigate any differences in abdominal muscle activity during curl up, roll out, and jack knife exercises using a swiss-ball or sling. Methods: Twenty healthy subjects were randomly assigned into either a swiss-ball exercise group (SBEG) or a sling exercise group (SEG). Subjects performed curl up, roll out and jack knife exercises using the swiss ball or sling. Activity of abdominal muscles (rectus abdominis and external oblique muscle) was assessed using surface EMG and normalized maximal voluntary isometric contraction (MVIC). The significance of differences between the sling exercise group and the swiss-ball exercise group was evaluated by the independent t-test. Results: These Results indicated that activities of rectus abdominis on right and left of the SEG during the curl up exercise were significantly greater than the SBEG. During the roll out exercise, activity of the abdominal muscle was not significantly different between the SEG and SBEG. In addition, during the jack knife exercise, activities of the right rectus abdominis and left external oblique muscle in the SEG were significantly greater than the SBEG. Conclusion: In conclusion, activity of the abdominal muscles was maximized when curl up and jack knife exercise were performed using the sling rather than the swiss-ball. Therefore, if increased activation of the abdominal muscle is the goal of an exercise program, curl up and jack knife exercises may be useful.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.429-433
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• 2014

As the fabrication technology used in FPDs(flat-panel displays) advances, the size of these panels is increasing and the pattern size is decreasing to the um range. Accordingly, a cleaning process during the FPD fabrication process is becoming more important to prevent yield reductions. The purpose of this study is to develop a FPD cleaning system and a cleaning process using a two-phase flow. The FPD cleaning system consists of two parts, one being a cleaning part which includes a two-phase flow nozzle, and the other being a drying part which includes an air-knife and a halogen lamp. To evaluate the particle removal efficiency by means of two-phase flow cleaning, silica particles $1.5{\mu}m$ in size were contaminated onto a six-inch silicon wafer and a four-inch glass wafer. We conducted cleaning processes under various conditions, i.e., DI water and nitrogen gas at different pressures, using a two-phase-flow nozzle with a gap distance between the nozzle and the substrate. The drying efficiency was also tested using the air-knife with a change in the gap distance between the air-knife and the substrate to remove the DI water which remained on the substrate after the two-phase-flow cleaning process. We obtained high efficiency in terms of particle removal as well as good drying efficiency through the optimized conditions of the two-phase-flow cleaning and air-knife processes.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2334-2338
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• 2020

In recent years, 3D printing technology has received significant research attention. Additionally, 3D printing technology is being applied to study radiation dosimeters of various materials. In this study, a plastic scintillator for 3D printing was developed in a laboratory and used to manufacture a plastic scintillation dosimeter (PSD) with a shape identical to that of the ionization chamber PTW31010. The 16-mm beam of Gamma Knife® Perfexion™ was irradiated to derive the absorbed dose rates of the PSD and PTW31010; they were subsequently compared with the dose rates of the treatment plan. The differences in the dose rates of the Gamma Knife treatment plan and the absorbed dose rates of PTW31010 were within 0.87%. The difference between the dose rates of the Gamma Knife treatment plan and the absorbed dose rates of the PSD were within 4.1%. A linear fit of the absorbed dose rates of four shots involving different dose rates and irradiation angles yielded an adjusted R-square value exceeding 0.9999. A total of 10 repeated measurements were conducted for the same shot to confirm its reproducibility, with a relative error of 0.56%.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.273-280
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• 2001

Objectives : The purpose of this study is to assess the long-term outcome and delayed complications of Gamma Knife radiosurgery for low grade glioma(LGG). Methods : Among 31 patients of LGG who had been treated by using Leksell Gamma Knife between March 1992 and December 1996, we could follow up more than 5 years(range 5-9 years) in 17 patients and evaluated their clinical feature, changes of tumor volume and post-radiosurgical complications. Results : During the mean follow-up period of 7.6 years, the tumor was decreased in 5 patients(29.4%), unchanged in 4(23.5%), increased in 4(23.5%) and recurred in 4(23.5%). The tumor control rate was 52.9%(9/17). We have experienced eighteen postradiosurgical complications in 10 patients(58.8%). Early complication was none and delayed complications included radiation necrosis with cyst in ten cases, bleeding in five, radiation-induced edema in one and malignant transformation in one. Two patients ultimately died as a result of tumor progression during the follow-up period. The mortality rate was 11.7%. Conclusion : Gamma Knife radiosurgery may be useful as an adjunctive therapy for small volume, deep-seated LGG. Although radiosurgery can effectively prevent growth of solid tumor, several delayed complications such as radiation necrosis, cyst formation, bleeding or malignant transformation can develop during the long-term followup period. Because of the possible slow growth rate of LGG and development of the delayed complications, the long-term efficacy of radiosurgery requires further analysis.

• Clinical Endoscopy
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• v.57 no.1
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• pp.36-47
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• 2024

Background/Aims: Scissor-type endoscopic submucosal dissection (ST-ESD) knives can reduce the adverse events associated with ESDs. This study aimed to compare ST-ESD and non-scissor-type (NST)-ESD knives. Methods: We identified ten studies that compared the performance characteristics and safety profiles of ST-ESD and NST-ESD knives. Fixed- and random-effects models were used to calculate the pooled proportions. Heterogeneity was assessed using the I² test. Results: On comparing ST-ESD knives to NST-ESD knives, the weighted odds of en bloc resection was 1.61 (95% confidence interval [CI], 0.90-2.90; p=0.14), R0 resection was 1.10 (95% CI, 0.71-1.71; p=0.73), delayed bleeding was 0.40 (95% CI, 0.17-0.90; p=0.03), perforation was 0.35 (95% CI, 0.18-0.70; p<0.01) and ESD self-completion by non-experts was 1.89 (95% CI, 1.20-2.95; p<0.01). There was no heterogeneity, with an I² score of 0% (95% CI, 0%-54.40%). Conclusions: The findings of reduced odds of perforation, a trend toward reduced delayed bleeding, and an improvement in the rates of en bloc and R0 resection with ST-ESD knives compared to NST-ESD knives support the use of ST-ESD knives when non-experts perform ESDs or as an adjunct tool for challenging ESD procedures.

• Radiation Oncology Journal
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• v.26 no.4
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• pp.263-270
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• 2008

Purpose: This study aimed to quantitatively measure the movement of tumors in real-time and evaluate the treatment accuracy, during the treatment of a liver tumor patient, who underwent radiosurgery with a Synchrony Respiratory motion tracking system of a robot CyberKnife. Materials and Methods: The study subjects included 24 liver tumor patients who underwent CyberKnife treatment, which included 64 times of treatment with the Synchrony Respiratory motion tracking system ($Synchrony^{TM}$). The treatment involved inserting 4 to 6 acupuncture needles into the vicinity of the liver tumor in all the patients using ultrasonography as a guide. A treatment plan was set up using the CT images for treatment planning uses. The position of the acupuncture needle was identified for every treatment time by Digitally Reconstructed Radiography (DRR) prepared at the time of treatment planning and X-ray images photographed in real-time. Subsequent results were stored through a Motion Tracking System (MTS) using the Mtsmain.log treatment file. In this way, movement of the tumor was measured. Besides, the accuracy of radiosurgery using CyberKnife was evaluated by the correlation errors between the real-time positions of the acupuncture needles and the predicted coordinates. Results: The maximum and the average translational movement of the liver tumor were measured 23.5 mm and $13.9{\pm}5.5\;mm$, respectively from the superior to the inferior direction, 3.9 mm and $1.9{\pm}0.9mm$, respectively from left to right, and 8.3 mm and $4.9{\pm}1.9\;mm$, respectively from the anterior to the posterior direction. The maximum and the average rotational movement of the liver tumor were measured to be $3.3^{\circ}$ and $2.6{\pm}1.3^{\circ}$, respectively for X (Left-Right) axis rotation, $4.8^{\circ}$ and $2.3{\pm}1.0^{\circ}$, respectively for Y (Crania-Caudal) axis rotation, $3.9^{\circ}$ and $2.8{\pm}1.1^{\circ}$, respectively for Z (Anterior-Posterior) axis rotation. In addition, the average correlation error, which represents the treatment's accuracy was $1.1{\pm}0.7\;mm$. Conclusion: In this study real-time movement of a liver tumor during the radiosurgery could be verified quantitatively and the accuracy of the radiosurgery with the Synchrony Respiratory motion tracking system of robot could be evaluated. On this basis, the decision of treatment volume in radiosurgery or conventional radiotherapy and useful information on the movement of liver tumor are supposed to be provided.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.146-150
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• 2004

We researched carbon nanotube(CNT) cartridge as a CNT sample for the fabrication of nanotweezer which is composed of a couple of single CNT tip. Our CNT cartridge was made by dielectrophoretic methods, a kind of micromanipulation technique using electric field. Therein we intended to fabricate the CNT cartridge with just conventional function generators and a set of simple electrode. A knife edge and a flat metal electrode were employed as a couple of electrode, and these electrode pair faced each other with the gap. When the gap is filled with CNT suspension, we induced AC electric field into the gap. Then CNTs was attached on the sharp edge in knife edge by dielectrophoresis. This knife edge with attached CNTs is called as the CNT cartridge.