• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.771-779
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• 2021

It is necessary to overlap several peaks to form spread out Bragg peak (SOBP) in order to cover the tumor volume because a mono-energetic proton beam forms a narrow Bragg peak. The tumor density has been considered as a brain tissue and then the absorbed dose of the tumor is calculated using Monte Carlo simulations. However, densities of tumors were not a constant. In this study, the SOBP of proton beams was calculated according to changing density of tumors by using Geant4. Tumors were selected as 10 mm and 20 mm width which were the treatment range in the brain phantom. The energies and relative weights of the proton beams were calculated using mathematical formula to form the SOBP suitable for the location and size of the tumor. As the density of the tumor was increased, the 95% modulation range and the practical range were decreased, and average absorbed dose in the 95% modulation range was increased. The change of the tumor density affects the dose distribution of the proton beams, which results in short SOBP within the tumor volume. The consideration of the tumor density affects the determination of the range, so that the margin of the treatment volume can be minimized, and the advantages of proton therapy can be maximized.

• Radiation Oncology Journal
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• v.15 no.4
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• pp.339-348
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• 1997

Purpose : To evaluate the role of postoperative radiation therapy after curative resection of sigmoid colon cancer Materials and Methods : From 1988 to 1993, a total of 93 Patients with curative resectable sigmoid colon cancer of modified Astler-Coiler (MAC) stage B2, B3, C2, C3 was divided into two groups on the basis of those who received radiation treatment and those who did not. Forty-three patients who treated by surgery alone were classified as postop RT (-) group The remaining 50 patients who underwent postoperative radiotherapy were classified as postop RT (+) group. In all patients in Postop RT (+) group. radiation therapy was delivered using 4 or 10 MV linear accelerators to treat the tumor bed with approximately 5cm margin to a total dose 50.4-61Gy(median 54Gy) in 1.8Gy per fraction. Thirty-two patients were treated. with 5-Fluorouracil based adjuvant chemotherapy at least 3 cycles. but these was no significant difference between two groups. Treatment failure Pattern, 5-year local failure-free survival rates (LFFS), and 5-year disease-free survival rates (DFS) were compared between two groups. Result : Five year LFFS and DFS were $85.1\%,\;68.5\%$, respectively, In Postop RT (-) group, LFFS was $76.2\%$ compared with $91.7\%$ in Postop RT (+) group. Improved LFFS and DFS were seen for patients with stage C3 sigmoid colon carcinoma with postoperative radiation therapy compared with postop RT (-) group (P=0.01, p=0.06 respectively), in stage B3, LFFS washigher in postop RT (+) group than that in Postop RT (-) group. although itwas not significant. Especially, local control was higher in stage 74 inpostop RT (+) group than that in postop RT (-) group, Conclusion : This studv showed significantly improved LFFS and DFS in MAC Stage C3 and improved tendency of LFFS and DFS in MAC Stage B3 disease. Large scale prospective study is required to verify the role of adjuvant radiation therapy in resectable sigmoid colon cancer.

• Radiation Oncology Journal
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• v.27 no.1
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• pp.23-28
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• 2009

Purpose: This study was designed to evaluate the effectiveness of postoperative radiotherapy for patients with low-grade astrocytomas and to define an optimal radiotherapeutic regimen and prognostic factors. Materials and Methods: A total of 69 patients with low-grade astrocytomas underwent surgery and postoperative radiotherapy immediately following surgery at our institution between October 1989 and September 2006. The median patient age was 36 years. Forty-one patients were 40 years or younger and 28 patients were 41 years or older. Fourteen patients underwent a biopsy alone and the remaining 55 patients underwent a subtotal resection. Thirty-nine patients had a Karnofsky performance status of less than 80% and 30 patients had a Karnofsky performance status greater than 80%. Two patients were treated with whole brain irradiation followed by a coned down boost field to the localized area. The remaining 67 patients were treated with a localized field with an appropriate margin. Most of the patients received a dose of $50\sim55$ Gy and majority of the patients were treated with a dose of 54 Gy. Results: The overall 5-year and 7-year survival rates for all of the 69 patients were 49% and 44%, respectively. Corresponding disease free survival rates were 45% and 40%, respectively. Patients who underwent a subtotal resection showed better survival than patients who underwent a biopsy alone. The overall 5-year survival rates for patients who underwent a subtotal resection and patients who underwent a biopsy alone were 57% and 38%, respectively (p<0.05). Forty-one patients who were 40 years or younger showed a better overall 5-year survival rate as compared with 28 patients who were 41 years or older (56% versus 40%, p<0.05). The overall 5-year survival rates for 30 patients with a Karnofsky performance status greater than 80% and 39 patients with a Karnofsky performance status less than 80% were 51% and 47%, respectively. This finding was not statistically significant. Although one patient was not able to complete the treatment because of neurological deterioration, there were no significant treatment related toxicities. Conclusion: Postoperative radiotherapy following surgery is a safe and effective treatment for patients with low-grade astrocytomas. The extent of surgery and age were noted as significant prognostic factors in this study. However, further effective treatment might be necessary in the future to improve long-term survival rates.

• Radiation Oncology Journal
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• v.23 no.2
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• pp.85-91
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• 2005

Purpose : This study was conducted to analyze treatment outcome and prognostic significance of World Health Organization (WHO)-defined thymic epithelial tumor (TET) subtype and to assess optimal radiation target volume in patients receiving surgery and adjuvant radiation therapy with TET. Materials and Methods: The record of 160 patients with TET, who received surgical resection at the Samsung medical Center, from December 1994 to June 2004, were reviewed. 99 patients were treated with postoperative radiation therapy (PORT). PORT was recommended when patients had more than one findings among suspicious Incomplete resection or positive resection margin or Wasaoka stage $II\~IV$ or WHO type $B2\~C$. PORT peformed to primary tumor bed only with a mean dose of 54 Gy. The prognostic factor and pattern of failure were analyzed retrospectively. Results : The overall survival rate at 5 years was $87.3\%$. Age (more than 60 years $77.8\%$, less than 60 years $91.1\%$; p=0.03), Wasaoka stage (I $92.2\%$, II $95.4\%$, III $82.1\%$, IV $57.5\%$; p=0.001), WHO tumor type (A-Bl $96.0\%$, B2-C $82.3\%$; p=0.001), Extent of resection (R0 resection $92.3\%$, R1 or 2 resection $72.6\%$, p=0.001) were the prognostic factors according to univariate analysis. But WHO tumor type was the only significant prognostic factor according to multivariate analysis. Recurrence was observed in 5 patients of 71 Masoka stage I-III patients who received grossly complete tumor removal (R0, R1 resection) and PORT to primary tumor bed. Mediastinal recurrence was observed In only one patients. There were no recurrence within irradiation field. Conclusion : WHO tumor type was the important prognostic factor to predict survival of patients with TET. This study suggest that PORT to only primary tumor bed was optimal. To avoid pleura- or pericardium-based recurrence, further study of effective chemotherapy should be investigated.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.73-80
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• 2014

The objective of this paper is to assess the service life and retrain methods of specimens, which were subjected to carbonation attack, obtained from mix proportion of Sam-cheok LNG storage tank under construction. As the results, accelerated-carbonation penetration depths of 7, 28, 56 ages indicated 4.45, 9.19, 13.37mm, and even considering for cover depths of steel of LNG storage tank under real operation, it was enough. In addition, with carbonation velocity coefficient calculated by carbonation penetration depths, the service life to design cover depth(70, 80, 90, 100mm) of PC outer tank of LNG storage tank was 779, 1017, 1287, 1589 years and 466, 609, 771, 951 years, respectively, considering the $CO_2$ concentration in air which account for the 0.03% and 0.05%. Also, the restrain methods to carbonation attack were feasible through controlling the factors affecting the changes of hydration products such as $Ca(OH)_2$, ion composition in pore solution and matter mobility of organization structures within hardened concrete.

• Journal of the military operations research society of Korea
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• v.34 no.2
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• pp.163-174
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• 2008

The military is an organization where reliability and availability take much more importance than in any other organization. And, in line with a recent trend of putting emphasis on 'system readiness', not only functions but also availability of a weapon system has become one of achievement targets. In this regard, the military keeps spares for important facility and equipment, which is called as Maintenance Float (M/F), in order to enhance reliability and availability in case of an unforeseen event. The military has calculated yearly M/F requirements based on the number of equipment and utilization rate. However, this method of calculation has failed to meet the intended targets of reliability and availability due to lack of consideration on the characteristics of equipment malfunctions and maintenance unit's capability. In this research, we present an analysis model that can be used to determine an optimal M/F inventory level based on queuing and absorbed Markov chain theories. And, we applied the new analysis model to come out with an optimal volume of K-1 tank M/F for the OO division, which serves as counterattack military unit. In our view, this research is valuable because, while using more tractable methodology compared to previous research, we present a new analysis model that can describe decision making process on M/F level more satisfactorily.

• Korean Security Journal
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• no.54
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• pp.149-179
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• 2018

October 31, 2017, a man named Saipov who follows ISIS killed 8 people and injured nearly 20 others by driving his truck to the riverside bicycle path in Manhattan, New York, in an act of terror. June 5, 2017, the Islamic extremist Yacqub Khayre held a woman hostage in a suburb of Melbourne, Australia, before being killed by the police. Various countries around the world including the UK, France, and Germany are in war against terrorism. The terrorists change their target from hard targets such as government officials to vulnerable soft target, intensifying the public's fear, and, unlike in the past when they were organized by governments or organizations, extremists such as ISIS followers are now acting on their own in the act of terrorism. Also, as they use vehicles, pressure cooker, and other objects that can be easily found for terrorism, it is becoming more difficult for the police to prepare against terrorist attacks. Meanwhile, some terrorism researchers argue that conversational techniques (negotiation) used by the police are now of no use, as shown in the cases like 9/11 attacks in 2001 and 2016 Nice attack in France in which the suspects committed terrorist attacks without leaving enough time for the police to take action and that, therefore, tactical suppression techniques need to be developed. Therefore, this study suggested police negotiation techniques are necessary not only for terrorist attacks but also for overall police work, including handling intoxicated people at police station, and proposed ways to activate conversational techniques for police organizations.

• Korean Journal of Construction Engineering and Management
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• v.9 no.5
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• pp.159-167
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• 2008

This study provides a effective approach to the construction management problem with the limited number or amount of available resources using the analytic hierarchy process. Construction management is a series of decision making processes for planning and controling of cost, time and quality as main objectives in construction works. When several activities need the limited same resource at the same time, it is very hard to decide the priority of the activities in the real situations. For that the scientific decision making method and procedure for resource allocation are required. This study solves the resource allocation problem by dealing with the decision making problem which the activities are distributed to multiple projects and under multiple criteria. The analytic hierarchy process is a method devised to solve complex multi-criteria decision problems. The result shows that this study can be effectively used to make decisions in situations involving multiple objectives by evaluating the prioritized ranking and degree of the activity alternatives based on the overall preferences.

• Radiation Oncology Journal
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• v.28 no.2
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• pp.99-105
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• 2010

Purpose: To compare radiation dose of the brain and lens among various conventional whole brain radiotherapy (WBRT) techniques. Materials and Methods: Treatment plans for WBRT were generated with planning computed tomography scans of 11 patients. A traditional plan with an isocenter located at the field center and a parallel anterior margin at the lateral bony canthus was generated (P1). Blocks were automatically generated with a 1 cm margin on the brain (5 mm for the lens). Subsequently, the isocenter was moved to the lateral bony canthus (P2), and the blocks were replaced into the multileaf collimator (MLC) with a 5 mm leaf width in the craniocaudal direction (P3). For each patient plan, 30 Gy was prescribed at the isocenter of P1. Dose volume histogram (DVH) parameters of the brain and lens were compared by way of a paired t-test. Results: Mean values of $D_{max}$ and $V_{105}$ of the brain in P1 were 111.9% and 23.6%, respectively. In P2 and P3, $D_{max}$ and $V_{105}$ of the brain were significantly reduced to 107.2% and 4.5~4.6%, respectively (p<0.001). The mean value of $D_{mean}$ of the lens was 3.1 Gy in P1 and 2.4~2.9 Gy in P2 and P3 (p<0.001). Conclusion: WBRT treatment plans with an isocenter located at the lateral bony canthus have dosimetric advantages for both the brain and lens without any complex method changes.

• Radiation Oncology Journal
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• v.28 no.3
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• pp.177-183
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• 2010

Purpose: Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Materials and Methods: Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inframammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. Results: The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. Conclusion: The use of 3D CT based planning reduced the radiation field in early breast cancer patients with small breasts in relation to conventional planning. Though a coherent definition of the breast is needed, CT-based planning generated the better plan in terms of reducing the irradiation volume of normal tissue. Moreover it was possible that 3D CT based planning showed better CTV coverage including postoperative change.