• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.3
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• pp.93-104
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• 2018

This study is about occurrence pattern of vacant spaces as a urban decline indicator to consider a decline of old hillside residential area from spatial structure perspective. For investigation based upon vacant space and the street structure, this study selects Ami Chojang-dong in Seo-gu, Busan, of which 79.7% of total area is over a gradient of $10^{\circ}$. Focused on relationship between occurrence pattern of vacant spaces and 'vertical alleys(link)' serving as main movement path of local residents in hillside residential area, the length, numbers, slopes, and use characteristic of vertical alleys were analyzed using Arc GIS 9.3 program to classify characteristic zone types of spacial structure in hillside residential area. After the occurrence pattern of vacant space are interpreted in relation with building density, vertical alleys' number length slope, the social and economic issues have been considered as well. After analyzing the occurrence pattern of vacant space, this study argues that the occurrence pattern of vacant space in old hillside residential area is rather affected by street structure system consisting of vertical alleys than the impacts of social economical issues.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.9-14
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• 2021

This study examined dose change depending on the reposition error of the junction at the time of treatment with multi-isocenter volumetric modulated arc therapy. This study selected a random treatment region in the Arccheck Phantom and established the treatment plan for multi-isocenter volumetric modulated arc therapy. Then, after setting the error of the junction at 0 ~ 4 mm in the X (left), Y (upper), and Z (inner and outer) directions, the area was irradiated using a linear accelerator; the point doses and gamma indexes obtained through the Phantom were subsequently analyzed. It was found that when errors of 2 and 4 mm took place in the X and Y directions, the gamma pass rates (point doses) were 99.3% (2.085) and 98% (2.079 Gy) in the former direction and 98.5% (2.088) and 95.5% (2.093 Gy) in the latter direction, respectively. In addition, when errors of 1, 2, and 4 mm occurred in the inner and outer parts of the Z direction, the gamma pass rates (point doses) were found to be 94.8% (2.131), 82.6% (2.164), and 72.8% (2.22 Gy) in the former part and 93.4% (2.069), 90.6% (2.047), and 79.7% (1.962 Gy) in the latter part, respectively. In the X and Y directions, errors up to 4 mm were tolerable; however, in the Z direction, error values exceeding 1 mm were beyond the tolerance level. This suggests that for high and low dose areas, errors in the direction same as the progress direction in the treatment region have a more sensitive dose distribution. If the guidelines for set-up errors are established at the institutional level through continuous research in the future, it will be possible to provide good quality treatment using junctions.

• Korean Journal of Materials Research
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• v.7 no.2
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• pp.102-106
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• 1997

Micro gas sensors including thin film catal) tic type require stress-free memhrancs for etch stop of Si anisotropic etching and sublayer of sensing elements hecause stress is one of the main factors affecting breakdown of thin membranes. This paper reports the effects of deposition conditions on stress and refractive index of $SiN_{x}/SiO_{x}/(NON)$ films deposited by low pressure c11ernic;rl vapor deposition(L, t'CVI)) 2nd reactve sputtering. In the case of I.PCVI1, the stresses of $SiN_{x}$ and NON films arc $7.6{\times}10^{8}dyne/cm^2$ and $3.3{\times}10^{8}dyne/cm^2$, respectibely, and the refractive indices are 3.05 and 152, respectively. In the cxse oi the sputtered SiN, , compressi\e stress decreased in magnitude and then turned to tensility as increasing proc, ess pressure by lmtorr to 30mtorr and cicreasmg applied power density by $2.74W/cm^2$ to $1.10W/cm^2$. The hest value of film stress obt;~ined under condition of lOmtorr and $1.37W/cm^2$ in this' experiment was $1.2{\times}10^{9}dyne/cm^2$ cnnipressive. The refr~ict~ve index decreased from 2 05 to 1 89 as decreasing applied power density by lnitorr to 3Orntorr and increasing process pressure hy $2.74W/cm^2$ to $1.10W/cm^2$. Stresses of films deposited by both LPCVL) and sputtering decreased as incre;lsing temperature and showed plastic behavior as decreasing temperature.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.87-99
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• 2016

Purpose : This study will evaluate the clinical utility by applying clinical schematic that uses monoenergy or dual energy as according to the location of tumors to the stereotactic radiotherapy to compare the change in actual dose given to the real tumor and the dose that locates adjacent to the tumor. Materials and Methods : CT images from a total of 10 patients were obtained and the clinical planning were planned based on the volumetric modulated arc therapy on monoenergy and dual energy. To analyze the change factor in the tumor, Comformity Index(CI) and Homogeneity Index(HI) and maximum dose quantity were each calculated and comparing the dose distribution on normal tissues, $V_{10}$ and $V_5$, first ~ fourth ribs closest to the tumor ($1^{st}{\sim}4^{th}$ Rib), Spinal Cord, Esophagus and Trachea were selected. Also, in order to confirm the accuracy on which the planned dose distribution is really measured, the 2-dimensional ion chamber array was used to measure the dose distribution. Results : As of the tumor factor, CI and HI showed a number close to 1 when the two energies were used. As of the maximum dose, the front chest wall showed 2% and the dorsal tumor showed equivalent value. As of normal tissue, the front chest wall tumors were reduced by 4%, 5% when both energies were used in the adjacent rib and as of trachea, reduced by 11%, 17%. As of the dose in the lung, as of $V_{10}$, it reduced by 1.5%, $V_5$ by 1%. As of the rear chest wall, when both energies were used, the ribs adjacent to the tumors showed 6%, 1%, 4%, 12% reduction, and in the lung dose distribution, $V_{10}$ reduced by 3%, and $V_5$ reduced by 3.1%. The dose measurement in all energies were in accordance to the results of Gamma Index 3mm/3%. Conclusion : It is considered that rather than using monoenergy, utilizing double energy in the clinical setting can be more effectively applied to the superficial tumors.

• The Journal of Engineering Geology
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• v.23 no.1
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• pp.57-65
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• 2013

We developed a computer program (CDFlow v. 1.0) to design countermeasures against debris flows in natural terrain. The program can predict the probability of landslides occurring in natural terrain and can estimate the zone of damage caused by a debris flow. It can also be used to design the location and size of countermeasures against the debris flow. The program is run using the ArcGIS Engine, which is one of the most well-known Geographic Information System (GIS) tools for developers. The quasi-dynamic wetness index and the infinite slope stability equation were applied to predict landslide probability as a type of slope safety factor. The calculated safety factor was compared with the required safety factor, and areas of high probable potential for landslides were then selected and represented on the digital map. The volume of debris flow was estimated using these areas of high probable potential for landslides and soil depth. The accumulated volume of debris flow can be calculated along the flow channel. To assess the accuracy of the program, it was applied to a real landslide site at Deoksan-ri, Inje-gun, Kangwon-Province, where four debris barriers have been installed in the watershed of the site. The results of soil tests and a field survey indicate that the program has great potential for estimating probable landslide areas and the trajectory of debris flows. Calculation of the capacity volume of existing debris barriers revealed that they had insufficient capacity to store the calculated amount of debris flow. Therefore, this program enables a rational estimation of the optimal location and size of debris barriers.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.4
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• pp.549-563
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• 2008

The purpose of this research is to identify the urban structure in Korea. Though there is research regarding urbanization, there is little regarding the urban structure of the Korean economy. In this paper, two issues will be discussed: the measurements of inter-city and intra-city structure in Korean Metropolitan Statistical Areas (MSAs), which is newly defined. First, the city size rank rule, widely known as Zipf’s Law, will illustrate Korean the inter-city structure. The city size rank rule gives an idea whether Korean MSAs are balanced or not. In general, Korea has a heavy concentration in the Seoul MSA in terms of population. It could be either that the Seoul MSA is too big or that the Busan MSA is too small or both. If this is the primacy problem, a decentralization policy is necessary. On the other hand, if it is a second city problem, development policies for the Busan MSA and Daegu MSA are more important. Next, the Korean intra-city structure will be discussed. The evolutions of the MSAs explain intra-city structure by analyzing population density function and the housing price function. Some large MSAs such as Seoul and Busan have experienced urban sprawl, while other MSAs have experienced urban concentration. The population density gradient by the distance from the ARC GIS shows the growth rate of a city. According to the Spatial Mismatch Index between population and employment, the Ulsan MSA, Gwangju MSA, and Suwon-Hwaseong-Osan MSA are more mismatched, while the Daejeon MSA and Incheon MSA are less mismatched. Therefore, these analyses of Korean urban structure are meaningful in developing regional policy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.73-79
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• 2013

Crystalline silicon solar cells with $SiN_x/SiN_x$ and $SiN_x/SiO_x$ double layer anti-reflection coatings(ARC) were studied in this paper. Optimizing passivation effect and optical properties of $SiN_x$ and $SiO_x$ layer deposited by PECVD was performed prior to double layer application. When the refractive index (n) of silicon nitride was varied in range of 1.9~2.3, silicon wafer deposited with silicon nitride layer of 80 nm thickness and n= 2.2 showed the effective lifetime of $1,370{\mu}m$. Silicon nitride with n= 1.9 had the smallest extinction coefficient among these conditions. Silicon oxide layer with 110 nm thickness and n= 1.46 showed the extinction coefficient spectrum near to zero in the 300~1,100 nm region, similar to silicon nitride with n= 1.9. Thus silicon nitride with n= 1.9 and silicon oxide with n= 1.46 would be proper as the upper ARC layer with low extinction coefficient, and silicon nitride with n=2.2 as the lower layer with good passivation effect. As a result, the double layer AR coated silicon wafer showed lower surface reflection and so more light absorption, compared with $SiN_x$ single layer. With the completed solar cell with $SiN_x/SiN_x$ of n= 2.2/1.9 and $SiN_x/SiO_x$ of n= 2.2/1.46, the electrical characteristics was improved as ${\Delta}V_{oc}$= 3.7 mV, ${\Delta}_{sc}=0.11mA/cm^2$ and ${\Delta}V_{oc}$=5.2 mV, ${\Delta}J_{sc}=0.23mA/cm^2$, respectively. It led to the efficiency improvement as 0.1% and 0.23%.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.543-550
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• 2009

The single-crystal structure of largely ammonium-exchanged zeolite Y dehydrated at room temperature (293 K) and 1 ${\times}\;10^{-6}$ Torr. has been determined using synchrotron X-radiation in the cubic space group $Fd\overline{3}m\;(a=24.9639(2)\AA)$ at 294 K. The structure was refined to the final error index $R_1$ = 0.0429 with 926 reflections where $F_o>4\sigma(F_o)$; the composition (best integers) was identified as |$(NH_4)_{60}Na_{11}$|[$Si_{121}Al_{71}O_{384}$]-FAU. The 11 $Na^{+}$ ions per unit cell were found at three different crystallographic sites and 60 ${NH_4}^{+}$ ions were distributed over three sites. The 3 $Na^{+}$ ions were located at site I, the center of the hexagonal prism ($Na-O\;=\;2.842(5)\;\AA\;and\;O-Na-O\;=\;85.98(12)^{\circ}$). The 4 $Na^{+}$ and 22 ${NH_4}^{+}$ ions were found at site I' in the sodalite cavity opposite the double 6-rings, respectively ($Na-O\;=\;2.53(13)\;\AA,\;O-Na-O\;=\;99.9(7)^{\circ},\;N-O\;=\;2.762(11)\;\AA,\;and\;O-N-O =\;89.1(5)^{\circ}$). About 4 $Na^{+}$ ions occupied site II ($(Na-O\;=\;2.40(4)\;\AA\;and\;O-Na-O\;=\;108.9(3)^{\circ}$) and 29 ${NH_4}^{+}$ ions occupy site II ($N-O\;=\;2.824(9)\;\AA\;and\;O-N-O\;=\;87.3(3)^{\circ}$) opposite to the single 6-rings in the supercage. The remaining 9 ${NH_4}^{+}$ ions were distributed over site III' ($N-O\;=\;2.55(3),\;2.725(13)\;\AA\;and\;O-N-O\;=\;94.1(13),\;62.16(15),\;155.7(14)^{\circ}$).

• Journal of Digital Convergence
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• v.20 no.4
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• pp.469-482
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• 2022

The purpose of this study is to analyze regional variation factors of hypertension treatment rate in COVID-19 based on the analysis results based on ecological methodology. To this end, data suitable for ecological analysis were collected from the Korea Centers for Disease Control and Prevention's regional health statistics, local government COVID-19 confirmed cases, National Health Insurance Corporation, Health Insurance Review and Assessment Service's welfare statistics, and Korea Transport Institute's traffic access index. Descriptive statistics and correlation analysis were conducted using SPSS Statistics 23 for regional variation and related factors in hypertension treatment rate, and geographical weighted regression analysis was conducted using Arc GIS for regional variation factors. As a result of the study, the overall explanatory power of the calculated geo-weighted regression model was 27.6%, distributed from 23.1% to 33.4% by region. As factors affecting the treatment rate of hypertension, the higher the rate of basic living security medical benefits, diabetes treatment rate, and health institutions per 100,000 population, the higher the rate of hypertension treatment, the lower the number of COVID-19 confirmed patients, the lower the rate of physical activity, and the alcohol consumption. Percentage of alcohol consumption decreased due to COVID-19 pandemic. It was analyzed that the lower the ratio, the higher the treatment rate for hypertension. Based on these results, the analysis of regional variables in the treatment rate of hypertension in COVID-19 can be expected to be effective in managing the treatment rate of hypertension, and furthermore, it is expected to be used to establish community-centered health promotion policies.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.2
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• pp.145-156
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• 2015

Purpose : The purpose of this study is to evaluate the efficiency of Split VMAT planning(Contouring rectum divided into an upper and a lower for reduce rectum dose) compare to Conventional VMAT planning(Contouring whole rectum) for prostate cancer radiotherapy involving pelvic lymph nodes. Materials and Methods : A total of 9 cases were enrolled. Each case received radiotherapy with Split VMAT planning to the prostate involving pelvic lymph nodes. Treatment was delivered using TrueBeam STX(Varian Medical Systems, USA) and planned on Eclipse(Ver. 10.0.42, Varian, USA), PRO3(Progressive Resolution Optimizer 10.0.28), AAA(Anisotropic Analytic Algorithm Ver. 10.0.28). Lower rectum contour was defined as starting 1cm superior and ending 1cm inferior to the prostate PTV, upper rectum is a part, except lower rectum from the whole rectum. Split VMAT plan parameters consisted of 10MV coplanar $360^{\circ}$ arcs. Each arc had $30^{\circ}$ and $30^{\circ}$ collimator angle, respectively. An SIB(Simultaneous Integrated Boost) treatment prescription was employed delivering 50.4Gy to pelvic lymph nodes and 63~70Gy to the prostate in 28 fractions. $D_{mean}$ of whole rectum on Split VMAT plan was applied for DVC(Dose Volume Constraint) of the whole rectum for Conventional VMAT plan. In addition, all parameters were set to be the same of existing treatment plans. To minimize the dose difference that shows up randomly on optimizing, all plans were optimized and calculated twice respectively using a 0.2cm grid. All plans were normalized to the prostate $PTV_{100%}$ = 90% or 95%. A comparison of $D_{mean}$ of whole rectum, upperr ectum, lower rectum, and bladder, $V_{50%}$ of upper rectum, total MU and H.I.(Homogeneity Index) and C.I.(Conformity Index) of the PTV was used for technique evaluation. All Split VMAT plans were verified by gamma test with portal dosimetry using EPID. Results : Using DVH analysis, a difference between the Conventional and the Split VMAT plans was demonstrated. The Split VMAT plan demonstrated better in the $D_{mean}$ of whole rectum, Up to 134.4 cGy, at least 43.5 cGy, the average difference was 75.6 cGy and in the $D_{mean}$ of upper rectum, Up to 1113.5 cGy, at least 87.2 cGy, the average difference was 550.5 cGy and in the $D_{mean}$ of lower rectum, Up to 100.5 cGy, at least -34.6 cGy, the average difference was 34.3 cGy and in the $D_{mean}$ of bladder, Up to 271 cGy, at least -55.5 cGy, the average difference was 117.8 cGy and in $V_{50%}$ of upper rectum, Up to 63.4%, at least 3.2%, the average difference was 23.2%. There was no significant difference on H.I., and C.I. of the PTV among two plans. The Split VMAT plan is average 77 MU more than another. All IMRT verification gamma test results for the Split VMAT plan passed over 90.0% at 2 mm / 2%. Conclusion : As a result, the Split VMAT plan appeared to be more favorable in most cases than the Conventional VMAT plan for prostate cancer radiotherapy involving pelvic lymph nodes. By using the split VMAT planning technique it was possible to reduce the upper rectum dose, thus reducing whole rectal dose when compared to conventional VMAT planning. Also using the split VMAT planning technique increase the treatment efficiency.