• Journal of Environmental Impact Assessment
• /
• v.30 no.5
• /
• pp.271-296
• /
• 2021

Since the thermal stratification in a reservoir inhibits the vertical mixing of the upper and lower layers and causes the formation of a hypoxia layer and the enhancement of nutrients release from the sediment, changes in the stratification structure of the reservoir according to future climate change are very important in terms of water quality and aquatic ecology management. This study was aimed to develop a data-driven inflow water temperature prediction model for Daecheong Reservoir (DR), and to predict future inflow water temperature and the stratification structure of DR considering future climate scenarios of Representative Concentration Pathways (RCP). The random forest (RF)regression model (NSE 0.97, RMSE 1.86℃, MAPE 9.45%) developed to predict the inflow temperature of DR adequately reproduced the statistics and variability of the observed water temperature. Future meteorological data for each RCP scenario predicted by the regional climate model (HadGEM3-RA) was input into RF model to predict the inflow water temperature, and a three-dimensional hydrodynamic model (AEM3D) was used to predict the change in the future (2018~2037, 2038~2057, 2058~2077, 2078~2097) stratification structure of DR due to climate change. As a result, the rates of increase in air temperature and inflow water temperature was 0.14~0.48℃/10year and 0.21~0.41℃/10year,respectively. As a result of seasonal analysis, in all scenarios except spring and winter in the RCP 2.6, the increase in inflow water temperature was statistically significant, and the increase rate was higher as the carbon reduction effort was weaker. The increase rate of the surface water temperature of the reservoir was in the range of 0.04~0.38℃/10year, and the stratification period was gradually increased in all scenarios. In particular, when the RCP 8.5 scenario is applied, the number of stratification days is expected to increase by about 24 days. These results were consistent with the results of previous studies that climate change strengthens the stratification intensity of lakes and reservoirs and prolonged the stratification period, and suggested that prolonged water temperature stratification could cause changes in the aquatic ecosystem, such as spatial expansion of the low-oxygen layer, an increase in sediment nutrient release, and changed in the dominant species of algae in the water body.

• Progress in Medical Physics
• /
• v.27 no.2
• /
• pp.64-71
• /
• 2016

We develop a manufacture procedure for the production of a patient specific customized bolus (PSCB) using a 3D printer (3DP). The dosimetric accuracy of the 3D-PSCB is evaluated for electron beam therapy. In order to cover the required planning target volume (PTV), we select the proper electron beam energy and the field size through initial dose calculation using a treatment planning system. The PSCB is delineated based on the initial dose distribution. The dose calculation is repeated after applying the PSCB. We iteratively fine-tune the PSCB shape until the plan quality is sufficient to meet the required clinical criteria. Then the contour data of the PSCB is transferred to an in-house conversion software through the DICOMRT protocol. This contour data is converted into the 3DP data format, STereoLithography data format and then printed using a 3DP. Two virtual patients, having concave and convex shapes, were generated with a virtual PTV and an organ at risk (OAR). Then, two corresponding electron treatment plans with and without a PSCB were generated to evaluate the dosimetric effect of the PSCB. The dosimetric characteristics and dose volume histograms for the PTV and OAR are compared in both plans. Film dosimetry is performed to verify the dosimetric accuracy of the 3D-PSCB. The calculated planar dose distribution is compared to that measured using film dosimetry taken from the beam central axis. We compare the percent depth dose curve and gamma analysis (the dose difference is 3%, and the distance to agreement is 3 mm) results. No significant difference in the PTV dose is observed in the plan with the PSCB compared to that without the PSCB. The maximum, minimum, and mean doses of the OAR in the plan with the PSCB were significantly reduced by 9.7%, 36.6%, and 28.3%, respectively, compared to those in the plan without the PSCB. By applying the PSCB, the OAR volumes receiving 90% and 80% of the prescribed dose were reduced from $14.40cm^3$ to $0.1cm^3$ and from $42.6cm^3$ to $3.7cm^3$, respectively, in comparison to that without using the PSCB. The gamma pass rates of the concave and convex plans were 95% and 98%, respectively. A new procedure of the fabrication of a PSCB is developed using a 3DP. We confirm the usefulness and dosimetric accuracy of the 3D-PSCB for the clinical use. Thus, rapidly advancing 3DP technology is able to ease and expand clinical implementation of the PSCB.

• Journal of Radiation Protection and Research
• /
• v.32 no.3
• /
• pp.105-110
• /
• 2007

Purpose : In spite of recent remarkable improvement of diagnostic imaging modalities such as CT, MRI, and PET and radiation therapy planing systems, ICR plan of uterine cervix cancer, based on recommendation of ICRU38(2D film-based) such as Point A, is still used widely. A 3-dimensional ICR plan based on CT image provides dose-volume histogram(DVH) information of the tumor and normal tissue. In this study, we compared tumor-dose, rectal-dose and bladder-dose through an analysis of DVH between CTV plan and ICRU38 plan based on CT image. Method and Material : We analyzed 11 patients with a cervix cancer who received the ICR of Ir-192 HDR. After 40Gy of external beam radiation therapy, ICR plan was established using PLATO(Nucletron) v.14.2 planing system. CT scan was done to all the patients using CT-simulator(Ultra Z, Philips). We contoured CTV, rectum and bladder on the CT image and established CTV plan which delivers the 100% dose to CTV and ICRU plan which delivers the 100% dose to the point A. Result : The volume$(average{\pm}SD)$ of CTV, rectum and bladder in all of 11 patients is $21.8{\pm}6.6cm^3,\;60.9{\pm}25.0cm^3,\;111.6{\pm}40.1cm^3$ respectively. The volume covered by 100% isodose curve is $126.7{\pm}18.9cm^3$ in ICRU plan and $98.2{\pm}74.5cm^3$ in CTV plan(p=0.0001), respectively. In (On) ICRU planning, $22.0cm^3$ of CTV volume was not covered by 100% isodose curve in one patient whose residual tumor size is greater than 4cm, while more than 100% dose was irradiated unnecessarily to the normal organ of $62.2{\pm}4.8cm^3$ other than the tumor in the remaining 10 patients with a residual tumor less than 4cm in size. Bladder dose recommended by ICRU 38 was $90.1{\pm}21.3%$ and $68.7{\pm}26.6%$ in ICRU plan and in CTV plan respectively(p=0.001) while rectal dose recommended by ICRU 38 was $86.4{\pm}18.3%$ and $76.9{\pm}15.6%$ in ICRU plan and in CTV plan, respectively(p=0.08). Bladder and rectum maximum dose was $137.2{\pm}50.1%,\;101.1{\pm}41.8%$ in ICRU plan and $107.6{\pm}47.9%,\;86.9{\pm}30.8%$ in CTV plan, respectively. Therefore, the radiation dose to normal organ was lower in CTV plan than in ICRU plan. But the normal tissue dose was remarkably higher than a recommended dose in CTV plan in one patient whose residual tumor size was greater than 4cm. The volume of rectum receiving more than 80% isodose (V80rec) was $1.8{\pm}2.4cm^3$ in ICRU plan and $0.7{\pm}1.0cm^3$ in CTV plan(p=0.02). The volume of bladder receiving more than 80% isodose(V80bla) was $12.2{\pm}8.9cm^3$ in ICRU plan and $3.5{\pm}4.1cm^3$ in CTV plan(p=0.005). According to these parameters, CTV plan could also save more normal tissue compared to ICRU38 plan. Conclusion : An unnecessary excessive radiation dose is irradiated to normal tissues within 100% isodose area in the traditional ICRU plan in case of a small size of cervix cancer, but if we use CTV plan based on CT image, the normal tissue dose could be reduced remarkably without a compromise of tumor dose. However, in a large tumor case, we need more research on an effective 3D-planing to reduce the normal tissue dose.

• Journal of Korean Society of Transportation
• /
• v.23 no.7 s.85
• /
• pp.159-163
• /
• 2005

The propriety between suppliers and demanders in geometric design is very important. Although the final purpose of constructing roads is to concern about the driver s comfort, unfortunately, it has not been considered so far. We've considered the regularity and quickness in considering driver's comfort but there should be considered the safety for the accident as well. If drivers are appeared to be more speeding than designer's intention, there will be needed some supplements to increase the safety rate for the roads. Even if both an upward and downward section are supposed to exist at the same time for solid geometry of the roads like this, it is true that the recent design for the 3-D solid geometry section has been done as flat 2-D and the minimum plane curve radius and the maximum cant have been decided just by calculating without considering operating speed between an upward and downward section at the same point. In this investigation, thus, I'd like to calculate the safety of the cant by considering the speed features of the solid geometry for the first lane of four lane rural roads. To begin with, we investigated the driving speed of the car, which is not been influenced by a preceding car to analyze the influence of the geometrical structure by using Nc-97. Secondly, we statistically analyzed the driving features of the solid geometry after comparing the 6 sections, that is, measuring the driving speed feature at 12 points and combining the influence of the vertical geometry and plane geometry to the driving speed of the plane curve which was researched before. Finally, we estimated the value of cant which considers the driving speed not by using it which has applied uniformly without considering it properly, though there were some differences between a designed speed and driving speed through the result of the basic statistical analysis but by introducing the new safety rate rule, a notion of ${\alpha}$. As a result of the research, we could see the driving features of the car and suggest the safety rate which considers these. For considering the maximum cant, if we apply the safety rate, the result of this experiment, which considers 3-D solid geometry, there'll be the improvement of the driver's safety for designing roads. In addition, after collecting and analyzing the data for the road sections which have various geometrical structures by expanding this experiment it is considered that there should be developed the models which considers 3-D solid geometry.

• Korean Journal of Cognitive Science
• /
• v.15 no.2
• /
• pp.1-15
• /
• 2004

The structure of sensibility from motion was developed for the purpose of understanding relationship between sensibilities and physical factors to apply it to dynamic visual display. Seventy adjectives were collected by assessing adequacy to express sensibilities from motion and reporting sensibilities recalled from dynamic displays with achromatic color. Various motion displays with a moving single dot were rated according to the degree of sensibility corresponding to each adjective, on the basis of the Semantic Differential (SD) method. The results of assessment were analyzed by means of the factor analysis to reduce 70 words into 19 fundamental sensibilities from motion. The Multidimensional Scaling (MDS) technique constructed the sensibility space in motion, in which 19 sensibilities were scattered with two dimensions, active-passive and bright-dark Motion types systemically varied in kinematic factors were placed on the two-dimensional space of motion sensibility, in order to analyze important variables affecting sensibility from motion. Patterns of placement indicate that speed and both of cycle and amplitude in trajectories tend to partially determine sensibility. Although color and motion affected sensibility according to the in dimensions, it seemed that combination of motion and color made each have dominant effect individually in a certain sensibility dimension, motion to active-passive and color to bright-dark.

• Journal of Global Scholars of Marketing Science
• /
• v.20 no.2
• /
• pp.164-172
• /
• 2010

This study reviews the influence of culture in interpersonal servicescapes by examining the restaurant retail setting. Two cultures (Canada and France) are surveyed in order to better understand their retail expectations towards interpersonal servicescapes. Using Hofstede's (1991) cultural dimensions to explain some of the differences between Canadian and French restaurant patrons, this study demonstrates a potentially interesting research avenue in the field of cross-cultural interpersonal services marketing. It demonstrates that cultural dimensions do not operate independently but interdependently. Understanding this can help retailers better explain complex service interactions between countries that may appear similar in terms of various socio-demographic features. In this exploratory research, a measure via exploratory factor analysis was developed, one that encompasses both the physical and service aspects common to interpersonal servicescape by using personality traits. This measure was tested in order to better understand the service expectations between two cultures, Canada and France. Five dimensional structures were uncovered in both cultures but with different traits and groupings. The differences between the traits uncovered and the overall Canadian and French personality structures find some explanation using Hofstede's (1991) cultural dimensions. The results of this survey point to a possible explanation as to why when services are transferred between cultures, the perceptions of them can be different and sometimes even lead to service failure. There are clearly some cultural differences between the Canadian and French consumers and their overall expectations regarding their consumption experience. Reviewing the first factor of the French and Canadian personality structures shows that the individualist/collectivist differences are apparent between the Canadian and the French cultures. The second dimension also has quite a few traits in common, five, all of which have the personal treatment aspect of the restaurant experience that a service provider would be responsible for: polite, respectful, and dedicated. Notable is that the French dimension does not include the authenticity or the hospitable aspect of the experience but includes even more features that are inherent to the personal interaction, such as charming and courteous. The third dimension of the Canadian and French structures reflects completely different expectations. Whereas the French dimension centers around energy and enthusiasm, the Canadian version is more laid-back and relaxed. There is extroversion in the French dimension to introversion in the Canadian dimension. This could be explained by differences on the Uncertainty Avoidance dimension as outlined by Hofstede (1991). The fourth dimension seems to confirm previously outlined cultural differences. Whereas Canadians, being a bit lower on uncertainty avoidance and power distance, prefer an intimate and private experience, the French continue to expect extraversion and inclusive features to their experience. The fifth dimension is in the French personality structure a clear expression of the high power distance society, where the roles of the players in the restaurant experience are clearly defined and the rules of engagement preserved. This study demonstrates that different cultures clearly do relate to different expectations regarding interpersonal services. This is apparent in the dimensions that come up in both the French and the Canadian personality structures, not only in terms of how different they are but also in with which cultural dimensions these can be explained. For interpersonal servicescapes, the use of personality traits is interesting as it allows for both physical and service features to be accounted for. Furthermore, the social component inherent to interpersonal servicescapes surfaces in most of the dimensions of the service personality structures. The quality of social exchanges is extremely important, and this even more so in cross-cultural situations, where the expec tations regarding the service experience may vary. As demonstrated by this research and using Hofstede's (1991) paradigm, not all societies will have the same expectations pertaining to the interpersonal services. Furthermore, the traditions surrounding the type of service can also have an impact on the service evaluations and differ between countries and cultures. However, using personality traits may also allow for retailers to see which service traits are common to two or more cultures where they seek to be present, and focus on these in the offering. The findings demonstrate the importance of the individualist and collectivist dimension for interpersonal servicescapes. This difference between the French and the Canadian personality structure is apparent in the most dominant dimension as well as within others. The findings are a step in explaining how retailers can transfer and then measure interpersonal services across cultures.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.1
• /
• pp.58-64
• /
• 2011

Objective: The 3-dimensional reconstruction method with resolution recovery modeling has advantages of high spatial resolution and contrast because of its precise modeling of spatial blurring according to the distance from detector plane. The aim of this study was to evaluate one of the resolution recovery reconstruction methods (Astonish, Philips Medical), compare it to other iterative reconstructions, and verify its clinical usefulness. Materials and Methods: NEMA IEC PET body phantom and Flanges Jaszczak ECT phantom (Data Spectrum Corp., USA) studies were performed using Skylight SPECT (Philips) system under four different conditions; short or long (2 times of short) radius, and half or full (40 kcts/frame) acquisition counts. Astonish reconstruction method was compared with two other iterative reconstructions; MLEM and 3D-OSEM which vendor supplied. For quantitative analysis, the contrast ratios obtained from IEC phantom test were compared. Reconstruction parameters were determined by optimization study using graph of contrast ratio versus background variability. The qualitative comparison was performed with Jaszczak ECT phantom and human myocardial data. Results: The overall contrast ratio was higher with Astonish than the others. For the largest hot sphere of 37 mm diameter, Astonish showed about 27.1% and 17.4% higher contrast ratio than MLEM and 3D-OSEM, in short radius study. For long radius, Astonish showed about 40.5% and 32.6% higher contrast ratio than MLEM and 3D-OSEM. The effect of acquired counts was insignificant. In the qualitative studies with Jaszczak phantom and human myocardial data, Astonish showed the best image quality. Conclusion: In this study, we have found out that Astonish can provide more reliable clinical results by better image quality compared to other iterative reconstruction methods. Although further clinical studies are required, Astonish would be used in clinics with confidence for enhancement of images.

• Journal of the Korean Geotechnical Society
• /
• v.32 no.10
• /
• pp.41-53
• /
• 2016

Stability of the braced earth wall in the composite ground, which is composed of the jointed base rocks and the soil strata depends on the earth pressure acting on it. In most cases, the earth pressure is calculated by the empirical method, in which base rocks are considered as a soil strata with the shear strength parameters of base rocks. In this case the effect of the joint dips of the jointed base rocks is ignored. Therefore, the calculated earth pressure is smaller than the actual earth pressure. In this study, the magnitude and the distribution of the earth pressure acting on the braced wall in the composite ground depending on the joint dips of the base rocks and the ratio of soil strata and base rocks were experimentally studied. Two dimensional large-scale model tests were conducted in a large scale test facility (height 3.0 m, length 3.0 m and width 0.5 m) by installing 10 supports in a scale of 1/14.5. The test ground was presumed with the base rock ratio of the composite ground of 65%:35% and 50%:50% and with the joint dips for each base rock layer, $0^{\circ}$, $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$, respectively. And then finite element analyses were performed in the same condition. As results, the earth pressure on the braced wall increased as the base rock layer's joint dips became larger. And earth pressure at the rock layer increased as the rock rate became larger. The largest earth pressure was measured when the base rock rate was 50% (R50) and the rock layer's joint dips was $60^{\circ}$. Based on these results, a formular for the calculation of the earth pressure in the composite ground could be suggested. Distribution of earth pressure was idealized in a quadrangular form, in which the magnitude and the position of peak earth pressure depended on the rock ratio and the joint dips.

• Progress in Medical Physics
• /
• v.14 no.2
• /
• pp.90-98
• /
• 2003

Purpose : A new virtual simulation technique for craniospinal irradiation (CSI) that uses a CT-simulator was developed to improve the accuracy of field and shielding placement as well as patient positioning. Materials and Methods : A CT simulator (CT-SIM) and a 3-D conformal radiation treatment planning system (3D-CRT) were used to develop CSI. The head and neck were immobilized with a thermoplastic mask while the rest of the body was immobilized with a Vac-Loc. A volumetric image was then obtained with the CT simulator. In order to improve the reproducibility of the setup, datum lines and points were marked on the head and body. Virtual fluoroscopy was performed with the removal of visual obstacles, such as the treatment table or immobilization devices. After virtual simulation, the treatment isocenters of each field were marked on the body and on the immobilization devices at the conventional simulation room. Each treatment fields was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR) and digitally composited radiography (DCR) images from virtual simulation. Port verification films from the first treatment were also compared with the DRR/DCR images for geometric verification. Results : We successfully performed virtual simulations on 11 CSI patients by CT-SIM. It took less than 20 minutes to affix the immobilization devices and to obtain the volumetric images of the entire body. In the absence of the patient, virtual simulation of all fields took 20 min. The DRRs were in agreement with simulation films to within 5 mm. This not only reducee inconveniences to the patients, but also eliminated position-shift variables attendant during the long conventional simulation process. In addition, by obtaining CT volumetric image, critical organs, such as the eyes and the spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. Differences between the DRRs and the portal films were less than 3 m in the vertebral contour. Conclusion : Our analysis showed that CT simulation of craniospinal fields was accurate. In addition, CT simulation reduced the duration of the patient's immobility. During the planning process. This technique can improve accuracy in field placement and shielding by using three-dimensional CT-aided localization of critical and target structures. Overall, it has improved staff efficiency and resource utilization by standard protocol for craniospinal irradiation.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.11 no.4
• /
• pp.192-205
• /
• 2009

The unexpected wind over the Mt. Hwawang on 9 February 2009 was deadly when many spectators were watching a traditional event to burn dried grasses and the fire went out of control due to the wind. We analyzed the fatal wind based on wind flow simulations over a digitized complex terrain of the mountain with a localized heating area using a three dimensional computational fluid dynamics model, CFD_NIMR_SNU (Computational Fluid Dynamics_National Institute of Meteorological Research_Seoul National University). Three levels of fire intensity were simulated: no fire, $300^{\circ}C$ and $600^{\circ}C$ of surface temperature at the site on fire. The surface heat accelerated vertical wind speed by as much as $0.7\;m\;s^{-1}$ (for $300^{\circ}C$) and $1.1\;m\;s^{-1}$ (for $600^{\circ}C$) at the center of the fire. Turbulent kinetic energy was increased by the heat itself and by the increased mechanical force, which in turn was generated by the thermal convection. The heating together with the complex terrain and strong boundary wind induced the unexpected high wind conditions with turbulence at the mountain. The CFD_NIMR_SNU model provided valuable analysis data to understand the consequences of the fatal mountain fire. It is suggested that the place of fire was calm at the time of the fire setting due to the elevated terrain of the windward side. The suppression of wind was easily reversed when there was fire, which caused updraft of hot air by the fire and the strong boundary wind. The strong boundary wind in conjunction with the fire event caused the strong turbulence, resulting in many fire casualties. The model can be utilized in turbulence forecasting over a small area due to surface fire in conjunction with a mesoscale weather model to help fire prevention at the field.