• Radiation Oncology Journal
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• v.2 no.1
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• pp.149-153
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• 1984

Postoperative radiotherapy of breast cancer makes it possible to reduce loco-regional recurrence of breast cancer. The treatment technique, which can reduce the low-dose region at the junction and lung, is required. To produce proper dose distribution of internal mammary chain and chest wall, authors tried to find the method to expose $^{60}Co\;\gamma-ray$ on internal mammary region and 7MeV electron on chest wall. Exposure time of $^{60}Co\;\gamma$ and monitor unit of 9MeV were selected so that dose of $^{60}Co$ at 4cm depth was the same as that of 7Mev electron at $80\%$ dose depth. The position and direction of electron beam were changed for $^{60}Co$ beam: $0^{\circ},\;5^{\circ}$ for 0cm seperation; $0^{\circ},\;5^{\circ},\;10^{\circ}$ for 0.5cm seperation; $5^{\circ},\;10^{\circ},\;15^{\circ}$ for 1cm seperation. The results are as followings. 1. When the seperation of two fields was increased, dose on the axis of $^{60}Co$ beam was increased and dose at the junction region decreased while the volume of lung to be exposed to high dose and hot spot size were irregularly changed. 2. The dose distribution in the target volume of internal mammary and chest wall was most ideal when the seperation of two fields was $0\~0.5cm$ and the direction of electron beam was parallel to $^{60}Co$ beam.

• Smart Structures and Systems
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• v.17 no.6
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• pp.1087-1105
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• 2016

Traffic load and volume is one of the most important physical quantities for bridge safety evaluation and maintenance strategies formulation. This paper aims to conduct the statistical analysis of traffic volume information and the multimodal modeling of gross vehicle weight (GVW) based on the monitoring data obtained from the weigh-in-motion (WIM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. A genetic algorithm (GA)-based mixture parameter estimation approach is developed for derivation of the unknown mixture parameters in mixed distribution models. The statistical analysis of one-year WIM data is firstly performed according to the vehicle type, single axle weight, and GVW. The probability density function (PDF) and cumulative distribution function (CDF) of the GVW data of selected vehicle types are then formulated by use of three kinds of finite mixed distributions (normal, lognormal and Weibull). The mixture parameters are determined by use of the proposed GA-based method. The results indicate that the stochastic properties of the GVW data acquired from the field-instrumented WIM sensors are effectively characterized by the method of finite mixture distributions in conjunction with the proposed GA-based mixture parameter identification algorithm. Moreover, it is revealed that the Weibull mixture distribution is relatively superior in modeling of the WIM data on the basis of the calculated Akaike's information criterion (AIC) values.

• Journal of Korean Society on Water Environment
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• v.38 no.3
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• pp.133-142
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• 2022

Natural organic matter (NOM) is a heterogeneous mixture of organic matter with various polarities and molecular weights in an aquatic environment. This study investigated the effects of separation conditions (resin volume, organic matter, etc.) and the repeated use of the resin for the fractionation of organic components in the DAX resin fractionation method. The distribution characteristics of the organic components ((hydrophilic [Hi], hydrophobic acid [HoA], and hydrophobic neutral [HoN]) under the derived fractionation conditions were also analyzed. Constant fractionation results (i.e. HoA/Hi ratio) were obtained in the column capacity factor (i.e. the packed resin volume) in the range of 50 to 100. The resin-packed column maintained constant separation efficiency for up to two repeated uses. The above conditions were applied to wastewater and stream water samples (before and after rainfall). The results showed that the concentration of organic matter in the wastewater effluent was 2-15 times lower with an increased ratio of hydrophilicity to hydrophobicity (i.e. Ho/Hi) compared to the influent depending on the industrial wastewater classification. Particularly, HoN was found to have a high content distribution, 10.2-50.4% of the total dissolved organic matter (DOM), in the effluents. For the stream water, the content of Hi or HoN increased significantly after rainfall, suggesting a correlation with the distribution characteristics of pollutants from the stream watershed. The results provide useful data to enhance the reliability of the DAX resin fractionation and its application to environmental samples.

• Journal of Ocean Engineering and Technology
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• v.17 no.5 s.54
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• pp.32-38
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• 2003

This study investigates the distribution characteristics and relationship of water quality, and analyzes the spatial and temporal variation and distribution of the pollutant loads at Yeong-il Bay. The results of these analysis, the concentrations of nutrient loads (T-N and T-P), both appeared to be at the maximum value in November, while most small values were taken in May for the T-N, and in August for the T-P. For COD, the maximum concentration was in August, which has much precipitation during the same season, T-N was at the mean, and T-P was at the minimum value. Using the cluster analysis to develop the division of the sea basin by the dendrogram, before and after construction of Pohang New-port, the variation characteristics of water quality of Yeong-il Bay were discussed. The in flowing pollutant loads were transported to the landward by the high-density salinity water volume of the bottom layer therefore, it formed nutrient trap or coastal trapping areas of the pollutant load. By this mechanism, it is clear that the water volume with high-density nutrient exists on both sides of the Pohang New-port. Thus, the sea basins increasing concentration of the pollutant load at Yeong-il Bay are most prevalent at Hyeong-san estuary, the Pohang Old, and New-port. To improve water quality of this sea basin, the reduction of these nutrients loads should be the highest priority.

• Steel and Composite Structures
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• v.18 no.6
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• pp.1493-1515
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• 2015

A new refined hyperbolic shear deformation theory (RHSDT), which involves only four unknown functions as against five in case of other shear deformation theories, is presented for the thermoelastic bending analysis of functionally graded sandwich plates. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The sandwich plate faces are assumed to have isotropic, two-constituent material distribution through the thickness, and the modulus of elasticity, Poisson's ratio of the faces, and thermal expansion coefficients are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. Several kinds of sandwich plates are used taking into account the symmetry of the plate and the thickness of each layer. The influences played by the transverse shear deformation, thermal load, plate aspect ratio and volume fraction distribution are studied. Numerical results for deflections and stresses of functionally graded metal-ceramic plates are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of functionally graded plates.

• Magazine of the Korean Society of Agricultural Engineers
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• v.8 no.1
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• pp.1011-1034
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• 1966

This thesis is the final report which has long been studied by the author to obtain the design basis for various hydrological constructions with the specific system suitable to the natural environmental conditions in Korea. This report is divided into two parts: one is to estimate runoff volume from watersheds and the other to estimate the peak discharge for a single storm. According to the result of observed runoff record from watersheds, it is known that Kajiyama formula is useful instrument in estimating runoff volume from watersheds in this country. But it has been found that this formula shows us 20-30% less than the actual flow. Therefore, when wihed to bring a better result, the watershed characteristics coefficient in this formula, that is, f-value, should be corrected to 0.5-0.8. As for the method to estimate peak discharge from drainage basin, the author proposes to classify it in two ways; one is small size watershed and the other large size watershed. The maximum -flood discharge rate $Q_p$ and time to peak Pt obtained from the observed record on the small size watershed are compared by various methods and formulas which are based upon the modern hydrological knowledge. But it was fou.d that it. was not a satisfied result. Therefore, the author proposes. tocomputate $Q_p$, to present 4.0-5.0% for the total runoff volume ${\Sigma}Q$.${\Sigma}Q$ is computed under the assumption of 30mm 103s in watershed per day and to change the theoritical total flow volume to one hour dura tion total flow rate when design daily storm is given. Time to peak Pt is derived from three parameters which are u,w,k. These are computed by relationship between total runoff volume (ha-m unit)and $Q_p$. (C.M.S. unit). Finally, the author checked out these results obtained from 51 hydrographs and got a satisfied result. Therefore the author suggested the model of design dimensionless unit-hydrograph. And the author believes that this model will be much available at none runoff record river site. In the large size watersheds in Korea when the maximum discharge occurs, the effective rainfall is two consequtive stormy days. So the loss in watershed was assutned as 6Omm/2days,and the author proposed 3-hour-daration hydrograph flow distribution percentage. This distribution percentage will be sure to form the hydrograph coordinate.

• Radiation Oncology Journal
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• v.38 no.1
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• pp.52-59
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• 2020

Purpose: To evaluate and compare the feasibilities of magnetic resonance (MR) image-based planning using synthetic computed tomography (sCT) versus CT (pCT)-based planning in helical tomotherapy for prostate cancer. Materials and Methods: A retrospective evaluation was performed in 16 patients with prostate cancer who had been treated with helical tomotherapy. MR images were acquired using a dedicated therapy sequence; sCT images were generated using magnetic resonance for calculating attenuation (MRCAT). The three-dimensional dose distribution according to sCT was recalculated using a previously optimized plan and was compared with the doses calculated using pCT. Results: The mean planning target volume doses calculated by sCT and pCT differed by 0.65% ± 1.11% (p = 0.03). Three-dimensional gamma analysis at a 2%/2 mm dose difference/distance to agreement yielded a pass rate of 0.976 (range, 0.658 to 0.986). Conclusion: The dose distribution results obtained using tomotherapy from MR-only simulations were in good agreement with the dose distribution results from simulation CT, with mean dose differences of less than 1% for target volume and normal organs in patients with prostate cancer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.12
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• pp.588-593
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• 2014

To maintain a negative pressure, the supply, exhaust airvolume are adjusted by setting volume damper and the infiltration through leakage area of the door between rooms in biosafety laboratory. Multizone simulation is useful way to predict room pressure, supply and exhaust air volume. But in a particular room, local change such as airflow and contaminants concentration distribution can not be evaluated unfortunately. Through this study, a coupled multizone and CFD simulation was performed, indoor air flow and local contaminants concentration distribution in a particular room of BSL lab are predicted. The results show that all zones of BSL lab are well ventilated by unidirectional flow without local stagnation. In addition, in case that unexpected biohazard is occured in BSL lab, multizone simulation results about the spread of pollutants along movement of the occupant also show that contaminants concentration is removing totally without the spread of the outside. In conclusion, a coupled multizone and CFD simulation can be applied to interpret differential pressure in room and local change of physical quantity in a particular room such as airflow and Influenza A contaminants concentration distribution. This simulation method is useful to enhance the reliability and accuracy of biosafety laboratory design.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.288-301
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• 2002

A vacuum freeze drying experiment of skim milk solution in a cylindrical container is conducted to investigate the multi-dimensional drying characteristics of the process during the primary drying stage. Temperature histories at several positions are measured under the same process condition that is carefully controlled. Then the measured temperature histories at different positions are combined to produce instantaneous temperature distribution fields inside the cylindrical container. Along with the temperature measurement, the mass reduction history of the skim milk solution is also measured. From the measured temperature distribution curved configurations of sublimation interfaces and 2-dimensional heat transfer is inferred. The freeze drying under the present experimental setup is simulated with a calculation program that is based on a finite volume method with a moving grid system. Good agreements between the numerical and experimental results are observed. The present experimental results and the numerical approaches can be useful information in developing the analysis tools for practical vacuum freeze drying processes.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.254-261
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• 1994

This study was conducted to investigate and interpret the stand structure of Korean Red pine (Pinus densiflora) stands in Kangwon province, so as to provide basics information for effective forest management. The results obtained in this study were as follows : 1. Number of trees distribution for each diameter class have left nonsymmetrical in Gosung districts, but symmetrical distribution in Pyungchang districts. 2. Height curve for D.B.H. Distribution becames liner shape in Pyungchang districts that more higher than Gosung districts. 3. Stand volume and number of trees per ha in Pyungchang districts are higher than Gosung districts. 4. D.B.H. growth increments during recent 5 years at large D.B.H. class has much lager than low D.B.H. class. 5. Total growth increments of D.B.H., height and volume in Pyungchang districts are or the higher than Gosung districts overtimes 15 years later.