• Progress in Medical Physics
• /
• v.21 no.1
• /
• pp.93-98
• /
• 2010

The aim of this work was to establish the methodology for event positioning by measuring depth of interaction (DOI) information and to evaluate the system sensitivity and spatial resolution of the new detector for I-125 and Tc-99m imaging. For this purpose, a Monte Carlo simulation tool, DETECT2000 and GATE were used to model the energy deposition and light distribution in the detector and to validate this approach. Our proposed detector module consists of a monolithic CsI(Tl) crystal with dimensions of $50.0{\times}50.0{\times}3.0\;mm^3$. The results of simulation demonstrated that the resolution is less than 1.5 mm for both I-125 and Tc-99m. The main advantage of the proposed detector module is that by using 3 mm thick CsI(Tl) with maximum-likelihood position-estimation (MLPE) method, high resolution I-125 imaging and high sensitivity Tc-99m imaging are possible. In this paper, we proved that our new detector to be a reliable design as a detector for a multi-energy SPECT.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.172-172
• /
• 2011

The interaction between land surface and atmosphere is essentially affected by hydrometeorological variables including soil moisture. Accurate estimation of soil moisture at spatial and temporal scales is crucial to better understand its roles to the weather systems. The KLDAS(Korea Land Data Assimilation System) is a regional, specifically Korea peninsula land surface information systems. As other prior land data assimilation systems, this can provide initial soil field information which can be used in atmospheric simulations. For this study, as an enabling high-resolution tool, weather research and forecasting(WRF-ARW) model is applied to produce precipitation data using GFS(Global Forecast System) with GFS embedded and KLDAS soil moisture information as initialization data. WRF-ARW generates precipitation data for a specific region using different parameters in physics options. The produced precipitation data will be employed for simulations of Hydrological Models such as HEC(Hydrologic Engineering Center) - HMS(Hydrologic Modeling System) as predefined input data for selected regional water responses. The purpose of this study is to show the impact of a hydrometeorological variable such as soil moisture in KLDAS on hydrological consequences in Korea peninsula. The study region, Chongmi River Basin, is located in the center of Korea Peninsular. This has 60.8Km river length and 17.01% slope. This region mostly consists of farming field however the chosen study area placed in mountainous area. The length of river basin perimeter is 185Km and the average width of river is 9.53 meter with 676 meter highest elevation in this region. We have four different observation locations : Sulsung, Taepyung, Samjook, and Sangkeug observatoriesn, This watershed is selected as a tentative research location and continuously studied for getting hydrological effects from land surface information. Simulations for a real regional storm case(June 17~ June 25, 2006) are executed. WRF-ARW for this case study used WSM6 as a micro physics, Kain-Fritcsch Scheme for cumulus scheme, and YSU scheme for planetary boundary layer. The results of WRF simulations generate excellent precipitation data in terms of peak precipitation and date, and the pattern of daily precipitation for four locations. For Sankeug observatory, WRF overestimated precipitation approximately 100 mm/day on July 17, 2006. Taepyung and Samjook display that WRF produced either with KLDAS or with GFS embedded initial soil moisture data higher precipitation amounts compared to observation. Results and discussions in detail on accuracy of prediction using formerly mentioned manners are going to be presented in 2011 Annual Conference of the Korean Society of Hazard Mitigation.

• The Journal of the Korea Contents Association
• /
• v.20 no.8
• /
• pp.315-326
• /
• 2020

Corporate efforts to build strong brands have made consumers interested in brand love. In the field of brand love, however, there is a lack of systematic research on the multidimensionality of the concept of brand love and on the scale development to measure it. Thus, based on the methodological research design of Churchill(1979) and DeVellis(1991), this study explored properties of brand love and classified them into two levels - 'emotion' and 'relationship' - and generated corresponding measurement items. To do this, the research was conducted in a total of eight stages, including preliminary studies such as literature review, open surveys, and in-depth interviews, as well as the main study process in which the factors were analyzed step by step. As a result, the level of emotion appeared to have five subcomponents (self-esteem, warmth, interest, responsibility, pleasure) with 19 items, and the level of relationship - three subcomponents (unchanging, sharing/supporting, understanding) with 11 items, adding up to a total of 30 measurement items for brand love with reliability, convergent and discriminant validity, and nomological validity. Additionally, we intended to expand the scope of research related to brand love by presenting the result model of organic interaction between the concepts that constitute brand love and proposing '4 categories of brand love strength' based on it.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.240-250
• /
• 2020

This study explores the process of transitional career choice for North Korean defectors who are successfully living their lives after transition to a different system labor market. To achieve this study purpose, what is the process of transitional career choice for North Korean defectors due to the system transition? At present, he (Ed- who is he?) has a subjective sense of success in his professional life and conducted in depth interviews with three men and eight women as objects that can explain the process of experience in rich and detailed ways. To this end, the author interviewed three men and eight women who are satisfied with their current job and analyzed them with the grounded theory method proposed by Strauss & Corbin (1998). As a result, the paradigm model was derived from the central phenomenon of 'conversion of perspective', and the core category was 'conversion of perspective and challenge new career'. The transitional career choice process was derived into four stages according to the flow of time and interaction as 'reality recognition stage', 'active change recognition stage', 'support and coping strategy stage', and 'growth stage' and positive reflections from transitional learning and potential factors of planned chance skills were found.

• The Journal of the Korea Contents Association
• /
• v.12 no.4
• /
• pp.510-519
• /
• 2012

The purpose of this study is to investigate how interactions and affective factors are influencing on-line English Grammar courses of higher education. This study addressed the following questions: (1) How are the interactions going in on-line English Grammar courses? (2) Are affective factors influencing effective learning in on-line English Grammar courses? The questionnaire was conducted on 170 college students who have taken on-line English course of K University. The data analysis of 300 college students' responses on their courses showed that e-learning has both positive and negative effects compared to face to face classroom instructions. Analysis showed that the percentage of students who have got negative opinions on e-learning was 17%, while that of students who have got positive opinions was 49.3%. The percentage of those in the middle was 33.3%. However, results demonstrated that immediate feedback and affective factors could be facilitated through Q&A bulletin and feedback program for completing on-line learning. Negative effects of on-line learning can be solved by a planned and well-supported on-line approach that includes a theory-based instructional model rather than the new method replaced by 'blended learning' that combines face-to-face classroom instruction with on-line learning.

• Structural Engineering and Mechanics
• /
• v.75 no.4
• /
• pp.507-518
• /
• 2020

With the rapid development of rail transit, rail transit noise needs to be paid more and more attention. In order to accurately and effectively analyze the characteristics of low-frequency noise, a prediction model of vibration of box girder was established based on the hybrid FE-SEA method. When the train speed is 140 km/h, 200 km/h and 250 km/h, the vibration and noise of the box girder induced by the vertical wheel-rail interaction in the frequency range of 20-500 Hz are analyzed. Detailed analysis of the energy level, sound pressure contribution, modal analysis and vibration loss power of each slab at the operating speed of 140 km /h. The results show that: (1) When the train runs at a speed of 140km/h, the roof contributes more to the sound pressure at the far sound field point. Analyzing the frequency range from 20 to 500 Hz: The top plate plays a very important role in controlling sound pressure, contributing up to 70% of the sound pressure at peak frequencies. (2) When the train is traveling at various speeds, the maximum amplitude of structural vibration and noise generated by the viaduct occurs at 50 Hz. The vibration acceleration of the box beam at the far field point and near field point is mainly concentrated in the frequency range of 31.5-100 Hz, which is consistent with the dominant frequency band of wheel-rail force. Therefore, the main frequency of reducing the vibration and noise of the box beam is 31.5-100 Hz. (3) The vibration energy level and sound pressure level of the box bridge at different speeds are basically the same. The laws of vibration energy and sound pressure follow the rules below: web

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.9
• /
• pp.623-629
• /
• 2011

The adsorption characteristics of tricyclazole by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of tricyclazole were carried out at 298, 308 and 318 K, using aqueous solutions with 250, 500 and 1,000 mg/L initial concentration of tricyclazole. It was established that the adsorption equilibrium of tricyclazole on granular activated carbon was successfully fitted by Freundlich isotherm equation at 298 K. The pseudo first order and pseudo second order models were used to evaluate the kinetic data and the pseudo second order kinetic model was the best with good correlation. Values of the rate constant ($k_2$) have been calculated as 0.1076, 0.0531, and 0.0309 g/mg h at 250, 500 and 1,000 mg/L initial concentration of tricyclazole, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The positive value for enthalpy, -66.43 kJ/mol indicated that adsorption interaction of tricyclazole on activated carbon was an exothermic process. The estimated values for standard free energy were -5.08~-8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a exothermic process.

• The Journal of Korean Society for Radiation Therapy
• /
• v.14 no.1
• /
• pp.175-186
• /
• 2002

The purpose of this study is directly measure and evaluate about absorbed dose change according to nominal energy and electron cone or medical accelerator on isodose curve, percentage depth dose, contaminated X-ray, inhomogeneous tissue, oblique surface and irradiation on intracavitary that electron beam with high energy distributed in tissue, and it settled standard data of hish energy electron beam treatment, and offer to exactly data for new dote distribution modeling study based on experimental resuls and theory. Electron beam with hish energy of $6{\sim}20$ MeV is used that generated from medical linear accelerator (Clinac 2100C/D, Varian) for the experiment, andwater phantom and Farmer chamber md Markus chamber und for absorbe d dose measurement of electron beam, and standard absorbed dose is calculated by standard measurements of International Atomic Energy Agency(IAEA) TRS 277. Dose analyzer (700i dose distribution analyzer, Wellhofer), film (X-OmatV, Kodak), external cone, intracavitary cone, cork, animal compact bone and air were used for don distribution measurement. As the results of absorbed dose ratio increased while irradiation field was increased, it appeared maximum at some irradiation field size and decreased though irradiation field size was more increased, and it decreased greatly while energy of electron beam was increased, and scattered dose on wall of electron cone was the cause. In percentage depth dose curve of electron beam, Effective depth dose(R80) for nominal energy of 6, 9, 12, 16 and 20 MeV are 1.85, 2.93, 4.07, 5.37 and 6.53 cm respectively, which seems to be one third of electron beam energy (MeV). Contaminated X-ray was generated from interaction between electron beam with high energy and material, and it was about $0.3{\sim}2.3\%$ of maximum dose and increased with increasing energy. Change of depth dose ratio of electron beam was compared with theory by Monte Carlo simulation, and calculation and measured value by Pencil beam model reciprocally, and percentage depth dose and measured value by Pencil beam were agreed almost, however, there were a little lack on build up area and error increased in pendulum and multi treatment since there was no contaminated X-ray part. Percentage depth dose calculated by Monte Carlo simulation appeared to be less from all part except maximum dose area from the curve. The change of percentage depth dose by inhomogeneous tissue, maximum range after penetration the 1 cm bone was moved 1 cm toward to surface then polystyrene phantom. In case of 1 cm and 2 cm cork, it was moved 0.5 cm and 1 cm toward to depth, respectively. In case of air, practical range was extended toward depth without energy loss. Irradiation on intracavitary is using straight and beveled type cones of 2.5, 3.0, 3.5 $cm{\phi}$, and maximum and effective $80\%$ dose depth increases while electron beam energy and size of electron cone increase. In case of contaminated X-ray, as the energy increase, straight type cones were more highly appeared then beveled type. The output factor of intracavitary small field electron cone was $15{\sim}86\%$ of standard external electron cone($15{\times}15cm^2$) and straight type was slightly higher then beveled type.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.5
• /
• pp.179-190
• /
• 2020

This research analyses the financial characteristics of corporate R&D intensity in the Korean capital market. It is important to pay greater attention to this subject, given the current situation of the shortage of core components domestically in Korea. Three hypotheses are postulated to investigate the financial factors of R&D investments for KOSDAQ-listed firms during the post-era of the global financial turmoil. By applying a conditional quantile regression (CQR) model, three variables included R&D intensity in the previous year (Lag_RD), the squared term of Lag_RD, and interaction between the high-tech sector and Lag_Rd, reveal significant effects on the current R&D ratio. Whereas more than half of the total variables show variable impacts between firms with higher and lower R&D intensity, only Lag_RD and squared term of Lag_RD were found to be significant. It is expected that these results may contribute to being financial catalysts for an optimal level of R&D expenditures, thereby maximizing firm value for shareholders in KOSDAQ-listed firms.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.23 no.2
• /
• pp.53-60
• /
• 2015

Newly, nutrients recovery by bioconversion in the swine waste which caused serious problems due to its high organic fraction and content of nutrients such as phosphorus and nitrogen is viewed as a considerable approach since it produces valuable product as well as recycling of resources. Consequently, it is necessary to find new methods to treat swine waste. One possible solution to this problem is to use this potential pollutant as a growth substrate for economically valuable products. The study for the fundamental improvement of bioconversion efficiency by finding optimum growth conditions using statistical models and biotechnology was performed. A novel approach to utilize swine waste by cultivating mycelia of the mushroom Phellinus linteus are described. A central composite face-centered design (CCF) for the experiments was used to develop empirical model providing a quantitative interpretation of the relationships among the three variables, which were substrate concentration, pH, and temperature. The maximal radial extension rate (2.78mm/d) of P.linteus was determined under the condition of 5.0 g COD/L, pH 5.0, and temperature $29.7^{\circ}C$. The results of this study suggest that swine waste could be utilized as a growth substrate for the cultivation of mushroom mycelia enhancing an efficiency of utilizing this by-product of the livestock industry.