• Journal of Sensor Science and Technology
• /
• v.23 no.3
• /
• pp.197-201
• /
• 2014

TEPC (Tissue Equivalent Proportional Counter) was usually used for high LET radiation dosimetry. We developed a prototype TEPC for micro-dosimetry in the range of $0.2{\sim}300 keV/{\mu}m$. And, the simulated site diameter of the TEPC is $2{\mu}m$, of similar size to a cell nucleus. For purposes of characterization the response for high LET radiation of the TEPC has been investigated under 135MeV/u Carbon ions in HIMAC (Heavy Ion Medical Accelerator). We determined the gas multiplication factor and measured the lineal energy spectrum [yd(y)] of 135 MeV/u Carbon ions. The value of the gas multiplication factor was 315 at 700 V bias voltage. As a result of the experiment, we could more understand the performance of the TEPC for high LET (Linear Energy Transfer) radiation. And the procedure of high LET radiation dosimetry using TEPC is established.

• Journal of radiological science and technology
• /
• v.39 no.1
• /
• pp.43-49
• /
• 2016

In this study, equivalent dose and LET (Linear Energy Transfer) calibration of CR-39 SSNTD (Solid State Nuclear Track Detector) were performed using 400 MeV/u C heavy ions in HIMAC (Heavy Ion Medical Accelerator in Chiba) for high LET radiation therapy. The irradiated CR-39 SSNDTs were etched according the etching condition of JAXA (Japan Aerospace Exploration Agency). And the etched SSNTDs were analyzed by using Image J. Determined frequency mean dose (${\bar{y_D}}$)and dose-mean lineal energy (${\bar{y_F}}$)of 400 MeV/u C are about 8.5keV/mm and 10.1 keV/mm, respectively by using the CR-39 SSNTD. This value is very similar to the results calculated by GEANT4 Monte Carlo simulation and measured with TEPC (Tissue Equivalent Proportional Counter) active radiation detector. We could determine the equivalent dose and LET calibration factors of CR-39. And we confirmed that the CR-39 SSNTD was useful for high LET radiation dosimetry in hadron radiotherapy.

• New & Renewable Energy
• /
• v.7 no.2
• /
• pp.18-27
• /
• 2011

Management flexibility to adapt its future actions in response to altered future market conditions can expand the value of an investment opportunity by improving its upside potential without the change in the downside losses. Module manufacturers in solar industry continuously have to decide how much and when its production capacity should be expanded with regards to the demand in the global markets. Either over- or under-investment can cause sunk and/or opportunity costs to the module manufacturers. Option of exercising the additional investments only on favorable opportunities can increase total value of the investment. This paper analyzes the case which shows that the expansion of production capacity with more expandibility can have more value than the rigid plan of capacity expansion. The expansion option value is equivalent to KRW 38.286 billion, thus switching the negative NPV of the initial investment opportunity into the positive value. High volatility and the high growth in the cashflows as the major business features of the renewable energy provide condition where real options can play the crucial role in increasing the investment value as well as in determining the size and timing of capacity expansion in the course of capital budgeting process.

• Nuclear Engineering and Technology
• /
• v.32 no.5
• /
• pp.477-484
• /
• 2000

To estimate the degree of intake of $^{238}$ U and $^{232}$ Th through daily diet, a Korean mixed diet sample was prepared after the investigation of the amount of consumption of the daily diet which corresponds to the age of 20 to 60 years. For the analysis of U and Th, the RNAA method was applied. Two standard reference materials were used for quality control and assurance and the analytical results were compared with a certified value. The determination of U and Th in the Korean mixed diet sample was carried out under the same analytical conditions and procedures with SRM. It is found that the concentration of U and Th in a Korean mixed diet was about 35.4 ppb and 3.4 ppb. From these results, the daily intake of $^{238}$ U and $^{232}$ Th by diet is evaluated to be 6.98 and 0.67 $\mu\textrm{g}$ per day, respectively. Radioactivities related to the intake of $^{238}$ U and $^{232}$ Th were estimated to be about 86 mBq and 27 mBq per person per day and the annual dose equivalents from $^{238}$ U and $^{232}$ Th revealed as 3.18 $\mu$Sv and 0.29 $\mu$Sv per person, respectively.

• Journal of the Korean Wood Science and Technology
• /
• v.50 no.5
• /
• pp.353-364
• /
• 2022

The crystalline domain of thermosetting urea-formaldehyde (UF) resins at low formaldehyde-to-urea (F/U) molar ratios (≤ 1.0) is known to be responsible for their poor performance as wood adhesives. Crystallization has been observed in 1.0 F/U UF resins during the addition reaction stage and at the end of the synthesis process (neat UF resins). The crystallinity and X-ray diffraction (XRD) spectra of the uncured neat UF resins, on the other hand, differed significantly from those of the cured neat UF resins, raising the possibility that their crystal structures were also different. This study demonstrates for the first time that the crystalline domains in 1.0 F/U UF resins generated from uncured and cured samples are identical. Despite having a lower crystallinity value, the synchrotron XRD patterns of purified neat UF resins were equivalent to the XRD patterns of cured neat UF resins. Transmission electron microscope images of the cured UF resins showed that the crystals were lamellar structures. This finding suggests that the crystal at low molar ratio UF resins are isotropic polycrystals with random orientation.

• Wind and Structures
• /
• v.19 no.3
• /
• pp.339-352
• /
• 2014

This paper discusses the appropriate duration for basic gust wind speeds in wind loading codes and standards, and in wind engineering generally. Although various proposed definitions are discussed, the 'moving average' gust duration has been widely accepted internationally. The commonly-specified gust duration of 3-seconds, however, is shown to have a significant effect on the high-frequency end of the spectrum of turbulence, and may not be ideally suited for wind engineering purposes. The effective gust durations measured by commonly-used anemometer types are discussed; these are typically considerably shorter than the 'standard' duration of 3 seconds. Using stationary random process theory, the paper gives expected peak factors, $g_u$, as a function of the non-dimensional parameter ($T/{\tau}$), where T is the sample, or reference, time, and ${\tau}$ is the gust duration, and a non-dimensional mean wind speed, $\bar{U}.T/L_u$, where $\bar{U}$ is a mean wind speed, and $L_u$ is the integral length scale of turbulence. The commonly-used Durst relationship, relating gusts of various durations, is shown to correspond to a particular value of turbulence intensity $I_u$, of 16.5%, and is therefore applicable to particular terrain and height situations, and hence should not be applied universally. The effective frontal areas associated with peak gusts of various durations are discussed; this indicates that a gust of 3 seconds has an equivalent frontal area equal to that of a tall building. Finally a generalized gust response factor format, accounting for fluctuating and resonant along-wind loading of structures, applicable to any code is presented.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.4
• /
• pp.411-420
• /
• 2018

This study presents a revised crackling core model for the description of $UO_2$ sphere oxidation in air atmosphere. For close reproduction of the sigmoid behavior exhibited in $UO_2$ to $U_3O_8$ conversion, the fragmentation effect contributing to the increased reactive surface area and the concept of variable grain conversion time were considered in the model development. Under the assumptions of two-step successive reaction of $UO_2{\rightarrow}U_3O_7{\rightarrow}U_3O_8$ and final grain conversion time equivalent to ten times the initial grain conversion time, the revised model showed good agreement with the experimental data measured at 599 - 674 K and a lowest deviation when compared with Nucleation and Growth model and AutoCatalytic Reaction model. The evaluated activation energy at 100% conversion to $U_3O_8$, $57.6kJ{\cdot}mol^{-1}$, was found to be closer to the experimentally extrapolated value than to the value determined in AutoCatalytic Reaction model, $48.6kJ{\cdot}mol^{-1}$.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.11 no.2
• /
• pp.63-71
• /
• 2005

The purpose of this study is to find the complementary idea of the psychological elements in aesthetic expression of architectural space in the sense of healing. Marks $L\ddot{u}scher$, the swiss psychologist suggested reasonable categories of emotional character according to the couple combinations among Content, Self-Esteem, Confidence, and Liberty. His theory on healing is not only the concept but the practical method to understand and control the conflict between contrary elements of emotion. Compared to the Freud's objective theory of cause and consequence, his idea is focused on the subjective and autonomous harmony. This theory based on complementary idea is applied to psychological attitude of architects on Spatial Expression in this study. Refuge, Prospect, Flow and Void are assumed as equivalent spatial elements to the four major emotional conditions suggested by $M.L\ddot{u}scher$. The couple combinations among them also characterize the architectural characters definitely and it is expected to be the reasonable criteria in analysing aesthetic value and motive of creating human space.

• Microbiology and Biotechnology Letters
• /
• v.25 no.3
• /
• pp.305-310
• /
• 1997

For the continuous production of transglucosylated steviosides, cyclodextrin glucanotransferase from Bacillus macerans was immobilized onto Diaion HPA 75 (styrene-divinylbenzene resin) that was screened from ion exchange resins, synthetic adsorbents and chitosan derivatives. The parameters influencing enzyme immobilization were examined in order to maximize the activity of immobilized enzyme. The optimum conditions for immobilization turned out to be: contact time 2 hr at 30$circ$C, pH 6$sim$9, and enzyme loading 20mg protein/g resin at 4.4 Os/Kg as osmolarity. Competing with other molecules having low molecular weight, enzyme was immobilized reversibly. The activity of immobilized enzyme was as high as 180U/g resin when the diafiltrated solution of stock enzyme was used. The optimum conditions for transglucosylation were as follows: pH 6.0, temperature 50$circ$C, 30% substrate solution composed of 15% stevioside mixture and 15% dextrin of which value of dextrose equivalent was about 9.0.

• Korean Journal of Soil Science and Fertilizer
• /
• v.33 no.1
• /
• pp.15-23
• /
• 2000

RC oscillation method was applied to study the condenser characteristics of two metal sticks insulated by vinyl tube and used in the dielectric constant determinations of most soils. Its capacitance as influenced by the contacted ambient materials was measured as relative capacitance of the sensor sticks compared with the standard one on the RC oscillation circuit. According to the equivalent circuit of the sensor stick set, the measured capacitance was composed of a basic capacitance connected in parallel with sensor stick capacitance, which was composed of lineally connected vinyl tube capacitances and the sensing part capacitance. The dielectric constant (U) of the contacted ambient moist soil located in the sensing part around the sticks interrelated with the other parameters as following equation. $$\frac{1}{C-B}=\frac{k}{U}+Z$$ where C is the output total relative capacitance, B is the hidden and fixed basic relative capacitance, k is a constant related with U, and Z is a constant for the insulating vinyl tube capacitances determined by its thickness and dielectric constant. The constant k is determined by the spacing and length of sensor sticks. The Z value is theoretically an invariable constant, but it may become considerably bigger than the determined in lab if air tube is formed on the surface of sensor sticks by some shocks on them after their installation in soil. Due to the unstability of lab Z value, it may be better to revise it after sensor stick's installation in soil and no shaking shocks should be applied on them.