• Journal of the Korean Society of Radiology
• /
• v.8 no.7
• /
• pp.383-387
• /
• 2014

In this paper, for a new detection system development with the better accurate dose evaluation and beam distribution imaging using the small field irradiation of linear accelerator, the compound semiconductor based detection sensors were fabricated and the performance evaluation was investigated. The special particle-in-binder sedimentation was used for a large area film sensor fabrication. The detection properties for high energy x-rays were investigated from a dark current, an output current, a rising time, a falling time, and response delay measurement. The experimental results, the $TiO_2$ mixed $HgI_2$ sensor showed the best electrical characteristics than $PbI_2$, PbO, pure $HgI_2$. Linearity, repeatability, and accuracy tests from LINAC were tested, the $TiO_2$ mixed $HgI_2$ sensor showed the better performance than the commercially available dosimetry devices.

• Journal of Yeungnam Medical Science
• /
• v.24 no.2
• /
• pp.232-242
• /
• 2007

Background : The safety and efficacy of trabeculectomy with Mitomycin C (MMC) for surgical treatment in aphakic and pseudophaic eyes were retrospectively evaluated. Materials and Methods : The authors reviewed 51 eyes of 45 patients who had been followed up for at least 6 months after trabeculectomy using MMC for aphakic and pseudophakic eyes. The success rate and complications were analyzed. The success criteria included intraocular pressures of 21 mmHg or less with or without glaucoma medications and no loss of light perception. Surgical failure was defined as a postoperative loss of light perception in patients with preoperative vision better than light perception, additional glaucoma surgery, or phthisis bulbi in patients with preoperative vision of no light perception. Results : The average follow up period was 27.7 months and the intraocular pressure was controlled under 21 mmHg in 36 eyes of 51 (70.6%) after the procedure with or without medication for glaucoma. Using the Kaplan-Meier survival analysis, the cumulative success rate at the 3-, 6-, 12-, 24- and 36-month intervals were 98.0%, 94.1%, 91.9%, 83.4% and 75.5%, respectively. The complications observed were hyphema (4 eyes), serous choroidal detachment (4 eyes), hypotony (3 eyes), and endophthalmitis (1 eye). Conclusion : Trabeculectomy using Mitomycin C for the treatment of aphakic and pseudophaic eyes was safe and effective.

• The Journal of Society for e-Business Studies
• /
• v.22 no.4
• /
• pp.159-173
• /
• 2017

In order to provide technical financial support to small and medium-sized venture companies based on technology, the government implemented the TCB evaluation, which is a kind of technology rating evaluation, from the Kibo and a qualified private TCB. In this paper, we briefly review the current state of TCB evaluation and available indicators related to technology evaluation accumulated in the Korea Credit Information Services (TDB), and then use indicators that have a significant effect on the technology rating score. Multiple regression techniques will be explored. And the relative importance and classification accuracy of the indicators were calculated by applying the key indicators as independent features applied to the generalized boosting model, which is a representative machine learning classifier, as the class influence and the fitness of each model. As a result of the analysis, it was analyzed that the relative importance between the two models was not significantly different. However, GBM model had more weight on the InnoBiz certification, R&D department, patent registration and venture confirmation indicators than regression model.

• Journal of the Mineralogical Society of Korea
• /
• v.14 no.2
• /
• pp.99-110
• /
• 2001

A gem-quality yttria-stabilized zirconium oxide crystals were synthesized by the skull-melting method, using the RF electrical apparatus. Principal raw materials used were $ZrO_2$and 25 wt.% $Y_2O_3$as stabilizer and 0.03~0.05 wt.% $Nd_2O_3$decolorizing agent were added to it. The single crystals were approximately 20$\times$63 mm in size with chemical composition $Zr_{0.73}$ $Y_{0.27}$ $O_{1.87}$ . The crystals are isotropic with no appreciable anisotropism under a polarizing microscope. Their refractive indices are in the range of 2.15~2.18, specific gravity 5.85, Mohs' hardness 8~8.5, and reflectivity 13.47%. The zirconia crystals were confirmed to have cubic structure with Face-centered lattice(Z=4), space group Fm3m ($CaF_2$-type structure) and unit cell parameters are a=5.157 $\AA$. The optimal growing conditions for yttria-stabilized zirconia are 50 kW, 2.94 MHz in power and to use a crucible with 105 mm $\times$ 135 mm in size. When the lowering speed of the crucible was set 16mm/hr gave the best yield, 42%. Since the refractive index(2.15~2.18) of cubic zirconia is smaller than that of diamond, the angle between crown and pavilion should be fashioned to make it smaller than $40.5^{\circ}$ to show the maximum brilliancy and fire.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.5
• /
• pp.368-377
• /
• 2011

A package type of SCR (selective catalytic reduction) system that was proposed for removing the $NO_x$ found in flue gas from the small scale of air pollution sources was evaluated. The efficiency of the SCR system is determined by the proper utilization of catalytic media installed inside of the system, and the proper distribution of flow velocity and $NH_3$ concentration in the flue gas is a crucial factor for using the catalytic media. In this study, the distributions of $NH_3$ concentration were estimated under the various arrays and shapes of AIG at the given gas flow condition. The value of RMS (%) in $NH_3$ concentration is 95.3% at co-current flow (at $0^{\circ}$) injection but it is 90.1% at the condition of counter-current flow (at $120^{\circ}$) condition, which implies the counter-current injection is more favorable. By rearranging the $NH_3$ injection flow rates based on the distribution of velocity and $NH_3$ distribution in basic calculation, the value of RMS (%) in $NH_3$ concentration was reduced to 62.8%. The enhanced effect of $NH_3$ mixing by the combined effect of arrays and shapes are complied in the study.

• Journal of the Korean Society for Railway
• /
• v.18 no.4
• /
• pp.309-316
• /
• 2015

The contribution of exterior devices such as bogie fairings and pantographs to running resistance was estimated on the basis of coasting tests at up to 350 km/h with the help of the Korean Next Generation High speed train (HEMU-430X). In order to assess the reduction of air resistance by nose car's bogie fairing, coasting tests were conducted with a removable bogie fairing at various speed ranges. And, the contribution of the pantograph to air resistance was also estimated with coasting tests that include the pantograph's rising and descent modes. The linear regression method was used to examine decelerations from time-velocity data and the equation of resistance to motion is proposed from the deceleration data. From the aerodynamic term of the equation of resistance to motion, the contribution to air resistance by nose car's bogie fairing and pantograph was estimated. The results show that the air resistance was reduced by about 3.8% by the nose car's bogie fairing. And, the 3.9% increase of air resistance by the pantograph (open knee mode) has been found.

• Korean Journal of Crystallography
• /
• v.9 no.1
• /
• pp.21-29
• /
• 1998

The rare-earth orthoborate family, RM3(BO3)4 is known to be the most promising material for the microlaser host. To grow LaSc3(BO3)4 single crystal, the phase relation of the system LaBO3-ScBO3 was investigated by DTA method. LaSc(BO3)4 was the unique intermediate compound in the binary system the peritectic reaction point of which was 1495 ±2℃. Owing to the peritectic behavior of the compound, the crystal growth of the rare-earth Sc-borate was carried out by pulling from the melt-soultion of La1+xSc3-x(BO3)4. The optimal conditions for the growth of LaSc3(BO3)4 were determined by traditional CZ method : pulling speed 0.7mm/hr, rotation speed 7-10 rpm under reduction condition. Pt and Ir crucibles could be used for about 8-10 times of growth. The effect of thermal configurations on the temperature distribution was investigated. A special two-coordinate manipulator was made for the precise movement of thermocouples from the melt to the top of the furnace for several thermal configurations. The radial gradient on the melt surface depends strongly on the construction of the afterheater. On the other hand, the axial gradient was mainly propotional to both the opening degree of baffle plate and the mutual positions of crucible and heater.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2002.09a
• /
• pp.67-84
• /
• 2002

A shallow high-resolution seismic reflection survey was carried out at the Mineopo tidal flat on the western coast of Korea. The purpose of the survey was to investigate shallow sedimentary structure of the tidal (fat associated with the recent sea level change. A total of 795 shots were generated at 1 m interval from a 5-kg hammer source and recorded on 48 channels of 100 Hz geophones along two mutually perpendicular profiles. The water-saturated ground condition resulted in suppressed ground rolls by significantly decreasing rigidity. In addition, seismic velocities over 1500 m/s provided easy segregation of reflected arrivals from lower velocity noise. As a consequence, seismic sections were created that are high in resolution and signal to noise ratio as well. The stack sections show that the tidal flat consists of 5 sedimentary sequences above acoustic basement. Although deposition is largely characterized by the transgressive sedimentary facies resulting from sea level rise, erosional surfaces are well-resolved within the sequences.

• Journal of Navigation and Port Research
• /
• v.39 no.4
• /
• pp.285-291
• /
• 2015

Exposure to cold sea water can be life-threatening to the drowned individual. Although appropriate life jacket can be usually be provided for the buoyance at the drowning accident, heat loss can make the drowned individual experience the hypothermia. Inflatable life jackets filled with inflatable air pocket can increase the thermal protection as well as the buoyancy force. Because it is important to know how the human body behaves unde the different life jacket, present study compares the thermal insulation capacity of solid type life jacket with that of inflatable life jacket. In order to represent the insulation capacity of life jacket, thermal resistance is estimated based on the assumption of steady-state. Also, a transient three-dimensional thermal distribution of the thigh is analyzed by using finite element method implementing the Pennes bioheat equation. The finite element model is a segmental, multi-layered representation of the body section which considers the heat conduction within tissue, bone, fat and local blood flow rate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.28-34
• /
• 2020

A reservoir is defined as an artificial facility that stores and controls water during floods and droughts. Korea has constructed and managed reservoirs all over the country to benefit farming communities. The importance of reservoirs has decreased gradually due to urbanization and the spread of tap water, but the importance of water is increasing because of the recent shortage of water and the resulting rise in the price of water resources. Therefore, this study suggests countermeasures through an analysis of the used threshold for agricultural reservoirs. To this end, the forecast of rainfall up to 2100 was first analyzed using flood estimates and RCP scenarios through rainwater data collection. The increase in the RCP 8.5 scenario, the largest increase in the probability rainfall, was calculated by adding it to the current probability rainfall, and it was predicted that the marginal height of Odong Dam would reach its limit in 2028. Therefore, as a countermeasure against this, the measures to secure effective water storage were suggested through measures, such as lowering the height of Yeosu and installing movable beams. Overall, it is expected that effective management of the reservoirs used for agriculture will be possible in the future.