• Nuclear Engineering and Technology
• /
• v.54 no.4
• /
• pp.1421-1430
• /
• 2022

The computation of the solid angle and the detector efficiency is considering to be one of the most important factors during the measuring process for the radioactivity, especially the cylindrical γ-ray NaI(Tl) detectors nowadays have applications in several fields such as industry, hazardous for health, the gamma-ray radiation detectors grow to be the main essential instruments in radiation protection sector. In the present work, a generic numerical simulation method (NSM) for calculating the efficiency of the γ-ray spectrometry setup is established. The formulas are suitable for any type of source-to-detector shape and can be valuable to determine the full-energy peak and the total efficiencies and P/T ratio of cylindrical γ-ray NaI(Tl) detector setup concerning the truncated conical radioactive source. This methodology is based on estimate the path length of γ-ray radiation inside the detector active medium, inside the source itself, and the self-attenuation correction factors, which typically use to correct the sample attenuation of the original geometry source. The calculations can be completed in general by using extra reasonable and complicate analytical and numerical techniques than the standard models; especially the effective solid angle, and the detector efficiency have to be calculated in case of the truncated conical radioactive source studied condition. Moreover, the (NSM) can be used for the straight calculations of the γ-ray detector efficiency after the computation of improvement that need in the case of γ-γ coincidence summing (CS). The (NSM) confirmation of the development created by the efficiency transfer method has been achieved by comparing the results of the measuring truncated conical radioactive source with certified nuclide activities with the γ-ray NaI(Tl) detector, and a good agreement was obtained after corrections of (CS). The methodology can be unlimited to find the theoretical efficiencies and modifications equivalent to any geometry by essential sufficiently the physical selective considered situation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.05a
• /
• pp.254-260
• /
• 1999

Meteor Burst Communication can provide effective and economical means of communication where long distance VHF NLOS data transmission is needed; often ranges more than 1000 km. It has been, however, so far considered unsuitable for short distance application because of phenomenal decrease in burst durations, which leads to decreation of total duty rate of the system. This paper extensively analyzes characteristics of shot distance MB(Meteor Burst) path and shows the low duty rate may be improved by increasing burst rate through adapting antenna beam width to cover entire hot-spot region in the space and, by compensating effective burst length through cutting down man-made noises introduced by antenna. Based on the analysis, we are developed a small-opening-cavity antenna, especially designed for short distance MB path. In operation, the antenna is to be buried under ground surface so as to improve directivity and reduces noise introduction. The antenna exhibits power gain of 3 dB with 90 degree beam width and thus enables to illuminate entire hot-spot regions with the elevation angle of 8-90 degree which is the case of transmission less than 100 km. Directivity horizontal to earth surface is suppressed to minimum which enables to cut man-made noises from near-by sources down to more than 3 dB from the level reported with conventional 4 element Yagi. A series of experiments performed on 100 km MB paths have conformed that, with the antenna installed at receiving site, the burst rate and duration time have been noticed to increase by 10 and 20 percent respectively from the values obtained by conventional 4-element Yagi antenna under same testing condition.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.7 no.2
• /
• pp.16-28
• /
• 2004

A seam-line determination algorithm is proposed to determine image border-line in mosaicing using the transformation of gray value differences and dynamic programming. Since visually good border-line is the one along which pixel differences are as small as possible, it can be determined in association with an optimal path finding algorithm. A well-known effective optimal path finding algorithm is the Dynamic Programming (DP). Direct application of the dynamic programming to the seam-line determination causes the distance effect, in which seam-line is affected by its length as well as the gray value difference. In this paper, an adaptive cost transform algorithm with which the distance effect is suppressed is proposed in order to utilize the dynamic programming on the transformed pixel difference space. Also, a figure of merit which is the summation of fixed number of the biggest pixel difference on the seam-line (SFBPD) is suggested as an evaluation measure of seamlines. The performance of the proposed algorithm has been tested in both quantitively and visually on various kinds of images.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.4
• /
• pp.318-327
• /
• 2017

It is essential for the near-field receiving measurement to make beam pattern and check the performance of a active phased array antenna system. Also, we could obtain compensation value for mono-pulse function through the near-field receive test, however, if the radar has many frequency channel, the test would take long time and hard effort. So it is needed that frequency channels are selected for measurement and calculates the values for other frequency channels to improve efficiency in development and manufacture. In this case, the phase variations in sum and del channels would be checked. The phase measurement includes un-linear characteristic because of wrapping effect. Generally, radars have similar path length in sum and del channel, but if a radar has a electrical length gap between sum and del channel, errors could occur by phase's wrapping effect. In this paper, the interpolation method's error caused by electrical length gap is checked and the effective method for frequency channel selection to avoid wrapping effect is introduced.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.150.1-150.1
• /
• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.5 no.3
• /
• pp.99-106
• /
• 2002

The application method of GIS for planning of forest road network can be save the efforts and cost by frequently change of forest road and evaluation the forest road route before construction. The purpose of this study is to suggest the proper method for planning an optimal forest road network in mountains forest using geographic information system(GIS) in the national forest of Mt. Kumsan at Namhae-gun, Gyungsangnam-do. In the forest road network planning by the minimum longitudinal gradient, The total length was 20.41km, and road density was 6.92m/ha. In the forest road network planning by mixed with the minimum longitudinal gradient and the maximization of investment effect, The total length was 21.15km, and road density was higher than that of the minimum longitudinal gradient as 7.17m/ha. The road length overlapped by cost path was more short than 3.52m/ha of the minimum longitudinal gradient as 1.73km. So, it appeared that forest road has an high effectiveness in yarding function. Therefore, it considered that the geographic information system could provide an effective and resonable solutions for planning of optimal forest road network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.2 s.105
• /
• pp.178-183
• /
• 2006

The proposed triple-band compact chip antenna using coupled meander line and stacked meander structure for mobile RFID/PCS/WiBro. The proposed antenna is designed to operate at 900, 1,800, and 2,350 MHz, and is realized by parasitic coupled and stacked a meander line. Meander lines are using extend length of effective current path more than monopole and contribute miniaturization. The coupled meander line controls the excitations of the mobile RFID and PCS, stacked meander line controls the excitation of the WiBro. The fabricated antenna size is $10.98{\times}22.3{\times}0.98\;mm$. The resonance frequencies are 905 MHz, 1.77 GHz and 2.32 GHz. The impedance bandwidths are 24 MHz, 140 MHz and 92 MHz. The maximum gains of antenna are 0.34 dBi, 2.58 dBi and 0.4 dBi at resonance frequencies.

• The Journal of Korean Physical Therapy
• /
• v.22 no.5
• /
• pp.25-31
• /
• 2010

Purpose: The purpose of this study is to provide an efficient and scientific basis for muscle activity (%MVIC) of RA, EO, VL, HS muscles and balance in soccer players through dynamic lumbar stability exercise and static lumbar stability exercise. Methods: This study included 23 soccer players belonging to D University of J province who attended the program for 30 minutes at a time and three times a week for 4 weeks. Of these 13 attended the dynamic lumbar stability exercise (DLSE) program and 10 the static lumbar stability exercise (SLSE) program. The differences between the effects of the dynamic lumbar stability exercise program and static lumbar stability exercise program were analyzed. Results: To increase muscle activity (%MVIC) and balance (WPL), the dynamic lumbar stability exercise program was more effective than was the static lumbar stability exercise program. 1) The %MVIC of trunk muscle (RA &EO) and lower extremitys muscle (VL & HS) increased from before training to after training in the case of the participants who performed the dynamic lumbar stability exercise. 2) The whole path length (WPL) decreased from before the training to after the training. The 2 groups significantly differed in this regard. Conclusion: Dynamic lumbar stability exercise program helps to improve the balancing ability and muscle activity in a soccer players who requires both muscle activity and balance than does any other players.

• Journal of IKEEE
• /
• v.20 no.4
• /
• pp.361-366
• /
• 2016

This paper presents the ESD protection circuit with improved electrical characteristic and area efficiency. The proposed ESD protection circuit has higher holding voltage and lower trigger voltage characteristics than the 3-Stacking LVTSCR. In addition, it has only two stages and has improved Ron characteristics due to short discharge path of ESD current. We analyzed the electrical characteristics of the proposed ESD protection circuit by TCAD simulator. The proposed ESD protection circuit has a small area of about 35% compared with 3-Stacking LVTSCR, The proposed circuit is designed to have improved latch-up immunity by setting the effective base length of two NPN parasitic bipolar transistors as a variable.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.4
• /
• pp.163-174
• /
• 2020

PURPOSE: This study examined the effects of Robot Tilt-table Training (RTT) on the lower extremity strength, balance, gait, and satisfaction with rehabilitation, in patients with subacute stroke (less than six months after stroke onset), and requiring intensive rehabilitation. METHODS: A total of 29 subacute stroke patients were divided into an RTT group (n = 14) and a Body Weight Support Treadmill Training (BWSTT) group (n = 15). The mean age of patients was 62 years. RTT and BWSTT were performed for four weeks, three times a week, for 30 minutes. Isometric strength of the lower extremities before and after intervention was compared by measuring the maximal voluntary isometric contraction of the lower extremity muscles. To compare the balance function, the center of pressure (COP) path-length and COP velocity were measured. Timed Up & Go test (TUG) and 10 Meter Walking Test (10 MWT) were evaluated to compare the gait function. A satisfaction with rehabilitation survey was conducted for subjective evaluation of the subject's satisfaction with the rehabilitation training imparted. RESULTS: In the intra-group comparison, both groups showed significant improvement in lower extremity strength, balance, gait, and satisfaction with rehabilitation, by comparing the parameters before and after the intervention (p < .05). Comparison of the amount of change between groups revealed significant improvement for all parameters in the RTT group, except for the 10 MWT (p < .05). CONCLUSION: Both groups are effective for all variables, but the RTT group showed enhanced efficacy for variables such as lower extremity strength, balance, gait, and satisfaction with rehabilitation, as compared to the BWSTT group.