• Journal of Korean Port Research
• /
• v.13 no.1
• /
• pp.155-166
• /
• 1999

The construction of the coastal structures and reclamation work causes the circulation reduced in the semi-closed inner water area and the unbalanced sediment budget of beach results in an alteration of beach topography. Among the various fluid motions in the nearshore zone water particle motion due to wave and wave-induced currents are the most responsible for sediment movement. Therefore it is needed to predict the effect of the environmental change because of development and so the prediction of wave transformation dose. The purpose of this study is to introduce the relation between waves wave-induced currents and sediment movement. In this study we will show numerical method using energy conservation equation involving reflection diffraction and reflection and the surfzone energy dissipation term due to wave breaking is included in the basic equation. For the wave-induced current the momentum equation was combined with radiation stresses lateral mixing and friction Various information is required in the prediction of wave-induced current depending on the prediction tool. We can predict changes in wave-induced current from the distribution of wave especially near the wave breaking zone. To evaluate these quantities we have to know the local condition of waves mean sea level and so on. The results from the wave field and wave-induced current field deformation models are used as input data of the sediment transport and bottom change model. Numerical model were established by a finite difference method then were applied to the development plan of the eastern Pusan coastal zone Yeonhwa-ri and Daebyun fishing port. We represented the result with 2-D graphics and made comparison between before and after development.

• Progress in Medical Physics
• /
• v.25 no.3
• /
• pp.151-156
• /
• 2014

The purpose of this study was to confirm the feasibility of imaging of therapy region from the boron neutron capture therapy (BNCT) using the measurement of the prompt gamma ray depending on the neutron flux. Through the Monte Carlo simulation, we performed the verification of physical phenomena from the BNCT; (1) the effects of neutron according to the existence of boron uptake region (BUR), (2) the internal and external measurement of prompt gamma ray dose, (3) the energy spectrum by the prompt gamma ray. All simulation results were deducted using the Monte Carlo n-particle extended (MCNPX, Ver.2.6.0, Los Alamos National Laboratory, Los Alamos, NM, USA) simulation tool. The virtual water phantom, thermal neutron source, and BURs were simulated using the MCNPX. The energy of the thermal neutron source was defined as below 1 eV with 2,000,000 n/sec flux. The prompt gamma ray was measured with the direction of beam path in the water phantom. The detector material was defined as the lutetium-yttrium oxyorthosilicate (Lu0,6Y1,4Si0,5:Ce; LYSO) scintillator with lead shielding for the collimation. The BUR's height was 5 cm with the 28 frames (bin: 0.18 cm) for the dose calculation. The neutron flux was decreased dramatically at the shallow region of BUR. In addition, the dose of prompt gamma ray was confirmed at the 9 cm depth from water surface, which is the start point of the BUR. In the energy spectrum, the prompt gamma ray peak of the 478 keV was appeared clearly with full width at half maximum (FWHM) of the 41 keV (energy resolution: 8.5%). In conclusion, the therapy region can be monitored by the gamma camera and single photon emission computed tomography (SPECT) using the measurement of the prompt gamma ray during the BNCT.

• Progress in Medical Physics
• /
• v.9 no.2
• /
• pp.77-88
• /
• 1998

Wedge shaped isodoses are desired in a number of clinical situations. Hard wedge filters have provided nominal angled isodoses with dosimetric consequences of beam hardening, increased peripheral dosing, nonidealized gradients at deep depths along with the practical consequendes of filter handling and placement problems. Dynamic wedging uses a combination of a moving collimator and changing monitor dose to achieve angled isodoses. The segmented treatment tables(STT) that monitor unit setting by every distance of moving collimator, was induced by numerical formular. The characteristics of dynamic wedge by STT compared with real dosimetry. Methods and Materials : The accelerator CLINAC 2100C/D at Yonsei Cancer Center has two photon energies (6MV and 10MV), currently with dynamic wedge angles of 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$ and 60$^{\circ}$. The segmented treatment tables(STT) that drive the collimator in concert with a changing monitor unit are unique for field sizes ranging from 4.0cm to 20.0cm in 0.5cm steps. Transmission wedge factors were measured for each STT with an standard ion chamber. Isodose profiles, isodose curves, percentage depth dose for dynamic wedge filters were measured with film dosimetry. Dynamic wedge angle by STT was well coincident with film dosimetry. Percent depth doses were found to be closer to open field but more shallow than hard wedge filter. The wedge transmission factor were decreased by increased the wedge angle and more higher than hard wedge filters. Dynamic wedging probided more consistent gradients across the field compared with hard wedge filters. Dynamic wedging has practical and dosimetric advantages over hard filters for rapid setup and keeping from table collisions. Dynamic wedge filters are positive replacement for hard filters and introduction of dynamic conformal radiotherapy and intensity modulation radiotherapy in a future.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.1
• /
• pp.135-147
• /
• 2013

Most of slope failures are triggered by heavy rainfall during rainy season. If the rain keeps on for the season, the water content of the ground increases and its matric suction decrease, and then the safety factor of soil slope gets lower. The change of water table level for soil slope stability dose not describe the behavior of the soil slope in real situation, hence it may be necessary to modify the design standard for slope stability in association with rain infiltration. For correct design, economical construction, and maintenance of a soil slope, unsaturated flow analysis is needed for estimation of slope instability regarding water infiltration and soil behavior on unsaturated soil slopes. The entire soil slope cannot be saturated by prolonged rainfall and wetting band depth (saturated zone) just deepens from slope surface, hence the cause of the shallow surface slide is the wetting band depth depending on rainfall duration and intensity. Therefore, the paper presents the differences between theoretical equation and numerical analysis for wetting band depth on soil surface and its safety factor, and compares the slope stability obtained from unsaturated flow analysis with that obtained from conventional slope stability analysis.

• Sleep Medicine and Psychophysiology
• /
• v.17 no.2
• /
• pp.85-90
• /
• 2010

Objectives: Ginseng has a long history of being used in insomnia treatment and there is some evidence from animal studies of its sleep-enhancing property. From this, it can be assumed that ginseng has sleep-promoting effect in humans. The purpose of this study was to investigate the effect of Korean red ginseng on change of sleep architecture in humans. Methods: A total of 20 healthy young males with regular sleep and wake habits and without any psychiatric nor cognitive problems were selected based on review of sleep questionnaires and sleep diaries they completed followed by an interview with a board-certified psychiatrist. The subjects were randomly assigned to red ginseng or placebo for 2 weeks of trial. The total daily dose of ginseng was 4,500 mg. The polysomnographic recordings were made at baseline and at 2 weeks after. The effects of red ginseng and placebo on sleep were assessed by comparing the changes in polysomnographic variables between the two groups. Results: A total of 15 subjects, 8 from red ginseng group and 7 from placebo group, were included to undergo polysomnographic procedures. The red ginseng group showed tendencies to increase stage 3 sleep (p=0.087) and to decrease stage 2 sleep (p=0.071) from the baseline compared with the placebo group. Conclusion: Korean red ginseng tends to increase deep sleep and decrease shallow sleep. Our result is in line, at least in part, with previous findings that Korean red ginseng increased total and NREM sleep in rats. Further studies with higher ginseng dosage, larger sample size and longer trial duration should be conducted to confirm the sleep stabilizing and balancing effects of Korean red ginseng.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.1
• /
• pp.1-7
• /
• 2001

Total upland area for cultivating the vegetable crops in the Alpine soils of Northeastern South Korea has been extending its limit to meet the increasing demand of vegetable food in recent decades. About 70% of these alpine soils are located in over 7% of the slope and most of vegetable crops have been cultivated intensively without practicing the best management systems. Thus, soil erosion and continuous cropping system have degenerated the soil fertility and shown detrimental effects on water quality. We initiated an intensive and extensive investigation to characterize the fertility problems encountered in these uplands. Objectives of this paper were to characterize the fertility status in the Alpine soils cultivated with vegetable crops for many years and to provide the recommendations for adequate soil management measures including fertilization and erosion control. Soils in general have good drainage with textural classes of loam or sandy loam. Their topographical characteristics tended to lead them to shallow plow layers, and the steepness of the terrain created erosion hazard. Of the soils examined, about 11% of uplands over 30% gradient was found in need of an urgent reforestation. A high content of gravel and firm hardness of soil attributed to inhibit the utilization of farm machinery and plant-root development. The average soil pH 5.6 was slightly low relative to pH 5.70 of the national average. Organic matter content was high compared with 2.0% of national average, but decreased with the prolonged cultivation periods. Available $P_2O_5$ concentration was unusually high due to the consequence of over dose application with chemical and organic fertilizers. Exchangeable cations as Ca, Mg, and K were appeared to be decreased in these regions with prolonging the cultivation periods. There were no significant differences in cation exchange capacity (CEC) and electrical conductivity (EC) among locations. Heavy metal contents were mostly lower than the threshold of danger level designated by Soil Environment Conservation Law of South Korea. Results indicated that a proper countermeasure and the best management practice should be immediately implemented to conserve the top soil and fertility in the Alpine regions.