• Korean Journal of Digital Imaging in Medicine
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• v.15 no.2
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• pp.63-68
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• 2013

Purpose : The relaxation times of tissue in MRI depend on strength of magnetic field, morphology of nuclear, viscosity, size of molecules and temperature. This study intended to analyze quantitatively that materials' temperatures have effects on T1 and T2 relaxation times without changing of other conditions. Materials and Methods : The equipment was used MAGNETOM SKYRA of 3.0T(SIEMENS, Erlagen, Germany), 32 channel spine coil and Gd-DTPA water concentration phantom. To find out T1 relaxation time, Inversion Recovery Spin Echo sequences were used at 50, 400, 1100, 2500 ms of TI. To find out T2 relaxation time, Multi Echo Spin Echo sequences were used at 30, 60, 90, 120, 150, 180, 210, 240, 270 ms of TE. This experiment was scanned with 5 steps from 25 to $45^{\circ}C$. next, using MRmap(Messroghli, BMC Medical Imaging, 2012) T1 and T2 relaxation times were mapped. on the Piview STAR v5.0(Infinitt, Seoul, Korea) 5 steps were measured as the same ROI, and then mean values were calculated. Correlation between the temperatures and relaxation times were analyzed by SPSS(version 17.0, Chicago, IL, USA). Results : According to increase of temperatures, T1 relaxation times were $214.39{\pm}0.25$, $236.02{\pm}0.87$, $267.47{\pm}0.48$, $299.44{\pm}0.64$, $330.19{\pm}1.72$ ms. T2 relaxation times were $180.17{\pm}0.27$, $197.17{\pm}0.44$, $217.92{\pm}0.39$, $239.89{\pm}0.53$, $257.40{\pm}1.77$ ms. With the correlation analysis, the correlation coefficients of T1 and T2 relaxation times were statistically significant at 0.998 and 0.999 (p< 0.05). Conclusion : T1 and T2 relaxation times are increased as temperature of tissue goes up. In conclusion, we suggest to recognize errors of relaxation time caused local temperature's differences, and consider external factors as well in the quantitative analysis of relaxation time or clinical tests.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.32-39
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• 2012

In this paper, the implementation of location based services (LBS) using S-DMB (satellite-digital multimedia broadcasting) system was proposed. In S-DMB System, the frequency of transmitted signal is about 2 GHz which has a characteristics of strong straightness but weak diffraction so that there are many shade areas such as indoors and underground spaces. Therefore the signal transmitted from the satellite should be retransmitted by the earth repeaters called as gap filler. Because each gap filler has its own identification value, the gap filler ID introduces the area in which the gap filler was installed. Generally, the 51st data symbols of S-DMB pilot signal transmitted from the satellite are padded by dummy value and gap filler ID is embedded in this pilot symbol by the gap filler when S-DMB signals are retransmitted by gap fillers. So using gap filler ID of S-DMB system, LBS such as region registration, distance and time to destination, alarm of local area information could be implemented. In the experiment to prove the performance of the proposed LBS system using the gap filler ID of the S-DMB system, the firmware of S-DMB chip composing of RF and baseband parts was lightly modified so that application processor was able to manipulate the gap filler ID and the its related regional information.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.369-381
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• 2011

Ginseng in Korea has not only the big production value but also till a good reputation from overseas in the name of 'Korea Ginseng'. Having spread rapidly nationwide from 2000 year, its production keeps on increasing but its consumption becomes lazy and its price is also falling down because of comsumer's concern about mainly overusing pesticide for ginseng. In order to cope with this problem, the government introduced the GAP certification system to ginseng in 2006 to reflect consumer's needs for food safety. This system will be a good opportunity to promote ginseng consumption dramatically. In this aspect it is very important to know how well this system is established and how ginseng farmers build marketing strategies to draw new wind in the market. This study was carried out to look over the GAP certified ginseng system and show its marketing strategies using 4P's(product, place, promotion and price). The main results are as follows. GAP ginseng system currently has some weaknesses such as lack of systematic certification management and after-service, nonrealistic certification fee and poor linkage from production to consumption. In the marketing mix strategies, product strategy suggests that the most desirable appearance be transplanted ginseng filled with branch roots and 4 to 5 year-ginseng, and it is necessary to choose multi-brand strategy divided for present into for self-sufficiency and family brand strategy by use if its brand enlarges to processed products in the future. In the place strategy, 3 stages like 'producer group' - 'GAP certified facility' - 'sales shop' are based as the physical marketing channel according to traceability, and connected with giant retail market and environment friendly stand, and if its sales volume enlarges, it should be considered the GAP ginseng specialized marketplace which is a type of chain store. In the promotion strategy, the promotion of government level is necessary at first and producer alliances require the promotion targeting at the group of women under 40 with differentiation from price, quality, and safety. In the price strategy, the early stage-high price strategy which sets 20~25% higher for self-sufficiency and 30~35% for present is desirable.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.1-11
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• 2015

WBAN(Wireless Body Area Network) operating around the human body aims at medical and non-medical service at the same time. and it is the short-range communication technology requiring low-power, various data rate and high reliability. Various studies is performing for IEEE 802.15.4, because IEEE 802.15.4 can provide high compatibility for operate WBAN among communication standard satisfiable these requirements. Meanwhile, in the case of coexisting many IEEE 802.15.4-based WBAN, signal interference and collision are the main cause that is decreasing data reliability. but IEEE 802.15.4 Standard does not consider about coexistence of many networks. so it needs improvement. In this paper, To solve about this problem, identify coexistence problem of IEEE 802.15.4-based WBAN by preliminary experiments. and propose a scheme to mitigate the reliability decrease at multiple coexistence WBAN. The proposed scheme can be classified in two steps. The first step is avoidance to collision on the CFP through improving data transmission. The second step is mitigation collision through converting channel access method. Proposed scheme is verified the performance by performing comparison experiment with Standard-based WBAN.

• Journal of the Korea Convergence Society
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• v.7 no.1
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• pp.89-95
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• 2016

The purpose of this experiment intend to evaluate the quality of the image based on the orbit and basal ganglia with high radiosensitivity for the noise, SNR and dose using the five kinds patient fixing pad in brain phantom MDCT(BrillianceTM CT 64 slice, PHILIPS, Netherward). The noise had a higher values in AP than those of others, but the SNR was lower in AP than those of others. The SNR was higher in UP than those of RP, PP, SP and AP. The UP, RP and PP were no statistically significant(p>0.05), whereas it was significant difference between UP, RP, PP and SP, AP(p<0.05). This is causes of the noise difference is generated due to the differences in the radiation absorption dose in accordance with each the component of the absorbed dose level of the detector according to the reference line and each of SOML when the radiation exposured. The CTDIvol(mGy) and DLP of orbit and basal ganglia were 56.95, 911.50, respectively. There is no difference between both mean dose. In conclusion, it is possible to distinguish among a kind of 5 patient fixing pad by using brain phantom MDCT. Overall, patient fixing pad of UP, RP and PP based on a brain phantom MDCT can provide useful information.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.2
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• pp.83-89
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• 2010

In this study, we studied whether hydrogen sulfide ($H_2S$) has an effect on the pacemaker activity of interstitial cells of Cajal (ICC), in the small intestine of mice. The actions of $H_2S$ on pacemaker activity were investigated using whole-cell patch-clamp technique, intracellular $Ca^{2+}$ analysis at $30^{\circ}C$ and RT-PCR in cultured mouse intestinal ICC. Exogenously applied sodium hydrogen sulfide (NaHS), a donor of hydrogen sulfide, caused a slight tonic inward current on pacemaker activity in ICC at low concentrations (50 and $100{\mu}m$), but at high concentration ($500{\mu}m$ and 1 mM) it seemed to cause light tonic inward currents and then inhibited pacemaker amplitude and pacemaker frequency, and also an increase in the resting currents in the outward direction. Glibenclamide or other potassium channel blockers (TEA, $BaCl_2$, apamin or 4-aminopydirine) did not have an effect on NaHS-induced action in ICC. The exogenous application of carbonilcyanide p-triflouromethoxyphenylhydrazone (FCCP) and thapsigargin also inhibited the pacemaker activity of ICC as NaHS. Also, we found NaHS inhibited the spontaneous intracellular $Ca^{2+}$ ($[Ca^{2+}]_i$) oscillations in cultured ICC. In doing an RT-PCR experiment, we found that ICC enriched population lacked mRNA for both CSE and CBS, but was prominently detected in unsorted muscle. In conclusion, $H_2S$ inhibited the pacemaker activity of ICC by modulating intracellular $Ca^{2+}$. These results can serve as evidence of the physiological action of $H_2S$ as acting on the ICC in gastrointestinal (GI) motility.

• The Korean Journal of Pharmacology
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• v.26 no.2
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• pp.127-133
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• 1990

Dibutyryl-cyclic AMP (db-cAMP) and forskolin were used to investigate vasodilating mechanism of cAMP in rabbit aorta. Db-cAMP and forskolin inhibited the development of contractile tension induced by norepinephrine (NE) concentration-dependently. However, high $K{^+}-induced$ contractile tension was inhibited less effectively by db-cAMP and forskolin. Db-cAMP and forskolin inhibited $^{45}Ca^{2+}$ uptake increased by NE. Forskolin seemed to inhibit $^{45}Ca^{2+}$ uptake increased by high $K{^+}$, but this inhibition was not significant statistically. Db-cAMP inhibited $Ca^{2+}-transient$ contraction by NE in $Ca^{2+}-free$ solution. In conclusion, it seems that cAMP blocks $Ca^{2+}$ influx through receptor operated $Ca^{2+}$ channels (ROCs), but that the effect of cAMP on $Ca^{2+}$ influx through voltage gated $Ca^{2+}$ channels (VGCs) is not clear in this experiment. Furthermore, cAMP is likely to inhibit calcium release from the intracellular stores.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.507-520
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• 2003

A V-shaped riffle is an artificial hydraulic structure haying two wings from the streamside with a narrow opening in between. It is usually made of crushed stones or large boulders. It limits channel width and accelerates the flow through the constricted section causing a local scour just downstream. The V-shaped riffle provides with a unique aquatic habitat by forming a pool and sandbars around the pool edge, increasing local morphologic, hydraulic and sedimentological diversity. This study investigates experimentally the scour characteristics of the V-shaped riffle in the sandbed stream and proposes a predictive equation for the scour. Total 45 cases of experiments were conducted to examine the effect of hydraulic factors and configuration of V-shaped riffle on the geometry of scour holes. From the comparison of the experimental results of this study with the predictive equation of spur dike by Breusers and Raudkivi(1991), it is found that their predictive equation of spur dike underestimates the maximum scour depth downstream of the V-shaped riffle. h new predictive equation for the maximum scour depth was developed using the non-dimensional hydraulic and geometrical variables. The parameters used in the proposed equations were determined using the experimental data. The analysis reveals that the scour depth is dependent dominantly on the Froude number at the opening of the V-shaped riffle, while the angle of riffle and the opening width also affect the scour depth. The proposed equation for the scour of V-shaped riffle well agrees with the experimental data. It can be used for estimating the scour of the V-shaped riffle in sandbed streams.

• Journal of the Korean Geographical Society
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• v.43 no.6
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• pp.808-823
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• 2008

Sediment abrasion in rivers is caused by the interaction between bedrock channel bed and sediment particles transported through the river. Abrasion rate of sediment particles in rivers is controlled by two major factors; Sediment transport conditions including hydraulic conditions form the erosive forces and physical and chemical strengths of the particles form a resistance force against abrasion and other erosional processes. Physical experiments were performed to find the role of each variable on sediment abrasion process. Total 266 sediment particles were used in this experiment. All sediment particles were divided into 11 independent sediment groups with sediment particle size and sediment loads. Each sediment groups were abraded in tumbling mill for up to 8 hours. Changes in weight were recorded by run and total: 2,128 cases of abrasion rate were recoded. Physical strength of rock particles was measured with point load strength index. It is found that sediment abrasion rate has a negative functional relationship point load strength index ($I_{a(50)}$) ($R^2=0.22$). It was suggested that physical strength of sediment particles set the "maximum possible abrasion rate'. As sediment flux increases, abrasion rates of sediment particles with similar point load strength index were changed. It could be concluded that not only physical characteristics of sediment particles, but also sediment transport conditions control sediment abrasion rates.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.45-51
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• 2001

In order to investigate the optimal design weight of sinkers for preventing cage net from deforming in current, the model experiment on 2 types of square cage nets with different S sub(n)/S, the ratio of total area of netting projected to the perpendicular to the water flow S sub(n) to wall area of netting S, and 4 kinds of sinkers was carried out in circulation water channel. The model cage nets were made in 1/10 scale and the total weight in water of 4 sinkers attached to each corner of their bottom frames was 18, 54, 90, and 126g, respectively equivalent to 0.1, 0.3, 0.5, and 0.7 kg per unit area of prototype net. The results obtained can be summarizes as follows; Due to the deformation of each net where it was lifted towards the surface in severe conditions, its volume was reduced. This depended highly on the weight of sinkers placed in the bottom corner of cage nets, even if the variation of S sub(n)/S had a little effect on their deformation in current less than 0.4 m/s. In addition, it was observed that the total weight of sinkers for preventing the net from deforming to the extent of less than 50% inside its initial volume was 31 to 245 kg in the range of 0.3 to 0.6 m/s and the adequate design weight of sinker was approximately 0.5 kg per its unit area.