• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.3
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• pp.83-89
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• 2010

Scalable routing is one of the key challenges in designing and operating large scale MANETs. Performance of routing protocols proposed so far is only guaranteed under various limitation, i.e., dependent of the number of nodes in the network or needs the location information of destination node. Due to the dependency to the number of nodes in the network, as the number of nodes increases the performance of previous routing protocols degrade dramatically. We propose Cluster Overlay Dynamic Source Routing (CODSR) protocol. We conduct performance analysis by means of computer simulation under various conditions - diameter scaling and density scaling. Developed algorithm outperforms the DSR algorithm, e.g., more than 90% improvement as for the normalized routing load. Operation of CODSR is very simple and we show that the message and time complexity of CODSR is independent of the number of nodes in the network which makes CODSR highly scalable.

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.257-263
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• 2015

Acoustic identification of inner materials in a single-layer cylindrical shell is investigated with acoustic resonance theory. The theoretical resonance peak frequencies for a cylindrical shell are little affected by the density variation, but remarkably changed by the sound speed variation of inner materials. Such acoustic dependency can be utilized to identify inner materials in a cylindrical shell. Acoustic resonance spectrogram for a single-layer cylindrical shell is theoretically plotted as functions of normalized frequency and sound speed of inner materials. The inner materials can be acoustically identified by overlapping acoustic resonance peaks from measured backscattering sound field on the spectrogram. To experimentally confirm this method, backscattering sound field of cylindrical shell filled with water, oil or ethylene glycol was measured in water tank. The inner materials could be identified by acoustic resonance peaks of the backscattering sound field monostatically measured with a transduce of 1.05 MHz center frequency.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.111-117
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• 2008

The effect of characteristics of ground and circular foundation on the dynamic behavior of the foundation in vertical motion are considered using an approximated analytical solution and a finite element analysis with absorbing (consistent transmitting) boundary. The shear wave velocity of homogeneous ground affects the resonant frequency of the foundation much but has nothing to do with the maximum response amplitude at resonant frequency. The density in this case affects both the resonant frequency and the maximum response. The size and the mass of the circular foundation are related both to the resonant frequency and the maximum response. However, Poisson's ratio has very little effect on dynamic behavior of the foundation. When the ground is not homogeneous but has the layers, different formations of shear wave velocities would also change the maximum response at resonant frequency.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.4
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• pp.1075-1081
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• 2003

This experimental research has been done to study the effects of Palmul-tang on the anti-allergic reaction. We found the several important results from the research which has been performed by two experiments toward immediately type and delayed type in order to study the effects of Palmul-tang on hypersensitivity response to mice. The results obtained from our research are as following: The survival rate of one group to which we injected only the compound 48/80 is almost 0% according to its density and timing test. In the other hand. the survival rates of the other group to which we injected both of the compound 48/80 and Palmul-tang are 20%, 0%. 40%, 10%, 20% and 50% according to 0.025, 0.05, 0.1, 0.25 0.5 and 1 (mg/g) of compound 48/80. Time dependency test also shows the 30% and 20% survival rates in 5 and 10 minutes. Palmul-tang revealed the significantly inhibitory effect on Compound 48/80 induced Mast cell degranulation. Palmul-tang showed the significantly inhibitory effect in the delayed type hypersensitivity response to picry1 chloride. Palmul-tang showed the significantly inhibitory effect in the delayed type hypersensitivity response to sheep red blood cell. Our research provides the important evidence that Palmul-tang is benificial to the prevention and treatment of allergy related aiseases.

• The Journal of the Acoustical Society of Korea
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• v.33 no.1
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• pp.10-20
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• 2014

To study the water-entry impact noise, on-board experiment using a small launcher firing various objects was performed in the Yellow Sea. As the launcher fires a cylindrical object from the ship vertically, generated noise is measured with a hydrophone on the starboard of Chung-hae, Marine surveyor. Three types of cylindrical objects, which have noses of flat-faced, conical, and hemisphere, were used during the experiment. The measured noise exhibits a time-dependency which can be divided into three phases: (1) initial impact phase, (2) open cavity flow phase, (3) cavity collapse and bubble oscillation phase. In most cases, the waveform of bubble oscillation phase is dominant rather than that of initial impact phase. Pinch-off time, where a cavity begins to collapse, occurs at 0.18 ~ 0.2 second and the average lasting time of bubble was 0.9 ~ 1.3 second. The energy of water-entry impact noise is focused in the frequency region lower than 100 Hz, and the generated noise is influenced by the nose shapes, object mass, and launching velocity. As a result, energy spectral density on the bubble frequency is higher in the order of flat-faced, conical, hemisphere nose, and the increase of initial energy raises the energy spectral density on the bubble frequency in the cylinder body of same shape. Finally, we compare the measurements with the simulated signals and spectrum based on the bubble explosion physics, and obtain satisfactory agreements between them.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.1
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• pp.68-75
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• 1999

This study was conducted to examine the effects of Arbuscular Mycorrhizae inoculation and phosphorus application on early growth of hot pepper. Gigaspora margarita and Acaulospora spinosa were chosen for this investigation and inoculated into soils of different P levels by varying inoculation time and density. After treatment, some relevant growth responses of hot pepper were measured. Regardless of soil P levels, hot peppers treated with arbuscular mycorrhizal fungi had 5~34% more fresh weight than those untreated, but the effect of inoculation time and density was not different between two species. With decreased P levels, the infection rate and dependency of hot peppers increased. The content of P and K of AMF-inoculated hot peppers increased with increasing P levels, but the shoot to root ratio of those elements decreased. The results of this study showed that inoculation of AMF would be effective in promoting growth of hot pepper seedlings and increase transplant adaptation due in part to the resulted higher root development.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.124-137
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• 2018

The main purpose of this study is to find the hotspots of crimes that occur frequently in the space and to derive the appropriate CCTV installation location. One of the characteristics of crime is clustered around past occurrence area, and these crimes are strongly correlated. It is also possible to find the cause of the clusters and the variables that affect the crime through the history of the crime. In addition to the traditional OLS model, spatial differential model including spatial autocorrelation and spatial error model were used to select the variables influencing the five major crime rate, the theft rate and the foreign resident rate. The variables affecting the Five major crimes were positive (+) sign for the welfare and the rate of the bar cluster rate, and negative (-) for the street density. The CCTV area occupies 46% of the hotspots based on the overlapping of the areas where the elderly people are crowded, the bar cluster, many multicultural families, and the areas with low density of street lamps. It turned out. Taking into account the current CCTV operation, the total number of new cases to cover the risk point was 89.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.488-505
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• 2007

The purposes of this research are twofold; 1) to verify spatial differences of tectonic movement using the spatial distribution of earthquakes, and 2) to infer mechanisms that generate spatial accumulation patterns of earthquakes in the Korean Peninsula. The first part of this sequential paper (Park, 2007) argues that the Korean Peninsula consists of four geostructural regions in which tectonic deformation and consequent geomorphological development patterns are different from each other Since this conclusion has been made by terrain analyses alone, it is necessary to verify this suggestion using other independent geophysical data. Because earthquakes are results of movement and deformation of land masses moving in different directions, the distribution of earthquake epicenters may be used to identify the direction and rates of land mass movement. This paper first analysed the spatial distribution of earthquakes using spatial statistics, and then results were compared with the spatial arrangement of geostructural regions. The spatial distribution of earthquakes in the Korean Peninsula can be summarized as the followings; firstly, the intensity of earthquakes shows only weak spatial dependency, and shows large difference even at adjacent regions. Secondly, the epicenter distribution has a clear spatial accumulation pattern, even though the intensity of earthquake shows a random pattern. Thirdly, the high density area of earthquakes shows a clear 'L' shape, passing through Pyeongannam-do, centered at Pyeongyang, and Hwanghae-do, Seosan and Pohang. The correlation coefficient between the density of earthquakes and distance from geostructral region boundaries is much higher than those between the density of fault lines and distance from tectonic division boundaries. Since fault lines and tectonic divisions in the Korean Peninsula are the results of long-term geological development, there is an apparent scale discrepancy to find significant correlations with earthquakes. This result verifies the research hypothesis that the Korean Peninsula is divided into four geostructral regions in which each has its own moving direction and spatial deformation characteristics. The existence of geostructural regions is also supported by the movement parrerns of land masses estimated from the GPS measurements. This conclusion is expected to provide a new perspective to understand the geomorphological developments and the earthquake occurrences in the Korean Peninsula.

• Journal of Life Science
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• v.13 no.1
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• pp.73-82
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• 2003

This experimental research has been done to study the effects of Bojungikgi-tang(BJIKT) on the anti-allergic reaction. We found the several important results from the research which has been performed by two experiments toward immediately type and delayed type in order to study the effects of BJIKT on hypersensitivity response to mice. The results obtained from our research are as following: 1. The survival rate of one group to which we injected only the compound 48/80 is almost 0% according to its density and timing test. In the other hand, the survival rates of the other group to which we injected both of the compound 48/80 and BJIKT are 20%, 10%, 30%, 10%, 40%, and 70% according to 0.025, 0.05, 0.1, 0.25 0.5 and 1(mg/g) of compound 48/80. Time dependency test also shows the 10% and 0% survival rates in 5 and 10 minutes. 2. BJIKT revealed the significantly inhibitory effect on Compound 48/80 induced Mast cell degranulation. 3. BJIKT showed the significantly inhibitory effect in the delayed type hypersensitivity response to picryl chloride. 4. BJIKT showed the significantly inhibitory effect in the delayed type hypersensitivity response to sheep red blood tell. Our research provides the important evidence that BJIKT is benificial to the prevention and treatment of allergy related diseases.

• Journal of Nutrition and Health
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• v.34 no.1
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• pp.30-38
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• 2001

This research was conduced to 1) examine the influence of milk group intake on the dietary, considering dietary diversity and nutrient adequacy, 2) identify which foods truly contribute to the intake of specific nutrients 3) point out the dietary problems of this age group. The subjects were 664(male 357, female 307) healthy toddlers of the ages of 12-36 months, who had neither been taking any medicine-type supplements nor had any diseases that affect the dietary intakes, chosen among the outpatients of university and private hospitals in Seoul and Kyonggi province during Mach-August, 1999. The 24 hour recall method and CAN Pro(food analysis program) were used to analyze the amount of nutrient intake. The grouping of the subjects for the analysis by monthly age was based on the 98 Korean Child growth standard. The results that the milk group intake showed significant negative correlations with the grain group(r=-0.194, p<0.01), the vegetable group(r=-0.115, p<0.01) and the fruit group(r=-0.125, p<0.01). It also showed that the more the milk group intake, the lower the Dietary Diversity Score(r=-0.131, p<0.01), and the more the intake of raw milk, the more dificient the intake of iron(r=-0.211, p<0.01), vitamin A(r=-0.169,p<0.01), vitamin B$_1$(r=-0.078, p<0.05) and vitamin C(r=-0.187, p<0.01). Foods contributory to nutrient intake for of 12-14 months of were mostly infant formula, and the contribution ratio was high. In the age of 15-17 months, the subjects obtained most of the nutrients from raw milk., liquid-type yoghurt, soybean milk, cooked rice, etc. As for iron intake, the age of 21-23 month obtained the most from ionic drinks, and 24-29 months from raw milk, chocolate cakes, ionic drinks, etc. Though the NAR(Nutrient Adequacy Ratio) and MAR(Mean Adequacy Ratio) generally tended to increase accordingly with the DDs, as for nutrients Ca, vitamin A, vitamin B$_1$, and vitamin C the NAR marked the highest when the DDS marked the lowest(due to infant formula). And for iron, even when the DDS was 5 the NAR value was low. Im conclusion, the more the milk group intake, the lower was the dietary diversity. High dependency on infant formula and others from milk group over the age of 12 months proved to result in a decrease of nutritious solid food intake, iron deficiency and a low dietary diversity score, which can lead to an unbalanced diet. Therefore, nutrition education towards mothers/caretakers of toddler is of urgent need, in order to reduce the fluid milk group intake of low nutritional density and to provide various solid foods the children. (Korean J Nutrition 34(1):30-38, 2001)