• Journal of Korea Water Resources Association
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• v.55 no.2
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• pp.111-120
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• 2022

The concept of soil moisture memory was used as a method for quantifying the function of soil to control water flow, which evaluates the average residence time of precipitation. In order to characterize the soil moisture memory, a new measurement index called stored precipitation fraction (F_p(f)) was used by tracking the increments in soil moisture by the precipitation event. In this study, the temporal and spatial distribution of soil moisture memory was evaluated along with the slope and soil characteristics of the surface (0~5 cm) soil by using satellite- and model-based precipitation and soil moisture in the Korean peninsula, from 2019 to 2020. The spatial deviation of the soil moisture memory was large as the stored precipitation fraction in the soil decreased preferentially along the mountain range at the beginning (after 3 hours), and the deviation decreased overall after 24 hours. The stored precipitation fraction in the soil clearly decreased as the slope increased, and the effect of drainage of water in the soil according to the composition ratio of the soil particle size was also shown. In addition, average soil moisture contributed to the increase and decrease of hydraulic conductivity, and the rate of rainfall transfer to the depths affected the stored precipitation fraction. It is expected that the results of this study will greatly contribute in clarifying the relationship between soil moisture memory and surface characteristics (slope, soil characteristics) and understanding spatio-temporal variation of soil moisture.

• Journal of KIISE:Software and Applications
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• v.32 no.10
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• pp.1003-1012
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• 2005

The most significant difference of embedded systems from general purpose systems is that embedded systems are allowed to use only limited resources including battery and memory. Especially, the number of applications increases which deal with multimedia data. In those systems with high data computations, the delay of memory access is one of the major bottlenecks hurting the system performance. As a result, many researchers have investigated various techniques to reduce the memory access cost. Most programs generally have locality in memory references. Temporal locality of references means that a resource accessed at one point will be used again in the near future. Spatial locality of references is that likelihood of using a resource gets higher if resources near it were just accessed. The latest embedded processors usually adapt cache memory to exploit these two types of localities. Processors access faster cache memory than off-chip memory, reducing the latency. In this paper we will propose the enhanced dynamic allocation technique for structure-type data in order to eliminate unused memory space and to reduce both the cache miss rate and the application execution time. The proposed approach aggregates fields from multiple records dynamically allocated and consecutively remaps them on the memory space. Experiments on Olden benchmarks show $13.9\%$ L1 cache miss rate drop and $15.9\%$ L2 cache miss drop on average, compared to the previously proposed techniques. We also find execution time reduced by $10.9\%$ on average, compared to the previous work.

• Journal of Korea Water Resources Association
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• v.45 no.4
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• pp.393-407
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• 2012

This study suggests the results of temporal and spatial variations for rainfall data in the Korean Peninsula. We got the index of the rainfall amount, frequency and extreme indices from 65 weather stations. The results could be easily understood by drawing the graph, and the Mann-Kendall trend analysis was also used to determine the tendency (up & downward/no trend) of rainfall and temperature where the trend could not be clear. Moreover, by using the FARD, frequency probability rainfalls could be calculated for 100 and 200 years and then compared each other value through the moment method, maximum likelihood method and probability weighted moments. The Average Rainfall Index (ARI) which is meant comprehensive rainfalls risk for the flood could be obtained from calculating an arithmetic mean of the RI for Amount (RIA), RI for Extreme (RIE), and RI for Frequency (RIF) and as well as the characteristics of rainfalls have been mainly classified into Amount, Extremes, and Frequency. As a result, these each Average Rainfall Indices could be increased respectively into 22.3%, 26.2%, and 5.1% for a recent decade. Since this study showed the recent climate change trend in detail, it will be useful data for the research of climate change adaptation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.3
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• pp.229-237
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• 2000

According to the functional matrix theory, Delaire proposes that individual occlusal plane was determined by variable effects of teeth, maxilla, mandible, cranium, cranial base and soft tissue matrix including the orofacial musculature. and that there is the ideal occlusal plane determined by the most proper spatial position of maxilla and mandible, functionally and esthetically. This study was designed to find out the relation between Delaire's ideal occlusal plane and muscle activity of masticatory muscles in individuals who have normal maxillo-mandibular relationships. Lateral cephalometric radiographs were taken and his/her individual occlusal plane and ideal occlusal plane were analyzed with Delaire's architectural and structural craniofacial analytic method. For evaluation of muscle activities of masticatory muscles, electromyography of anterior temporal muscle, superficial masseter muscle, and anterior belly of digastric muscle was recorded in fifty Korean normal Angle class I occlusion individuals. According to the average value of ideal occlusal plane, fifty normal Angle class I occlusion individuals were classified into three groups: Ideal occlusal plane group(I group), hyperrotation group(I+ group) and hyporotation group(I- group). The result of this study was as follows: 1. The results of Delaire's architectural and structural craniofacial analysis of lateral cephalography of the fifty Korean normal Angle class I occlusion individuals are that twelve persons(24%) have consistent or parallel with ideal occlusal plane and the average of angular difference was $1.22^{\circ}{\pm}3.69^{\circ}$. 2. There is no significant difference in muscle activities of masticatory muscles during resting(p<0.05), but significant increases of muscle activity of ipsilateral anterior temporal and masseter muscle, contralateral anterior belly of digastric muscle during unilateral chewing and of anterior temporal and masseter muscle during bilateral clenching(p<0.05). 3. To find out the effect of the angular difference between Delaire's ideal occlusal plane and real occlusal plane to muscle activity, muscle activities of masticatory muscles were compared with three groups in each other; I group, I+ group and I- group. The results were no significant differences during resting, unilateral chewing and bilateral clenching.(p>0.05) 4. Although there is no significant differences of masticatory muscle activities among the three groups, the fact that increasing tendency of masseter muscle activity of ideal occlusal plane group(I+) than those of any other groups(I+ and I-) during bilateral clenching was noted. There is only the implication that occlusal plane makes some effects on masticatory muscle activities, espacially that of masseter muscle during bilateral clenching. In conclusion, the hypothesis that occlusal plane is one of the factors which affect the muscle activities of masticatory muscles and that anyone whose occlusal plane consistent with Delaire's ideal occlusal plane has an extraordinary functional advantage in masticatory muscle function cannot be proven with electromyography methods.

• Journal of Korea Water Resources Association
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• v.40 no.11
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• pp.887-898
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• 2007

A physically based semi-distributed model, SWAT was applied to the Chungju Dam upstream watershed in order to investigate the spatial and temporal characteristics of watershed sediment yields. For this, general features of the SWAT and sediment simulation algorithm within the model were described briefly, and watershed sediment modeling system was constructed after calibration and validation of parameters related to the runoff and sediment. With this modeling system, temporal and spatial variation of soil loss and sediment yields according to watershed scales, land uses, and reaches was analyzed. Sediment yield rates with drainage areas resulted in $0.5{\sim}0.6ton/ha/yr$ excluding some upstream sub-watersheds and showed around 0.51 ton/ha/yr above the areas of $1,000km^2$. Annual average soil loss according to land use represented the higher values in upland areas, but relatively lower in paddy and forest areas which were similar to the previous results from other researchers. Among the upstream reaches, Pyeongchanggang and Jucheongang showed higher sediment yields which was thought to be caused by larger area and higher fraction of upland than other upstream sub-areas. Monthly sediment yields at the main outlet showed same trend with seasonal rainfall distribution, that is, approximately 62% of annual yield was generated during July to August and the amount was about 208 ton/yr. From the results, we could obtain the uniform value of sediment yield rate and could roughly evaluate the effect of soil loss with land uses, and also could analyze the temporal and spatial characteristics of sediment yields from each reach and monthly variation for the Chungju Dam upstream watershed.

• Journal of Broadcast Engineering
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• v.5 no.2
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• pp.247-259
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• 2000

This paper introduces a new technique that reduces the search times and Improves the accuracy of motion estimation using high temporal and spatial correlation of motion vector. Instead of using the fixed first search Point of previously proposed search algorithms, the proposed method finds more accurate first search point as to compensating searching area using high temporal and spatial correlation of motion vector. Therefore, the main idea of proposed method is to find first search point to improve the performance of motion estimation and reduce the search times. The proposed method utilizes the direction of the same coordinate block of the previous frame compared with a block of the current frame to use temporal correlation and the direction of the adjacent blocks of the current frame to use spatial correlation. Based on these directions, we compute the first search point. We search the motion vector in the middle of computed first search point with two fixed search patterns. Using that idea, an efficient adaptive predicted direction search algorithm (APDSA) for block matching motion estimation is proposed. In the experimental results show that the PSNR values are improved up to the 3.6dB as depend on the Image sequences and advanced about 1.7dB on an average. The results of the comparison show that the performance of the proposed APDSA algorithm is better than those of other fast search algorithms whether the image sequence contains fast or slow motion, and is similar to the performance of the FS (Full Search) algorithm. Simulation results also show that the performance of the APDSA scheme gives better subjective picture quality than the other fast search algorithms and is closer to that of the FS algorithm.

• Journal of Environmental Impact Assessment
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• v.19 no.3
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• pp.323-333
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• 2010

$PM_{10}$ mass were measured in Gwaebeopdong (inland) and Dongsamdong (seashore) of Busan in summer and fall, 2007 and the 24-hour averaged samples were analyzed to investigate temporal and spatial variability of metallic elements and water-soluble ions in $PM_{10}$. Overall average concentrations of $PM_{10}$ mass during the study period were 72.7 ${\mu}g/M^3$ and 64.3 ${\mu}g/M^3$ in Gwaebeopdong and Dongsamdong, respectively. As for metal elements, averaged concentrations of crustal components, Ca, Fe, K, Mn, and Ti, in Gwaebeopdong exhibited enhancement relative to Dongsamdong. Non-crustal elements, Pb and Cu, displayed elevated levels in Gwaebeopdong while Ni and Zn were observed to be high in Dongsamdong. Averaged nitrate concentration in Gwaebeopdong (6.36 ${\mu}g/M^3$) was greater than in Dongsamdong(5.68 ${\mu}g/M^3$) and both areas had higher level of nitrate in summer than in fall. Averaged sulfate concentrations in Dongsamdong (25.4%) exhibited elevated level relative to Gwaebeopdong (19.4%). Overall average contribution of water-soluble ions to $PM_{10}$ in Dongsamdong (47.5%) was higher than in Gwaebeopdong (37.8%). The average mass fractions of secondary ions in $PM_{10}$ were elevated in Dongsamdong (37.1%) as compared to Gwaebeopdong (31.4%). Equivalent ratio of [${SO_4}^{2-}/NO_3{^-}$] was seen to be lower in Gwaebeopdong (1.39) than that in Dongsamdong (1.79) and consistently higher in summer than in fall for both areas.

• Publications of The Korean Astronomical Society
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• v.14 no.1
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• pp.39-45
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• 1999

We have carried out measurements of 1.2-1.6GHz radio interferences around Seoul Radio Astronomy Observatory located in the campus of Seoul National University. We received interference signals using a pyramidal horn antenna and measured its power using a spectrum analyzer with 1MHz resolution after $\~60dB$ amplification. In order to check the spatial characteristics, we made observations at every $30^{\circ}$ in azimuth at elevation of $30^{\circ}\;and\;60^{\circ}$. Also, in order to check the temporal characteristics, we repeated the all-sky observations five times at every six hours. The results may be summarized as follows: (1) There are strong $({\geq}-20dBm)$ interferences between 1.2 and 1.4GHz. Particularly strong interferences are observed at 1.271 and 1.281GHz, which have maximum powers of -0.34dBm and -0.56dBm, respectively. (2) The characteristics of the interferences do not depend strongly on directions, although the interferences are in general weak at high elevation and in east-west direction. (3) The interferences appear for a very short $(\leq0.01s)$ period of time, so that the average power is much smaller than the maximum power. Strong interferences with large $(\leq-49.0dBm)$ average power have been observed at 1.271, 1.281, 1.339, and 1.576GHz. At these frequencies, the interferences appear repeatedly with a period of $\leq0.1s$ By analyzing the observed power, we find that, for the strongest 1.271GHz interference, the average intensity is $-171dBW/m^2/Hz$ and that the maximum intensity is $-122dBW/m^2/Hz$. If this interference is delivered to the detector without any shielding, then its power would be much greater than the rms noise of a typical line spectrum. Therefore, it is important to shield all the parts of receiver carefully from radio interferences. Also, without appropriate shielding, the sensitivity of a receiver could be limited by the interference.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.4
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• pp.105-111
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• 2010

This paper proposes the recursive algorithm for passive proximity detection system based on signal strength. The system is designed to be used in the smart medicine chest in order to provide location-based service for the senior personnel. Due to the system profile, single receiver and uni-direction communication are applied over the signal attenuation model for the determination of user existence within certain proximity. The performance of conventional methods is subjective to the sight between the transmitter and receiver unless the direction of target is known. To appreciate the temporal and spatial locality of human subjects, the authors present exponential moving average (EMA) to compensate the unexpected position error from the direction and/or environment. By using optimal parameter, the experiments with EMA algorithm demonstrates 32.26% (maximum 40.80%) reduction in average of the error probability with 50% of consecutive sight in time.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.4
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• pp.306-317
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• 2017

Unmanned aerial vehicles (UAVs) became popular platforms for the collection of remotely sensed data in the last years. This study deals with the monitoring of multi-temporal onion growth with very high resolution by means of low-cost equipment. The concept of the monitoring was estimation of multi-temporal onion growth using normalized difference vegetation index (NDVI) and meteorological factors. For this study, UAV imagery was taken on the Changnyeong, Hapcheon and Muan regions eight times from early February to late June during the onion growing season. In precision agriculture frequent remote sensing on such scales during the vegetation period provided important spatial information on the crop status. Meanwhile, four plant growth parameters, plant height (P.H.), leaf number (L.N.), plant diameter (P.D.) and fresh weight (F.W.) were measured for about three hundred plants (twenty plants per plot) for each field campaign. Three meteorological factors included average temperature, rainfall and irradiation over an entire onion growth period. The multiple linear regression models were suggested by using stepwise regression in the extraction of independent variables. As a result, $NDVI_{UAV}$ and rainfall in the model explain 88% and 68% of the P.H. and F.W. with a root mean square error (RMSE) of 7.29 cm and 59.47 g, respectively. And $NDVI_{UAV}$ in the model explain 43% of the L.N. with a RMSE of 0.96. These lead to the result that the characteristics of variations in onion growth according to $NDVI_{UAV}$ and other meteorological factors were well reflected in the model.