• Geophysics and Geophysical Exploration
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• v.19 no.1
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• pp.1-10
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• 2016

The hypocenter distribution of microseismic events generated by hydraulic fracturing for shale gas development provides essential information for understanding characteristics of fracture network. In this study, we evaluate how inaccurate velocity models influence the inversion results of two widely used location programs, hypoellipse and hypoDD, which are developed based on an iterative linear inversion. We assume that 98 stations are densely located inside the circle with a radius of 4 km and 5 artificial hypocenter sets (S0 ~ S4) are located from the center of the network to the south with 1 km interval. Each hypocenter set contains 25 events placed on the plane. To quantify accuracies of the inversion results, we defined 6 parameters: difference between average hypocenters of assumed and inverted locations, $d_1$; ratio of assumed and inverted areas estimated by hypocenters, r; difference between dip of the reference plane and the best fitting plane for determined hypocenters, ${\theta}$; difference between strike of the reference plane and the best fitting plane for determined hypocenters, ${\phi}$; root-mean-square distance between hypocenters and the best fitting plane, $d_2$; root-mean-square error in horizontal direction on the best fitting plane, $d_3$. Synthetic travel times are calculated for the reference model having 1D layered structure and the inaccurate velocity model for the inversion is constructed by using normal distribution with standard deviations of 0.1, 0.2, and 0.3 km/s, respectively, with respect to the reference model. The parameters $d_1$, r, ${\theta}$, and $d_2$ show positive correlation with the level of velocity perturbations, but the others are not sensitive to the perturbations except S4, which is located at the outer boundary of the network. In cases of S0, S1, S2, and S3, hypoellipse and hypoDD provide similar results for $d_1$. However, for other parameters, hypoDD shows much better results and errors of locations can be reduced by about several meters regardless of the level of perturbations. In light of the purpose to understand the characteristics of hydraulic fracturing, $1{\sigma}$ error of velocity structure should be under 0.2 km/s in hypoellipse and 0.3 km/s in hypoDD.

• Korean Journal of Environmental Agriculture
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• v.11 no.3
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• pp.185-193
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• 1992

To investigate differences in lead content in soils and paddy rices, affected by air pollutants from the Janghang Smelter, soil samples at the different directions, distances, and depths, surface(0-15cm depth) and subsurface(15-30cm depth) in 1982 and 1990, and rice plants at soil sampling sites in 1990 were separately collected at the Janghang Smelter area affected by combustible waste gas from the smelter chimney. Soil samples were extracted with $4M-HNO_3$ and plant samples were digested with mixture of $HNO_3$ and $HCIO_4$ for analyzing by atomic absorption spectrophotometry. The Pb contents in soils ranged from 10.3 to 644.8mg $kg^{-1}$. The average content in 1990 was higher than that in 1982. The Pb content in soils at sites nearer the center of the smelter was higher than that at sites farther from the center. The highest lead content was found at the east direction, and was low in order of east>north-north east>north east > north. The variation of Pb level in soils at east sites was more considerable than other directions. The Pb level in surface soils was higher than that in subsurface soils. The contaminated radius of Pb was until 3km all at east, north-north east and north east. A significant correlation was found between Pb content in surface soils of 1982 and that in surface soils of 1990, between Pb content in soils and contents of Cd and Zn in soils, and between Pb content in soils and soil properties as organic matter, available silicate, cation exchange capacity, exchangeable $Ca^{++}$, $Mg^{++}$ and $Na^+$. Pb content in brown rice was low in the panicle axis, and brown rice, and Pb content in stem was 3.26 times of that in brown rice. Pb content in brown rice ranged from 2.2 to 9.0 mg $kg^{-1}$.

• Journal of Korean Society of Disaster and Security
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• v.16 no.2
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• pp.15-32
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• 2023

There are some difficulties such as safety problem and need of manpower in measuring discharge by submerging the instruments because of many floating debris and very fast flow in the river during the flood season. As an alternative, microwave water surface current meters have been increasingly used these days, which are easy to measure the discharge in the field without contacting the water surface directly. But it is also hard to apply the method in the sudden and rapidly changing field conditions. Therefore, the estimation of the discharge using the surface velocity in flood conditions requires a theoretical and economical approach. In this study, the measurements from microwave water surface current meter and rating curve were collected and then analyzed by the discharge estimation method using the surface velocity. Generally, the measured and converted discharge are analyzed to be similar in all methods at a hydraulic radius of 3 m or over or a mean velocity of 2 ㎧ or more. Besides, the study computed the discharge by the index velocity method and the velocity profile method with the maximum surface velocity in the section where the maximum velocity occurs at the high water level range of the rating curve among the target locations. As a result, the mean relative error with the converted discharge was within 10%. That is, in flood season, the discharge estimation method using one maximum surface velocity measurement, index velocity method, and velocity profile method can be applied to develop high-level extrapolation, therefore, it is judged that the reliability for the range of extrapolation estimation could be improved. Therefore, the discharge estimation method using the surface velocity is expected to become a fast and efficient discharge measurement method during the flood season.

• Journal of National Security and Military Science
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• s.13
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• pp.687-738
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• 2016

To prepare for the complicated international relationship regarding Korean Peninsula after reunification, this thesis started off with the awareness that Unified Korea should build its international posture and national security at an early stage by determining its appropriate military strength for independent defense and military strategies that Unified Korea should aim. The main theme of this thesis is 'The research on appropriate military strength of the Unified Korean military'. To derive appropriate military strength of Unified Korea, this research focuses on conflict scenario and relative balance strategy based on potential threats posed by neighboring countries, and this is the part that differentiates this research from other researches. First of all, the main objective of the research is to decide appropriate military strength for Unified Korea to secure defense sufficiency. For this, this research will decide efficient military strategy that Unified Korea should aim. Than by presuming the most possible military conflict scenario, this research will judge the most appropriate military strength for Unified Korea to overcome the dispute. Second, after deciding appropriate military strength, this research will suggest how to operate presumed military strength in each armed force. The result of this thesis is as in the following. First, Unified Korea should aim 'relative balance strategy'. 'Relative balance strategy' is a military strategy which Unified Korea can independently secure defense sufficiency by maintaining relative balance when conflicts occur between neighboring countries. This strategy deters conflicts in advance by relative balance of power in certain time and place. Even if conflict occurs inevitably, this strategy secures initiative. Second, when analyzing neighboring countries interest and strategic environment after unification, the possibility of all-out war will be low in the Korean Peninsula because no other nation wants the Korean Peninsula to be subordinated to one single country. Therefore appropriate military strength of the Unified Korean military would be enough when Unified Korea can achieve relative balance in regional war or limited war. Third, Northeast Asia is a region where economic power and military strength is concentrated. Despite increasing mutual cooperation in the region, conflicts and competition to expand each countries influence is inherent. Japan is constantly enhancing their military strength as they aim for normal statehood. China is modernizing their military strength as they aspire to become global central nation. Russia is also enhancing their military strength in order to hold on to their past glory of Soviet Union as a world power. As a result, both in quality and quantity, the gap between military strength of Unified Korea and each neighboring countries is enlarged at an alarming rate. Especially in the field of air-sea power, arms race is occurring between each nation. Therefore Unified Korea should be equipped with appropriate military strength in order to achieve relative balance with each threats posed by neighboring countries. Fourth, the most possible conflicts between Unified Korea and neighboring countries could be summarized into four, which are Dokdo territorial dispute with Japan, Leodo jurisdictional dispute with China, territorial dispute concerning northern part of the Korea Peninsula with China and disputes regarding marine resources and sea routes with Russia. Based on those conflict scenarios, appropriate military strength for Unified Korea is as in the following. When conflict occurs with Japan regarding Dokdo, Japan is expected to put JMSDF Escort Flotilla 3, one out of four of its Japan Maritime Self-Defense Force Escort Fleet, which is based in Maizuru and JMSDF Maizuru District. To counterbalance this military strength, Unified Korea needs one task fleet, comprised with three task flotilla. In case of jurisdictional conflict with China concerning Leodo, China is expected to dispatch its North Sea fleet, one out of three of its naval fleet, which is in charge of the Yellow Sea. To response to this military action, Unified Korea needs one task fleet, comprised with three task flotilla. In case of territorial dispute concerning northern part of the Korean Peninsula with China, it is estimated that out of seven Military Region troops, China will dispatch two Military Region troops, including three Army Groups from Shenyang Military Region, where it faces boarder with the Korean Peninsula. To handle with this military strength, Unified Korea needs six corps size ground force strength, including three corps of ground forces, two operational reserve corps(maneuver corps), and one strategic reserve corps(maneuver corps). When conflict occurs with Russia regarding marine resources and sea routes, Russia is expected to send a warfare group of a size that includes two destroyers, which is part of the Pacific Fleet. In order to balance this strength, Unified Korea naval power requires one warfare group including two destroyers. Fifth, management direction for the Unified Korean military is as in the following. Regarding the ground force management, it would be most efficient to deploy troops in the border area with china for regional and counter-amphibious defense. For the defense except the border line with china, the most efficient form of force management would be maintaining strategic reserve corps. The naval force should achieve relative balance with neighboring countries when there is maritime dispute and build 'task fleet' which can independently handle long-range maritime mission. Of the three 'task fleet', one task fleet should be deployed at Jeju base to prepare for Dokdo territorial dispute and Leodo jurisdictional dispute. Also in case of regional conflict with china, one task fleet should be positioned at Yellow Sea and for regional conflict with Japan and Russia, one task fleet should be deployed at East Sea. Realistically, Unified Korea cannot possess an air force equal to neither Japan nor China in quantity. Therefore, although Unified Korea's air force might be inferior in quantity, they should possess the systematic level which Japan or China has. For this Unified Korea should build air base in island areas like Jeju Island or Ullenong Island to increase combat radius. Also to block off infiltration of enemy attack plane, air force needs to build and manage air bases near coastal areas. For landing operation forces, Marine Corps should be managed in the size of two divisions. For island defense force, which is in charge of Jeju Island, Ulleung Island, Dokdo Island and five northwestern boarder island defenses, it should be in the size of one brigade. Also for standing international peace keeping operation, it requires one brigade. Therefore Marine Corps should be organized into three divisions. The result of the research yields a few policy implications when building appropriate military strength for Unified Korea. First, Unified Korea requires lower number of ground troops compared to that of current ROK(Republic of Korea) force. Second, air-sea forces should be drastically reinforced. Third, appropriate military strength of the Unified Korean military should be based on current ROK military system. Forth, building appropriate military strength for Unified Korea should start from today, not after reunification. Because of this, South Korea should build a military power that can simultaneously prepare for current North Korea's provocations and future threats from neighboring countries after reunification. The core of this research is to decide appropriate military strength for Unified Korea to realize relative balance that will ensure defense sufficiency from neighboring countries threats. In other words, this research should precisely be aware of threats posed by neighboring countries and decide minimum level of military strength that could realize relative balance in conflict situation. Moreover this research will show the path for building appropriate military strength in each armed force.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2003.10a
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• pp.34-63
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• 2003

Occupational and environmental exposure to manganese continue to represent a realistic public health problem in both developed and developing countries. Increased utility of MMT as a replacement for lead in gasoline creates a new source of environmental exposure to manganese. It is, therefore, imperative that further attention be directed at molecular neurotoxicology of manganese. A Need for a more complete understanding of manganese functions both in health and disease, and for a better defined role of manganese in iron metabolism is well substantiated. The in-depth studies in this area should provide novel information on the potential public health risk associated with manganese exposure. It will also explore novel mechanism(s) of manganese-induced neurotoxicity from the angle of Mn-Fe interaction at both systemic and cellular levels. More importantly, the result of these studies will offer clues to the etiology of IPD and its associated abnormal iron and energy metabolism. To achieve these goals, however, a number of outstanding questions remain to be resolved. First, one must understand what species of manganese in the biological matrices plays critical role in the induction of neurotoxicity, Mn(II) or Mn(III)? In our own studies with aconitase, Cpx-I, and Cpx-II, manganese was added to the buffers as the divalent salt, i.e., $MnCl_2$. While it is quite reasonable to suggest that the effect on aconitase and/or Cpx-I activites was associated with the divalent species of manganese, the experimental design does not preclude the possibility that a manganese species of higher oxidation state, such as Mn(III), is required for the induction of these effects. The ionic radius of Mn(III) is 65 ppm, which is similar to the ionic size to Fe(III) (65 ppm at the high spin state) in aconitase (Nieboer and Fletcher, 1996; Sneed et al., 1953). Thus it is plausible that the higher oxidation state of manganese optimally fits into the geometric space of aconitase, serving as the active species in this enzymatic reaction. In the current literature, most of the studies on manganese toxicity have used Mn(II) as $MnCl_2$ rather than Mn(III). The obvious advantage of Mn(II) is its good water solubility, which allows effortless preparation in either in vivo or in vitro investigation, whereas almost all of the Mn(III) salt products on the comparison between two valent manganese species nearly infeasible. Thus a more intimate collaboration with physiochemists to develop a better way to study Mn(III) species in biological matrices is pressingly needed. Second, In spite of the special affinity of manganese for mitochondria and its similar chemical properties to iron, there is a sound reason to postulate that manganese may act as an iron surrogate in certain iron-requiring enzymes. It is, therefore, imperative to design the physiochemical studies to determine whether manganese can indeed exchange with iron in proteins, and to understand how manganese interacts with tertiary structure of proteins. The studies on binding properties (such as affinity constant, dissociation parameter, etc.) of manganese and iron to key enzymes associated with iron and energy regulation would add additional information to our knowledge of Mn-Fe neurotoxicity. Third, manganese exposure, either in vivo or in vitro, promotes cellular overload of iron. It is still unclear, however, how exactly manganese interacts with cellular iron regulatory processes and what is the mechanism underlying this cellular iron overload. As discussed above, the binding of IRP-I to TfR mRNA leads to the expression of TfR, thereby increasing cellular iron uptake. The sequence encoding TfR mRNA, in particular IRE fragments, has been well-documented in literature. It is therefore possible to use molecular technique to elaborate whether manganese cytotoxicity influences the mRNA expression of iron regulatory proteins and how manganese exposure alters the binding activity of IPRs to TfR mRNA. Finally, the current manganese investigation has largely focused on the issues ranging from disposition/toxicity study to the characterization of clinical symptoms. Much less has been done regarding the risk assessment of environmenta/occupational exposure. One of the unsolved, pressing puzzles is the lack of reliable biomarker(s) for manganese-induced neurologic lesions in long-term, low-level exposure situation. Lack of such a diagnostic means renders it impossible to assess the human health risk and long-term social impact associated with potentially elevated manganese in environment. The biochemical interaction between manganese and iron, particularly the ensuing subtle changes of certain relevant proteins, provides the opportunity to identify and develop such a specific biomarker for manganese-induced neuronal damage. By learning the molecular mechanism of cytotoxicity, one will be able to find a better way for prediction and treatment of manganese-initiated neurodegenerative diseases.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.171-181
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• 1999

A field experiments was carried out to investigate the physicochemical properties of soil and cucumber growth in vinyl house when irrigation point was made at 0.2, 1/3, 0.5 and 1.0 bar. The obtained results was summarized as follow: The taxonomic class of the soil used was loam and each content of the required water was 4.4, 7.3, 9.6 and 13.4 mm per each irrigation time at 0.2, 1/3, 0.5 and 1.0 bar treatments in spring culture, respectively. At 0.2 bar and 1.0 bar treatments, interval of irrigation was 2.3 and 14.8 day, the times of irrigation was 37 and 6, and total irrigation volume was 163.5 and 80.3 mm, respectively. After cucumber culture, pH, EC concentration and exchangeable K content of soil at 0.2 bar treatment was distributed near to the level of improvement target while EC, available $P_2O_5$ and exchangeable base content in other treatments were higher compared to improvement target. At 1.0 bar treatment, ratios of the solid and liquid phase were 44.9 and 27.1%, respectively, and bulk density was $1.26g\;cm^{-3}$ which was the highest among the treatments. At 0.2 bar treatment, the ratio of the solid and liquid phase was 41.7 and 22.8%, respectively, and bulk density was $1.09g\;cm^{-3}$ which was the lowest. The root length and radius at 0.2 bar treatment were best, while those at 1/3 bar were worst. At 0.2 bar treatment, the total yield was 7,269 kg and the weight of good products was 5,677 kg which was the highest among treatments. At 0.33 bar treatment, the yield was the lowest with the high ratio of deformity.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.492-501
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• 2007

Coastal disasters have become one of the most important issues in every coastal country. In Korea, coastal disasters such as storm surge, sea level rise and extreme weather have placed many coastal regions in danger of being exposed or damaged during subsequent storms and gradual shoreline retreat. A storm surge is an onshore gush of water associated with a tow pressure weather system, typically in typhoon season. However, it is very difficult to predict storm surge height and inundation due to the irregularity of the course and intensity of a typhoon. To provide a new scheme of typhoon damage prediction model, the scenario which changes the central pressure, the maximum wind radius, the track and the proceeding speed by corresponding previous typhoon database, was composed. The virtual typhoon scenario database was constructed with individual scenario simulation and evaluation, in which it extracted the result from the scenario database of information of the hereafter typhoon and information due to climate change. This virtual typhoon scenario database will apply damage prediction information about a typhoon. This study performed construction and analysis of the simulation system with the storm surge/coastal inundation model at Masan coastal areas, and applied method for predicting using the scenario of the storm surge.

• Journal of Preventive Medicine and Public Health
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• v.27 no.3 s.47
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• pp.447-463
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• 1994

Despite the public health importance of injury and poisoning in terms of its high mortality and incidence, epidemiologic information to be utilized are scarce in Korea. This study was carried out in 1990 on a representative sample population (about 55,000 persons) along with the 6th National Tuberculosis Prevalence Survey in order to estimate the magnitude of injury and poisoning occurrence and to identify its epidemiologic characteristics which can be aided for establishing preventive strategy. Pre-tested and structured Questionnaire was used by trained interviewer to collect data including general information of the person, various information on the injury and poisoning during the past one year such as time and place of its occurrence, its nature and external causes, type of medical institute attended, duration of treatment and outcome of the accident occured. In analysis of the data collected incidence rates per 1000 persons by sex, age group and its nature as well as external causes, and relative frequencies were calculated. The result obtained are as followings; 1. The incidence rate per 1000 was 30 for both sexes, 39 for male and 22 for female, male being 1.8 times more frequent than female. Age adjusted incidences were not much different from the crude rates. Age group specific rate curve showed bimodal shape in both sexes, small peaks in preschool children and higher peaks in older ages. The incidence rate per 1000 people by area was highest in Jeon-bug province (57/1000) and the lowest in Daegu city(11/1000). 2. The place where the injuries occured were road in 46%, within the boundary of house in 25%, and working place in 12% The injuries and poisoning had occured more frequently during the months from March to August of the year than other months. 3. The relatively frequent injuries by its nature were contusion with intact skin surface (19%), fracture of upper limb (13%), open wound of head, neck and trunk (12%) and fracture of lower limb (11%) among males; contusion with intact skin surface (28%), sprains and strains of joints and adjacent muscle (14%), fracture of upper limb (10%) and fracture of lower limb (9%) among females. Higher incidence rate among males than females were fracture of skull (4.5 times), open wound and fractures of limbs ($2{\sim}3$ times). Age specific rate of injuries and poisoning by its nature showed increasing pattern by age in fractures of upper and lower limbs and sprains & strains of joints whereas the age group of 30's showed highest incidence in open wounds of upper limb. Fractures of radius and ulna in upper limb, fractures of tibia & fibula and ankle in lower limb were most frequent among fractures of upper and lower limbs. The frequent injuries among sprains and strains of joints and adjacent muscles were that of ankle, foot and back, and among open wound were that of head and fingers. 4. Relative frequency of injuries and poisoning by external causes showed following order : other accidents (25%), accidental falls (23%), motor vehicle accident (22%) and other road vehicle accident (14%) among males and accidental falls (37%), motor vehicle accident (24%) and other accident (18%) among females. The external causes revealing higher incidences among males than females, were other road vehicle accident (4.8 times), vehicle accident not elsewhere classifiable (4.4 times), accidental poisoning (4.4 times), accidents due to natural and environmental factors (2.8 times), and sucide & self-inflicted injuries (2.8 times). Age specific incidence by external causes for frequent injuries showed that incidence of other accident steadily increased from 10's till age 50's; motor vehicle traffic accident increased from age 20's and dropped after age 60's; on the other hand accidental fall increased strikingly by age. The most frequent external causes among motor vehicle traffic accidents was motor vehicle traffic accident involving collision with pedstrain (69%), pedal cycle accident (30%) and other road vehicle accident (71%) among other road vehicle accidents; falls on same level from slipping, tripping or standing (44%) and other falls from one level to another among accidental falls; accidents caused by machinary (32%) for male and striking against or struck accidentally by objects or person for female among other accidents. 5. Seventy nine percent of the injuries and poisonings were treated in general hospital or hospital/clinic. The duration of treatment ranged from a few days to 123 weeks; the majority(52%) took under 2 weeks, 36% for $3{\sim}8$ weeks and 4% over 21 weeks. 6. The accident resulted in full recovery of normal healthy state in 62%, residual functional defects in 21% and on process of treatment in 16%.

• Journal of Environmental Impact Assessment
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• v.30 no.1
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• pp.13-23
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• 2021

In this study, we performed a Random Walker analysis to predict the Major Movement Paths of otters. The scope of the research was a simulation analysis with a radius of 7.5 km set as the final range centered on the Ansim-wetland in Daegu City, and a field survey was used to verify the model. The number of virtual otters was set to 1,000, the number of moving steps was set to 1,000 steps per grid, and simulations were performed on a total of 841 grids. As a result of the analysis, an average of 147.6 objects arrived at the boundary point under the condition of an interval of 50 m. As a result of the simulation verification, 8 points (13.1%) were found in the area where the movement probability was very high, and 9 points (14.8%) were found in the area where the movement probability was high. On the other hand, in areas with low movement paths probabilities, there were 8 points (13.1%) in low areas and 4 points (6.6%) in very low areas. Simulation verification results In areas with high otter values, the actual otter format probability was particularly high. In addition, as a result of investigating the correlation with the otter appearance point according to the unit area of the evaluation star of the movement probability, it seems that 6.8 traces were found per unit area in the area where the movement probability is the highest. In areas where the probability of movement is low, analysis was performed at 0.1 points. On the side where otters use the major movement paths of the river area, the normal level was exceeded, and as a result, in the area, 23 (63.9%), many form traces were found, along the major movement paths of the simulation. It turned out that the actual otter inhabits. The EN-Simulator analysis can predict how spatial properties affect the likelihood of major movement paths selection, and the analytical values are used to utilize additional habitats within the major movement paths. It is judged that it can be used as basic data such as to grasp the danger area of road kill in advance and prevent it.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.217-224
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• 2021

Purpose: The purpose of this study was to evaluate the porosity of resin modified glass ionomer (RMGI) by different mixing methods. Materials and Methods: Five specimens were prepared for each groups according to capsules and mixing methods. Two RMGI capsule and two mixing machines were used for this study. One resin-modified glass ionomer cement is Fuji II LC (F2LC) and the other is Photac Fil Quick Aplicap (PFQ). For Mixing of RMGI capsule, Rotomix using rotating motion and CM-II using shaking motion were used. After measuring height, radius and mass of specimens, Density was calculated. And porosity was measured using micro-computed tomography (micro-CT). All data were statistically analyzed using T-test, two-way ANOVA to compare between groups at 95% significance level to evaluate the affect of capsule and mixing method on the porosity. Results: The porosity was observed in all specimens generally. And there is significant differece between porosities according to RMGI capsule and Mixing method. The porosity of PFQ was lower than that of F2LC and the porosity of Rotomix was lower than that of CM-II. Conclusion: There was a difference of porosity according to kind of capsules and mixing methods. When using same capsule, less porosity was observed on PFQ than F2LC. When using same mixing mehod, less porosity was observed on Rotomix than CM-II. Using mixing machine of same coporation as that of RMGI capsule did not lead to lower porosity. Therefore, Selecting optimal mixing machine is important.