• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.87-95
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• 2020

With the advent of the 4^th industrial revolution and the combination of IoT, there have been diverse domestic and foreign researches for the development of construction industry. Especially, in the large-scale earthwork site where many and various construction equipments are put into, the control system between construction equipments is important for the increase of productivity. Thus, after developing the fleet management system for the optimum operation of construction equipments, the problems were checked and improved for each step in the process of application at site. In order to verify the site application process of the fleet management system for the optimum operation of construction equipments, the analysis on the productivity was performed by inputting the data used for the actual site and the site data using this system and then comparing the data through simulation. The analysis was limited to excavator and dump. In the results of the analysis, the rate of work per hour was increased to the range of 4 % while the cost price was decreased to 4 %. Even though the results of the analysis could be different depending on the site applied, the results showing the increase of workload of equipments and the decrease of cost price in the complex project at earthwork site verify the increase of productivity.

• Journal of KIISE:Databases
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• v.31 no.6
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• pp.596-608
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• 2004

A lot of work has been done to reduce disk access time in I/O intensive systems, which store and handle massive amount of data, by distributing data across multiple disks and accessing them in parallel. Most of the previous work has focused on an efficient mapping from a grid cell to a disk number on the assumption that data space is regular grid-like partitioned. Although we can achieve good performance for low-dimensional data by grid-like partitioning, its performance becomes degenerate as grows the dimension of data even with a good disk allocation scheme. This comes from the fact that they partition entire data space equally regardless of distribution ratio of data objects. Most of the data in high-dimensional space exist around the surface of space. For that reason, we propose a new declustering algorithm based on the partitioning scheme which partition data space from the surface. With an unbalanced partitioning scheme, several experimental results show that we can remarkably reduce the number of data blocks touched by a query as grows the dimension of data and a query size. In this paper, we propose disk allocation schemes based on the layout of the resultant data blocks after partitioning. To show the performance of the proposed algorithm, we have performed several experiments with different dimensional data and for a wide range of number of disks. Our proposed disk allocation method gives a performance within 10 additive disk accesses compared with strictly optimal allocation scheme. We compared our algorithm with Kronecker sequence based declustering algorithm, which is reported to be the best among the grid partition and mapping function based declustering algorithms. We can improve declustering performance up to 14 times as grows dimension of data.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.4
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• pp.492-505
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• 2007

Statement of problem: An orthodontic miniscrew implant has been used as a skeletal anchorage for orthodontic treatment. However, any relation among the influence of the cortical bone, morphologic differences of orthodontic miniscrew implants and new bone formation hasn't been made clear yet. Purpose: The purpose of this study was to evaluate whether the orthodontic miniscrew implant could work as an intraoral skeletal anchorage immediately and stably for orthodontic treatment after insertion of it. Material and methods: Two types of orthodontic miniscrew implants were used in this experiment; tapered type and straight type. One hundred and sixty eight orthodontic miniscrew implants were inserted into the tibiae of 21 rabbits and sacrificed on 3, 7, 11, 14, 21 and 28days later after insertion of them to study removal torque values and histologic and histomorphometric analyses. Results: The results were as follows. 1. The removal torque values of the tapered type were higher than those of the straight type in all groups(p<0.05). 2. There wasn't any distinguishing differences between the tapered type and the straight type about the new bone formation percentage. 3. The removal torque values for both the tapered type and the straight type were gradually decreased at early stages of the test but started to increase at the 7 days group of the straight type and the 11 days group of the tapered type. 4. New bone formation percentage was increased gradually for both the tapered and the straight types as time passed(p<0.05). 5. It was found that the tapered type showed lower values in the cortical bone about both the maximum equilibratory stress distribution and the maximum principal stress distribution than the straight type in linear finite elements analysis. Conclusion: According to the research, the removal torque values were decreased at 7 days group of the tapered type and 11 days group of the straight type after the insertion of the orthodontic miniscrew implants in tibiae of rabbits. Considering the human bone activity, it is better to apply the orthodontic force $3{\sim}4$ weeks later than to apply it immediately after the insertion of orthodontic miniscrew implants. Considering that general orthodontic force is about $250{\sim}500$ grams, the tapered type can be worked as a stable skeletal anchor age in an orthodontic treatment even if the orthodontic force is applied on it immediately after the insertion of it.

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.53-60
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• 2023

Recently, along with the improvement of high-speed rail and road design speed, the proportion of tunnel construction work is increasing proportionally. In particular, the construction of long tunnels is rapidly increasing due to the mountainous terrain of our country. In this way, due to the trend of tunnels becoming longer, it is difficult to design and construct tunnels by avoiding fault zones. In the case of tunnel construction in mountainous areas, ground investigation is often difficult even during design due to the topographical conditions, making precise ground investigation difficult, and as a result, the upper part of the tunnel is damaged during tunnel construction. When fault zones, which are vulnerable to weathering, exist, the stability of the tunnel during excavation is directly affected by the fault zone distribution, strength characteristics, and groundwater distribution range. In particular, when a fault zone is distributed in the upper part of a tunnel, damage such as tunnel collapse and excessive displacement may occur, and in order to prevent this in advance, countermeasures must be established through analysis of similar cases. Therefore, in this study, when a large-scale fault zone exists in the upper part of a tunnel, the relationship and characteristics of damage to the tunnel structure were analyzed.

• Journal of Service Research and Studies
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• v.4 no.2
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• pp.1-10
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• 2014

According to recent trends in technological advances and globalization, medical device industry may improve the constitution to meet worldwide medical equipment management system. Also it is holding a strand of mitigation to reach the level of international regulation. In addition, recent legislation tends are to stay limited ranges of industry regulations at least and take as open attitude for integration of new technologies combined medical devices. A greater environmental risk is not likely to work in medical technology, Combinded medical device is used as close to zero risk in most of the human body, which is classified as Class 1. Even medical device such as little or no risk in handling, it is possible to minimize the unnecessary administrative power and a waste of time to occur. For the medical device may be improving people's choices and access, medical equipment operator is expanding to include dealers, because this will be exalted to particular area of the business of the company. In this paper, we investigate the legal prerequisites for the establishment of a medical device. And propose improved regulations in topics in order to facilitate the repair and distribution markets for fair trade.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.484-489
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• 2003

It is well known that root distribution of rice is a crucial factor for nutrient absorbtion and affect by soil fertility management. However, the findings on root distribution are limited due to laborious and tedious work. The characteristics of root distribution were investigated in long-term fertilizer experiment plots that were established in paddy soil, a fine silty family of typic Hal-paqueps (Pyeongtaeg series) in 1967. fertilizer experiment plots of no fertilizer, compost, NPK and NPK+compost plot have been maintained consistently for the past thirty six year and Npk+silicate plot for the past twenty two years. In NPK plot, 150kg N (urea), 100kg -$\textrm{P}_2\textrm{O}_5$ (fused phosphate) and 100kg $\textrm{K}_2\textrm{O}$(potassium chloride) per hectare have been applied. For NPK+silicate plot, 500kg $\textrm{Si}\textrm{O}_2$ (silicate) was applied in addition to fertilizer in NPK plot. For the compost plot, 10,000kg rice straw compost per hectare were applied. Root samples were taken from the positions of hill-center (below hill) and mid-point of four adjacent rice hills at heading stage by cylinder monolith (CM) method. The soil cores were sampled 20cm depth from the soil surface and partitioned four into layers at an interval of 5cm. The soil particles surrounding roots were washed out with tap water, Length and weight of the roots in each soil layer were measured and root length density (RLD), root weight density (RWD), specific root length(SRL) and rooting depth index (RDI) were calculated. Total root length was measured by intersection method. Plant height, tiller and shoot dry weight were the highest in NPK+compost plot. But RLD of hill-center soil cores was the highest in no-fertilizer plots. In the soil cores from mid-point position of four adjacent hills, RLD at 15-20cm soil depth was higher in compost plot than NPK plot. RLD in compost plots showed even distribution compared to those in chemical- fertilizer plots. RWD was the highest in the NPK+compost plot. SRL was the lowest in the NPK+silicate plot. RDI was the highest in the compost plot. Also, in this experiment it was found that the distribution of roots was closely related to the physical properties of the soil as affected by fertilization management.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.251-261
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• 2003

As a part of an on-going project investigating flux of materials in Gomso Tidal Flat, we have monitored temporal and spatial distribution of nitrogen components(TN, PON, DON, DIN) and have sought the relationships with the freshwater input(tidal range, salinity), the biological activities(chlorophyll-${\alpha}$, TP, DIP, silicate) and the resuspended bottom sediment in seawater(SPM) from 1999 to 2000. TN in seawater was 39.05 $\mu\textrm{m}$ol 1$\^$-1/ (31.03∼42.93 $\mu\textrm{m}$ol 1$\^$-1/) without any statistical difference(p<0.05) between the studied periods. Organic nitrogen (DON and PON) occupied 75％, 95％, 73％, and 75％ in April, August, September and November, respectively. DON and PON have been found within the narrow concentration ranges of 11.30∼16.38 $\mu\textrm{m}$ol 1$\^$-1/ and 13.16∼20.04 $\mu\textrm{m}$ol 1$\^$-1/ in spite of severe environmental differences through the studied periods. Dissolved fractions of nitrogen(DON and DIN) occupied 53∼65％ of TN. Only DIN varied with an evident temporal variability: low concentrations(1.325∼1.616 $\mu\textrm{m}$ol 1$\^$-1/) in August and high enrichment(8.377∼14.65 $\mu\textrm{m}$ol 1$\^$-1/) in September. High consumption rate of DIN by phytoplankton and a long-lasted drought probably induced such low concentration of DIN in August. Eventually heavy precipitation probably introduced plenty of new nitrogen sources into Gomso Bay in September. The portion of PON, DON and DIN in the total nitrogen was 40％, 38％ and 22％, respectively. Their contents were in the order of DON>PON>DIN for the year round except PON>DON>DIN only in September. The highest DON portion in August probably due to the active microbial decomposition of organic material in summer. Only in April, some evident negative correlations have been found between chlorophyll-${\alpha}$ and DIN mostly nitrate(-0.64, p<0.01), phosphate(-0.46, p<0.01) and silicate(-0.55, p<0.01). The Si(OH)$_4$/DIN/DIP ratios in the water column suggests the limitation of DIN for the growth of phytoplankton during the dry summer in Gomso Bay, which was the case of August in this work. Even with some difference between the studied periods, the primary factors on the distribution of nitrogen components in seawater overlying the Gomso Tidal Flat have been the tidal range and the freshwater input, but the additional variations were due to the biological activities.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.100-117
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• 2020

National Treasure no. 101, the stupa of State Preceptor Jigwang from the Beopcheonsa Temple Site in Wonju has been transferred from place to place and reassembled several times since it was built. In particular, overall dismantling and repair was carried out in 1957 to restore parts damaged by bombing during the Korean War. Documented information on the repair process and materials used at that time does not exist. However, various types of metal materials used for this stupa have been identified during conservation work. Besides clamps anchor bolts, 9mm-thick circular rebars were mainly used for joining the parts of this stupa, while circular rebars and wires of various thicknesses were used for joining the parts with mortar restoration materials. Although deformed bars are typically used for stone pagodas classified as architectural structures, smooth circular rebars were used in this case. In terms of restoration using mortar, material shapes were transformed, bound alternately, and twisted irregularly to improve bonding strength and coherence in order to insert restoration materials and to bolster structural weaknesses. In addition, metallographic analysis showed the material to be hypo-eutectoid steel with low carbon content. Many non-metallic inclusions in the shape of drops of different sizes were included, which do not affect the whole elemental composition due to the very small quantities involved. Qualitative and EPMA analysis of Mn and S, which were not identified by SEM-EDS area analysis, established an even distribution of MnS in crystal grains of the microstructure, regardless of the shape of the samples. It is presumed that secondary homogenization and softening might have been conducted after manufacturing to facilitate the working process. Furthermore, in consideration of properties indicating that the thinner the steel is, the less carbon content contained and the greater the elasticity and elongation, it is judged that restoration work was ordered.

• Journal of The Korean Astronomical Society
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• v.49 no.1
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• pp.25-35
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• 2016

Multiple color selection techniques are successful in identifying quasars from wide-field broadband imaging survey data. Among the quasars that have been discovered so far, however, there is a redshift gap at 5 ≲ z ≲ 5.7 due to the limitations of filter sets in previous studies. In this work, we present a new selection technique of high redshift quasars using a sequence of medium-band filters: nine filters with central wavelengths from 625 to 1025 nm and bandwidths of 50 nm. Photometry with these medium-bands traces the spectral energy distribution (SED) of a source, similar to spectroscopy with resolution R ~ 15. By conducting medium-band observations of high redshift quasars at 4.7 ≤ z ≤ 6.0 and brown dwarfs (the main contaminants in high redshift quasar selection) using the SED camera for QUasars in EArly uNiverse (SQUEAN) on the 2.1-m telescope at the McDonald Observatory, we show that these medium-band filters are superior to multi-color broad-band color section in separating high redshift quasars from brown dwarfs. In addition, we show that redshifts of high redshift quasars can be determined to an accuracy of Δz/(1 + z) = 0.002 - 0.026. The selection technique can be extended to z ~ 7, suggesting that the medium-band observation can be powerful in identifying quasars even at the re-ionization epoch.

• Journal of agricultural medicine and community health
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• v.40 no.4
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• pp.240-249
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• 2015

Objectives: Farmers are known to be exposed to a variety of allergens related to the work environment. This study was conducted to determine the sensitization rates as well as South Korea that they are sensitized to certain allergens farmers through the skin prick test. Methods: By targeting a total of 1143 people living in the rural town of Gyeonggi Province, it was conducted a questionnaire containing demographic and occupational risk factors and underwent skin prick tests with 15 types of allergens(including positive and negative controls). Multivariable logistic regression analysis was used to analyze the association between occupational risk factors and skin prick test positivity. Results: Except for the 30 people whose result is invalid, positive rate of the skin prick test was 18.6% in 1,113 people. The species of house dust mite, Dermatophagoides pteronyssinus and Dermatophagoides farinae was the highest at 8.7% and 8.6%. After adjusted by age, gender, smoking and education level, odds ratio of flower plant farmers is 4.467(95% CI: 2.094-9.527) and fruit farmer is 2.275(95% CI: 1.096-4.721). In addition, the rate of sensitization to grass pollen mixture of the flower plant farmers is significantly higher(15.9%, p<0.001) than other allergens. Conclusions: Even farmers, the rate of sensitization to allergens related to the general environment, such as house dust mite is relatively dominant. However, given the presence of potential cross-reactivity between the allergens or distribution showed that the unique aspects of allergen sensitization in the flower growers, occupational cause is not be completely ruled out.