• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.897-903
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• 2010

Used gas to the vehicle fuel are the problems of the 'survival' beyond the 'quality of life' improvements and revive a new paradigm of 'sustainable development' which pursues economic development in harmony with environmental conservation. However, the fatalities caused by explosions and fires increases every year with the increase in the use of LPG; gas accidents in large-scale storage facilities also cause severe damage to property. In this study, a suitable storage tank is designed in which the surface area of the fuel exposed to flames is minimized in order to prevent explosions; thus, the occurrences of explosions in underground storage tanks can be minimized. According to the optimum design of storage tank obtained in this study, underground containment space was minimized; the minimized diameter and length of a 20-ton storage tank was 3 m and 4.83 m, respectively. Thus, safety was ensured since surface area exposed to flames decreased by 89.4%, which is less than the exposed surface area in the currently used storage tanks.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.457-471
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• 2015

A domestic cutterhead with the diameter of 3.6 m was designed and manufactured in this study. Then, it was attached to an existing earth-pressure balanced shield TBM to excavate a cable tunnel with the length of 1,275 m. Especially, the procedures for TBM cutterhead design and its corresponding performance prediction were also summarized. From field data analyses of the refurbished shield TBM, its maximum advance rate was recorded as 14.4 m/day. Penetration depths of disc cutters were found to be approximately 4 mm/rev, which is equal to the maximum penetration depth designed for the strongest rock strength condition in the target tunnel. Every TBM operating thrust and cutter normal force during TBM driving was much smaller than their corresponding maximum capacities. When cutter acting forces recorded in the field were analyzed, their prediction errors by the CSM model were very high for weak rock conditions. In addition, rock strength showed very close relationships with cutter normal force and penetration depth.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.333-340
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• 2004

The use of the othotropic steel deck is steadily increased due to the advance of the technology in the steel bridges which recently have been longer. But the othotropic steel deck bridge is the structure that is very fragile to the fatigue, especially, the fatigue crack at the cross of the longitudinal rib and transversal rib is one of the biggest problems that othotropic steel deck bridges have. The causes of these fatigue cracks come from the secondary stress on out-plane behavior of transversal rib. In this study, we conducted the experiment to find the optimal details to improve fatigue strength on intersection between longitudinal rib and transversal rib in the othotropic steel deck bridge through numerical analysis using the experiment of the fatigue in the 3-dimensional real structure and program LUSAS. As a result of study, it is showed that the details of the korean standard section attached with a curved bulkhead plate is the most profitable. And, it is indicated that the stress which is generated when the reform improved section by parametic study can be reduced by about 50% at most or more. Along with the reduced stress and the longer interval between transversal ribs(G=400), the decreased steel amount by 4% and the shortened welding length by 34% make it possible to produce the othotropic steel deck bridge which is strong against fatigue.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.225-225
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• 2017

This study is to investigate the effect of split application and adapted fertilization application cultivation in stable medicinal herbs production of Acorus graminens S. And it accomplished one's purpose to GAP guide manual established standard method of cultivation technology, contribute to the enlargement of farm's income. Method of fertilization application were conducted under five condition compose to standard application(N-P-K-Compost: fermented mixed oil cake fertilizer applied at $4-2-6-300kg.10a^{-1}$, twofold application(N-P-K-Compost applied at $8-4-12-600kg.10a^{-1}$) cultivation. Compost (fermented mixed oil cake fertilizer) and fused phosphate applied at 100% of basal fertilizer in April 14. The split application level of standard application and twofold application(N-K) applied at 100%, 50%, 40% of basal fertilizer in April 14, 50% and 40% of top dressing were three times application (N-K) in June 1, July 15, August 15, 25% and 20% respectively. Transplanting with Naju varieties in May 12 by growing pot seedling for 40 days in 2015. Planting density were spaced 30 cm apart in rows 30 cm apart with black vinyl mulching on open cultivation. Plot design randomized block 3 repetition. Therefore, growth characteristics by 50% and 40% of top dressing were three times application (N-K) compared to standard application and twofold application (N-K) applied at 100% basal fertilizer, aerial part as a result were so many such amount of growth as number of leaf per plant, etc., Length of diameter and main root of subterranean part growth increment rising highest. Dried roots yields treated standard fertilizer 100% application($250kg.10a^{-1}$) compared to 100% from twofold application (N-K) applied at 50% basal fertilizer, 50% and 40% of top dressing were three times application increased by 16%, 20%. respectively.

• Journal of Hospice and Palliative Care
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• v.17 no.4
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• pp.289-300
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• 2014

Purpose: The aim of this research was to explore nurses' knowledge of and attitudes toward pediatric palliative care (PPC) in Korea. Methods: A descriptive cross-sectional design was used. A total of 196 participants were recruited from the ELNEC-PPC course held in Seoul, Korea. All participants completed a 20-item survey questionnaire which assessed knowledge of and attitudes toward PPC using a 7-point Likert scale. Results: Nurses' knowledge of PPC correlated with their educational level and work experience in the pediatric unit and hospice care unit. The work experience in the pediatric unit, career length in PPC and completion of palliative education course made differences in the attitudes toward PPC. Married nurses scored significantly higher on the parental rights in determining palliative care service for their child, and nurses with master's degree or higher showed a higher level of understanding of and attitudes toward the differences between PPC and adult palliative care. Conclusion: The factors influencing nurses' knowledge of and attitudes toward PPC need be considered to develop a pediatric palliative training program.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.105-115
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• 2010

Recently, High-rise building are irregular-shaped to be city landmarks and function as vertical cities to enable the efficient use of land. 3T (Twisted, Tilted & Tapered) designs are being suggested for irregular buildings and studies to develop new structural system have been actively made to satisfy slender shape ratio. In diagrid system, not only gravity load but also lateral load is delivered based on the triangular shape of diagrid, so most of columns are eliminated. Because shearing force is delivered by the axial behavior (tensile/compressive) of diagrid to minimize shearing deformation, the system is more applicable to irregular buildings than existing system where shearing force is delivered by the columns. In this study, the process of selecting connection details and the structural safety of the selected details are verified using the finite element analysis with focus given to the construction overview of the Cyclone Tower. However, the relersed methods of stress concentration are suggested and the performance of stress concentration relieves that it's suggested for the appropriate cap plate thickness and extended length.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.1
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• pp.8-18
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• 2000

We presented a BGA(Ball Grid Array) package for RF circuit modules and extracted its electrical parameters. As the frequency of RF system devices increases, the effect of its electrical parasitics in the wireless communication system requires new structure of RF circuit modules because of its needs to be considered of electrical performance for minimization and module mobility. RF circuit modules with BGA packages can provide some advantages such as minimization, shorter circuit routing, and noise improvement by reducing electrical noise affected to analog and digital mixed circuits, etc. We constructed a BGA package of ITS(Intelligent Transportation System) RF module and measured electrical parameters with a TDR(Time Domain Reflectometry) equipment and compared its electrical parasitic parameters with PCB RF circuits. With a BGA substrate of 3${\times}$3 input and output terminals, we have found that self capacitance of BGA solder ball is 68.6fF, and self inductance 146pH, whose values were reduced to 34% and 47% of the value of QFP package structure. S11 parameter measurement with a HP4396B Network Analyzer showed the resonance frequency of 1.55GHz and the loss of 0.26dB. Routing length of the substrate was reduced to 39.8mm. Thus, we may improve electrical performance when we use BGA package structures in the design of RF circuit modules.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.63-70
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• 2001

We demonstrate the MMIC (monolithic microwave integrated circuit) frequency doublers generating stable and low-cost 29 GHz local oscillator signals from 14.5 GHz input signals. These devices were designed and fabricated by using the M MIC integration process of $0.1\;{\mu}m$ gate-length PHEMTs (pseudomorphic high electron mobility transistors) and passive components. The measurements showed S11 or -9.2 dB at 145 GHz, S22 of -18.6 dG at 29 GHz and a minimum conversion loss of 18.2 dB at 14.5 GHz with an input power or 6 dBm. Fundamental signal of 14.5 GHz were suppressed below 15.2 dBe compared to the second harmonic signal at the output port, and the isolation characteristics of fundamental signal between the input and the output port were maintained above :i0 dB in the frequency range 10.5 GHz to 18.5 GHz. The chip size of the fabricated MMIC frequency doubler is $1.5{\times}2.2\;mm^2$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.5
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• pp.40-45
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• 2008

In this paper, a microstrip linear tapered slot antenna is designed. A tapered slot antenna(TSA) has many advantages such as low profile, low weight, easy fabrication, and compatibility with monolithic microwave integrated circuits(MMIC). In addition, it has demonstrated multi octave bandwidth, moderately high gain, and symmetrical E- and H-plane beam patterns. A feed network is implemented with transition between a microstrip and a slot line for the microstrip linear tapered slot antenna. The transition is consist of two sides. One side has a microstrip line, the other side has a slot line. The dimensions of the microstrip and slot line are ${\lambda}_m/4$ and ${\lambda}_s/4$ at the center of the cross section of the microstrip and slot line. In order to get broad bandwidth antenna characteristics, the tapered length is chosen as $4{\lambda}_o$ and termination width is chosen as $1.75{\lambda}_o$. Experimental results show that the microstrip tapered slot antenna has symmetrical E- and H-plane beam patterns with around 5GHz of bandwidth at center frequency of 5.0GHz.

• Journal of Environmental Science International
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• v.18 no.4
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• pp.463-471
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• 2009

A study on vegetation in the Mangyeong River and Dongjin River basins and the surrounding regions of the Saemangeum Reclaimed Land was conducted in a series of efforts to determine the expected ecological changes in the salt marshes, to restore their vegetation, to explore the restoring force of halophyte, to examine the community mechanism and, ultimately, to rehabilitate marshy land vegetation along the lakeside, coastal dune and salt marshes of the Saemangeum Project Area. The findings of the study may be summed up as follows: Five species such as Suaeda japonica, Salicornia herbacea, Atriplex gmelini, Aster tripolium and Suaeda asparagoides that are mostly distributed in the estuary of the Saemangeum Reclaimed Land were analyzed to examine the mechanism of halophyte to maintain their community. To find out the strategies of plants for survival and the cause of forming community structure, a research was made as for appearance ratio of biomass, root lengths and germination. With regard to biomasses of halophyte, the biomass of Suaeda japonica increases rapidly, while Salicornia herbacea adopts a strategy of unstable growth pattern by which the biomass increases slowly in parallel with its slow speed of growth since initial appearance of young sapling. In contrast, Suaeda asparagoides, Atriplex gmelini and Aster tripolium choose to adapt themselves to environment promptly by being transformed into life form of annual or biennial plant, a pattern that is presumed to be favorable and stable for survival in the later stage of growth. In short, there is a sharp distinction among the 5 species: i.e. Suaeda japonica that begins to grow fast in the length of surface and underground section but slows down from the mid-stage on; Salicornia herbacea that grows slowly in the beginning step but starts to step up from the middle onward; Atriplex gmelini and Aster tripolium growing slowly in the initial stage but fast later on; and Suaeda asparagoides that turns from the constant growth in the beginning to rapid growth in the later period. The outcomes of the analysis into status of growth and influencing factors of Suaeda japonica in the sowing field that is most widely prevalent in the Saemangeum Reclaimed Land as a sort of ecological pioneer in the salt marshes showed that the average size of grass lands, density and number of individuals increase in the natural sowing field as well as in the plowing field regardless of their physical as well as physico-chemical features of the soil as the season progresses from June to October of a year.