• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.120-129
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• 2020

This paper aims to benchmark the United States' LRIP, the country's initial production policy, and provide a Korean version of such policy which reflects the circumstances of the country's weapon system research & development(R&D) and acquisition procedures. The research suggests measures to improve the country's initial production policy in a direction that the policy could execute two stage continuously: (1) employment test & evaluation(OT&E), conducted on prototypes during the development stage, and (2) field employment tests(FT), conducted on initial products during the production stage. In addition, the research provides an equation calculating the optimal number of initial test products to be produced, applying statistical theories of t-distribution. The research aims to be used a reference to calculate the optimal number of initial products to be produced for testing in order to improve future national defense acquisition systems and the stable R&D of weapons systems.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.241-263
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• 2022

The conventional wind and twisted-wind effect on aerodynamic properties of neighboring buildings arranged in side-by-side and tandem systems at 2B and 5B spacings are systematically investigated by large eddy simulation. Different physical interactions between different wind profiles and neighboring buildings will be deeply understood. The neighboring-building system under two different types of wind profiles, i.e., conventional wind profile (CWP), twisted wind profiles (TWP) with the maximum twisted angle of 30°, is used to evaluate the variation of physical mechanism between wind and buildings. Aerodynamic characteristics including mean and RMS pressure coefficient, and velocity field were systematically analyzed and compared between different scenario. It was found that the distribution of mean pressure, root-mean-square x velocity and the streamline of wind flow for TWP greatly deviated from CWP, and the effect of TWP on the downstream building, was drastically different from that of CWP, such as the size of vortexes after the lower stream building being bigger when exposed to TWP, and the mean pressure distribution on the building surfaces are also different. Moreover, evidence of buildings arranged in side-by-side and tandem configurations having interchangeable properties under TWP was also discovered, that two buildings being arranged side-by-side exposed to TWP could be identified as being arranged in tandem with a different wind twist angle, or vice versa.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.159-163
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• 1993

This research was conducted at the Crop Experiment Station to determine the changes of weed flora under direct seeded rice cultivation in dry paddy field from 1989 to 1992 and to establish an effective weed control strategy in direct seeded rice cultivation. With the continuous rice growing under direct seeded rice cultivation in dry paddy field, there were more occurrence in grasses and annual weeds while broadleaf and perennial weeds were diminished. The predominant weeds were aquatic weeds such as Eleocharis kuroguwai, Echinochloa crusgalli, and Monochoria vaginalis in machine transplanted rice paddy field while there were predominant of semi aquatic weed species such as E. crusgalli, Digitaria sanguinalis, Bidens tripartita, Aeschynomene indica, and Arthraxon hispidus in continuous direct seeded rice cultivation in dry paddy condition. Based on the vegetative analysis of weeds in terms of simpson index and community dominance, there was more distribution of weed species in direct seeded rice cultivation on dry paddy condition while only distributed with 1-2 weed species in machine transplanted rice paddy field. In similarity coefficient, there was a gradual increase up to 67% of weeds with the continuous direct seeded rice cultivation in dry paddy condition for 4 years starting from 41% of similarity coefficient.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.6-12
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• 2012

A fact-finding survey was conducted to obtain the basic information on nation-wide weed distribution and farmer's opinions to weed control strategy in paddy field. Most respondents considered Echinochloa spp., Monochloa vaginalis, Sagittaria trifolia, and Scirpus juncoides etc. as dominate weeds in paddy fields. And herbicide resistant weed species were M. vaginalis, S. juncoides, E. oryzicola and S. pygmaea etc. Purchase guidances for herbicide selection, experience of farmers was 34.0% and dealers recommendation was 33.9% at farmer's level. And paddy field herbicides application frequence were one time 15.6% but twice 75.6%. Preferred herbicides were ranked in the following order: oxadizone 12% EC, butachlor 5% GR, butachlor 33% CS, mefenacet pyrazodulfuron-ethyl 21.42% SC, and oxadiargyl 1.7% EC etc. in paddy fields. And in most preferred foliar herbicide were bentazone MCPA 38.6% SL and bentazone cyhalop-butyl 18.5% ME, 48.5% and 22.3%, respectively.

• Journal of The Korean Astronomical Society
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• v.50 no.3
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• pp.61-70
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• 2017

We study the angular correlation function of bright ($K_s{\leq}19.5$) Extremely Red Objects (EROs) selected in the Subaru GTO 2$deg^2$ field. By applying the color selection criteria of $R-K_s$ > 5.0, 5.5, and 6.0, we identify 9055, 4270, and 1777 EROs, respectively. The number density is consistent with similar studies on the optical - NIR color selected red galaxies. The angular correlation functions are derived for EROs with different limiting magnitude and different $R-K_s$ color cut. When we assume that the angular correlation function $w({\theta})$ follows a form of a power-law (i.e., $w({\theta})=A{\theta}^{-{\delta}}$), the value of the amplitude A was larger for brighter EROs compared to the fainter EROs. The result suggests that the brighter, thus more massive high-redshift galaxies, are clustered more strongly compared to the less massive galaxies. Assuming that EROs have redshift distribution centered at ~ 1.1 with ${\sigma}_z=0.15$, the spatial correlation length $r_0$ of the EROs estimated from the observed angular correlation function ranges ${\sim}6-10h^{-1}Mpc$. A comparison with the clustering of dark matter halos in numerical simulation suggests that the EROs are located in most massive dark matter halos and could be progenitors of $L_{\ast}$ elliptical galaxies.

• Journal of the Korean Institute of Landscape Architecture
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• v.19 no.2
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• pp.65-74
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• 1991

The purpose of this study was to find the basic application of Disporum genus in landscape-arc-hitectual space. Environment of native site (Daeducksan, Piseulsan) and growth characteristics of experiment plot were investigated and analyzed in this study. The results of this study were as follows; 1. In the case of environment of native site, the relative light intensity was about 10% and distribution of species were primarily north slope. Gradient of Daeducksan and Piseulsan were 10$^{\circ}$, 18$^{\circ}$ Soil textures was Lic both and field capacity of Daeducksan and Piseulsan were 69%, 73.5%. The soil pH of Daeducksan and Piseulsan were 6.1 and 5.8. The both content of organic matter and C.E.C. were high markedly. The P2O5 content of Daeducksan showed high but total nitrogen showed nearly the same level when comparing with the common dry field condition. 2. In tree layer, Daeducksan composed of broadleaved forest of 80% involving Quercus variabilis, and Piseulsan composed of coniferous forest of 80% involving Pinus densiflora on the other hand. Daeducksan, therefore, was more appearance species than Piseulsan in herbaceous layer. 3. Result in ANOVA Test, significance followed with light intensity was recognized in plant height, leaf width, leaf length, leaf thick and No. of leaf, while in the case of soil was not. Plant height was longest in 1% and leaf width, leaf length was largest in 25%. Therefore ornamental value of leaf was the very best in 25%. 4. Result in correlation coefficient analysis, plant height was correlated leaf width, leaf length. The longer plant height, the smaller leaf width, leaf length. In relative light intensity of 1%, flower was hardly expected because of the more shade, the less flower. Disporum smilacinum is expected great use as ground covers in the shades of tall-building or hdavy woods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.821-828
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• 2006

In this paper, we investigated SAR(Specific Absorption Rate) value variation by the position and size of the loop-type ground located in a test mobile handset. We carried out simulations on SAR value with loop-type grounds in rear case of a mobile handset, and obtained results showed that different positions and sizes of loop-type grounds had different SAR values. Among investigated positions and sizes of loop-type grounds, the small size case-C showed the best performance; i.e., it showed a decrease efficiency of 8.70 %. And in this case, it showed the highest induced electric-field distribution in the loop-type ground. In the simulation, the folding angle was set to $160^{\circ}$.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.395-401
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• 1993

Lower Ordovician rock samples were collected from 23 sites located at the Okcheon non-metamorphic zone, near Taeback and Yeongweol areas, southern part of the Korean Peninsula. A characteristic magnetic component was obtained from four sites. This stable direction ($Dm=-19.4^{\circ}$, $Im=24.1^{\circ}$) which is carried by hematite of very high temperature $679^{\circ}C$), successfully pass both of reversal test and paleopole reliability test, and is regarded as a primary direction. The remagnetized components can be divided into three on the basis of their characteristic directions and magnetic minerals. The first which is carried by hematite, magnetite and pyrrhotite, is widely found at the whole sites. It shows syn- or post-tectonic remagnetization according to strongly negative fold test and distribution between Mesozoic and present field directions. The second, in situ, is distinguishable from the present field direction. After bedding correction, it is identical to Late Triassic to Early Jurassic direction. Its magnetic carrier is considered to be a single component hematite, which may be acquired by pre-tectonic CRM in the Okcheon orogenic zone. The third, which is carried by magnetite and hematite, is characterized by stable reversed direction. These minerals may be acquired by the thermal or chemical process in unknown period. Paleopole position is $169.2^{\circ}E$ in longitude and $59.9^{\circ}S$ in latitude, which indicates that the study area was located at $12.6^{\circ}S$ in paleo-latitude and belonged to northern end of the Gondwana in Early Ordovician.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.131-145
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• 2013

The purposes of this research are : to analyze biotop type and carry out conservation value assessment in study areas, Daegu Science Park national industrial complex; to supply basic data for the landscape ecological planning; and to improve the application of assessment model with the development of Biotop Value Assessment Tool (B-VAT). The result is as follows. First of all, the field survey showed 434 species of flora and 220 species of insecta. According to the result of biotop type analysis in the biotop classification system with field survey, 13 biotope groups and 63 biotope types were classified. In the map of biotop type classification, readjusted farmland biotop(FA) was prevalent and forest biotop(E) was shown to the southeast side of the site. Next, according to the first assessment with B-VAT, total 19 biotop types including natural river(BA) with abundant plants had I grade and total 16 biotop types such as vegetable garden adjacent to river(BC) had V grade. In terms of the second assessment, we analyzed total 30 areas, total 82 areas, respectively, which had special meaning for the conservation of species and biotop(1a, 1b) and which had meaning for the conservation of species and biotop(2a, 2b, 2c). This research will be a basic data, which can solve the damage problem systematically and control it landscape-friendly with biotop classification and assessment which we developed. In particular, we expect that biotop value assessment tool(B-VAT) with GIS will be a great contribution to popularity compared with the value model by complicated algorism such as adding-matrix, weight and equal distribution. In addition, this will save the time and improve the accuracy for hand-counting.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.3-5
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• 2001

Racetrack coils are used in many areas of superconductivity applications such as generators, motors, maglev, wiggler magnets and so on. The fabrication and characteristics of race-track type High Tc Superconducting (HTS) magnets were carried out. The Magnet is composed of 3 pancake coils wound by 37-filamental Bi-2223/ Ag-alloy tapes. Quench current ($I_q$) of both whole magnet and 3 pancake coils were measured. At 77K under the self-field, $I_q$ of magnet was 12A, while in the case of middle pancake coil, $I_q$ was 15A. The upper pancake coils of racetrack magnet with iron plates, magnet having optimized current distribution and initial magnet are compared with each other through 3D FEA, manufacturing and testing these magnets. The measured performance of the upper pancake coil #3 with iron plates improved by 50% on the basis of initial pancake coil #3. Quench current ($I_q$) of field winding was 12A. In addition, the fabrication processes and the characteristics of HTS magnet are described.