• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.3
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• pp.42-52
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• 2015

Since the tax-free system for overseas laborers was implemented in 1974, the tax-free limits of international air crew, overseas construction workers and crewmen of deep-sea fishing ships and ocean-going ships had been identical by 2005, but there are big differences, currently. The Ministry of Strategy and Finance pointed out the poor working environments and international competitiveness of the industries to explain the reason for the differential tax-free limit. From this perspective, the fairness of the tax-free system for overseas laborers was analyzed. This is an empirical study, based on the objective fact. The study finding showed that international air crew were working in the structural flight work environments to threaten the right of health due to jet lag and excessive exposure to high-altitude cosmic radiation. Therefore, it was analyzed there should be a proper system reform to apply the tax-free limits to international air crew which are identical to those applied to overseas construction workers and crewmen of deep-sea fishing ships and ocean-going ships, for a fair taxation.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.424-434
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• 2012

This paper presents a path planning algorithm of the unmanned aerial vehicle for the neutralization of the enemy firepower. The long range firepower of the ememy is usually located at the rear side of the mountain which is difficult to bomb. The path planner not only consider the differential constraints of the Unmanned Aerial Vehicle (UAV) but also consider the final approaching angle constraint. This problem is easily solved by incorporating the analytical upper bounded continuous curvature path smoothing algorithm into the Rapidly Exploring Random Tree (RRT) planner. The proposed algorithm can build a feasible path satisfying the kinematic constraints of the UAV on the fly. In addition, the curvatures of the path are continuous over the whole path. Simulation results show that the proposed algorithm can generate a feasible path of the UAV for the bombing mission regardless of the posture of the tunnel.

• The Korean Journal of Ecology
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• v.16 no.3
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• pp.239-259
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• 1993

The vegetation types and distributional characteristics of the forest vegetation on Mt. Ilwol were investigated by the Z-M school method. Geographical distribution of the vegetation was a central/montane(CEMO) type of the Korean Peninsula subtype. The forest was classified into five vegetation units: Artemisio-Quercetum mongolicae (Artemisio-Quercetum typicum subass. nov., Artemsio-Quercetum pinetosum dens~florae subass. nov. ). Lychno-Quercetum mongolicae (Lychno-Quercetum Calamagrostetosum arundinaceae subass. nov.. Lychno-Quercetum ligularetosum f~scherii subass. nov.), Fraxinus rhynchophylla community, Quercus variabilis community and Larix leptolepis afforestation. Species with percentage constance degree more than 61% are Quercus mongolica (89.5%, V), Lespedeza maximowiczii (73.7%, IV), Isodon japonicus(73.7%, IV), Fraxinus rhynchophylla (68.%, IV), Arlemisia stolonifera (65, 8%, IV), etc. Artemisio-Quercetum mongolicae was chiefly distributed on the ridge lines of low altitudes (570~700m) and on the ground with exposed rocks in sloping surface (800~1, 000m). Both Fraxinus sievoldiana and Rhododendrou schlippenbachii of the Artemisio-Quercetum mongolicae showed a predominant condition all over the subtree and shrub layers. Of Artemisio-Quercetum pinetosum densifloraes, Pinus densiflora becomes powerful over the tree layer and, on the other hand, Quercus mongolica over the subtree layer. Lychno-Quercetum mongolicae was distributed somewhat on the humid region of the high altitude area (840~1.200m). Fraxinus rhynchophylla community was chiefly distributed in the vicinity of the ravines. Quereus rariabilis community was distributed at subxeric slope on southeast side of the mountain. Larix leptolepis has been reforested at the ecotone between Artemisio-Quercetum mongolicae and Lychno-Quercetum mongolicae. Percentage cover degrees of the subtree layer In Lychno-Quercetum mongolicae, Quereus rariabilis community and Larix leptolepis afforestation were relatively low, 15.3%, 5% and 2.5%, respectively.The contents of moisutre and organic matter in the soil were much higher in Luchno-Quercetum monogolicae and Larix leptolepis afforestaion than in the other communities. Contents o Ca, Mg, K and the available phosphorus were relaively high compared with forests of the other area. This result seems to be influenced by a forest fire. As the altitude increases, the moisure content in the forest soil also increases.

• Korean Journal of Remote Sensing
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• v.34 no.2_1
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• pp.191-201
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• 2018

In this present study, we, for the first time, retrieved total column of ozone ($O_3$) and tropospheric ozone vertical profile using the Optimal Estimation (OE) method based on the MAX-DOAS measurement at the Yonsei University in Seoul, Korea. The optical density fitting is carried out using the OE method to calculate ozone columns. The optical density between the MAX-DOAS data obtained by dividing the measured intensities for each viewing elevated angle by those at the zenith angle. The retrieved total columns of the ozone are 375.4 and 412.6 DU in the morning (08:13) and afternoon (17:55) on 23 May, 2017, respectively. In addition, under 10 km altitude, the $O_3$ vertical profile was retrieved with about 5% of retrieval uncertainty. However, above 10 km altitude, the $O_3$ vertical profile retrieval uncertainty was increased (>10%). The spectral fitting errors are 16.8% and 19.1% in the morning and afternoon, respectively. The method suggested in this present study can be useful to measure the total ozone column using the ground-based hyper-spectral UV sensors.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.791-802
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• 2015

The study was carried out to analyze vegetation structure of Mt. Eungbok located in Jochimryeong to Shinbaeryeong of the Baekdudaegan mountain range. The survey for 25 plots was conducted from April 2012 to August 2013 in the permanent plots using phytosociological analysis. As a result, the vegetations were classified into four vegetation units. In species composition, they were classified into Quercus mongolica community group divided into 2 community such as Ulmus laciniata community and Corylus sieboldiana var. mandshurica community, U. laciniata community was subdivided Rhododendron schlippenbachii group and Rubus crataegifolius group(into Viola albida subgroup, Rubus oldhamii subgroup). In terms of Importance values according to layer-specific and altitude of ridge, Q. mongolica was the highest importance value of tree layer and Acer pseudosieboldianum was highest importance value of sub tree layer. Therefore Q. mongolica and A. pseudosieboldianum could likely remain in the future of tree layer and sub tree layer respectively. Analysis of dominance most value of vegetation are on about 0.3. In ridge area was a species diversity result, vegetation unit 3 showed the highest value 0.974 and vegetation unit 1 showed the lowest value 0.725. Based on the interspecific association showed four types which were coincident with differential species and character species on the constancy table. Specially type I plant species were mostly differential species and the characteristic species, which appeared in the Rhododendron schlippenbachii community classified phytosociologically, and type III plant species were mostly the species appearing in the Corylus sieboldiana var. mandshurica community growing in the relatively.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.599-608
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• 2015

In this present study, we quantified the $SO_2$ effect on $O_3$ retrieval from the Ozone Monitoring Instrument (OMI) measurement. The difference between OMI-Total Ozone Mapping Spectrometer (TOMS) and OMI-Differential Optical Absorption Spectrometer (DOAS) total $O_3$ is calculated in high $SO_2$ volcanic plume on several volcanic eruptions (Anatahan, La Cumbre, Sierra Negra, and Piton) from 2005 through 2008. There is a certain correlation ($R{\geq}0.5$) between the difference and $OMI-SO_2$ in volcanic plumes and the significant difference close to 100 DU. The high $SO_2$ condition found to affect TOMS $O_3$ retrieval significantly due to a strong $SO_2$ absorption at the TOMS $O_3$ retrieval wavelengths. Besides, we calculated the difference against various $SO_2$ levels. There is the considerable difference (average = 32.9 DU; standard deviation = 13.5 DU) in the high $OMI-SO_2$ condition ($OMI-SO_2{\geq}7.0DU$). We also found that the rate of change in the difference per 1.0 DU change in middle troposphere (TRM) and upper troposphere and stratosphere (STL) $SO_2$ columns are 3.9 DU and 4.9 DU, respectively.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.133-143
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• 2017

The objective of this study is to examine whether citizens' expectations of policy impacts of the government's efforts to reduce overlap and duplication among its programs have any influence on citizens' policy attitude. Furthermore, this study examines whether the influence is differential and dependent on income class differences. The results suggest that 'reducing budget waste' bas a positive impact on policy attitude whereas 'enhancing work performance' bad no significant impact. And the results reveal that middle class bold a more negative view than upper class on the government's efforts. Concerning the moderating effect. income class differences weaken the positive relationship between 'reducing budget waste' and policy attitude as well the negative relationship between 'enhancing work performance' and policy attitude. The policy implication of this study is, to gain support from citizens for its overlap and duplication reduction policies, it is critical that the government should publicize that there exists a more of citizens benefitting from such policies.

• Tunnel and Underground Space
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• v.25 no.6
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• pp.527-533
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• 2015

This study performed an on-site demonstration of the topographic surveying technique at a large-scale open-pit limestone mine in Korea using a fixed-wing unmanned aerial vehicle (UAV, Drone, SenseFly eBee). 288 sheets of aerial photos were taken by an automatic flight for 30 minutes under conditions of 300 m altitude and 12 m/s speed. Except for 37 aerial photos in which no keypoint was detected, 251 aerial photos were utilized for data processing including correction and matching, then an orthomosaic image and digital surface model with 7 cm grid spacing could be generated. A comparison of the X, Y, Z-coordinates of 4 ground control points measured by differential global positioning system and those determined by fixed-wing UAV photogrammetry revealed that the root mean squared errors were around 15 cm. Because the fixed-wing UAV has relatively longer flight time and larger coverage area than rotary-wing UAVs, it can be effectively utilized in large-scale open-pit mines as a topographic surveying tool.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.281-289
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• 2016

Accurate prediction of the trajectory and time of a time-varying mass parachute system remains essential in the mission requiring a precision airdrop to the ground. In this study, we investigate the altitude-varying behavior of a cross-type parachute system designed to deliver a time-varying mass object like flare. The dynamics of the descending parachute system was analyzed based on the Runge-Kutta method of the ordinary differential system. The drag coefficients of the cross-type parachute and flare were calculated by a CFD code based on the incompressible Navier-Stokes equation. Finally, by using a simplified gust wind model in troposphere, the combined effects of gust wind and time-varying mass were examined in detail.

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.379-391
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• 2009

This study was carried out to classify forest vegetation structure of Mt. Munsu and Mt. Okseok from May to September in 2008 using phytosociological analysis methodology of Z-M school under the purpose of furnishing basic materials for rational and scientific forest management. Total of one hundred five study sites (quadrats) was investigated in the area. Quercus mongolica community group was divided into 5 communities such as Pinus densiflora for. erecta community, Hydrangea serrata for. acuminata community, Salix gracilistyla community, Pinus koraiensis community and Larix kaempferi community. Pinus densiflora for. erecta community was subdivided into Rhododendron micranthum group, Quercus variabilis group and Pinus densiflora for. erecta typical group. Hydrangea serrata for. acuminata community also into Ligularia fischeri group, Deutzia glabrata group (into Juglans mandshurica subgroup, Prunus maackii subgroup and Callicarpa japonica subgroup). Accordingly, the vegetation of the study areas could be described as 1 community group, 5 communities, 5 groups, and 3 subgroups and as 10 units in total. Classified vegetation units were highly correlated with altitude and topography. According the analysis of interspecific association, it was shown as three types which were coincident with differential species and character species on the constancy table.