• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.655-663
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• 2010

DUP (direct underside pressurization) is a device that can considerably increase lift, reduce take-off speed and minimize hump drag when a WIG effect vehicle takes off on the water surface. A 3-dimensional numerical investigation of a WIG effect vehicle with DUP is performed to analyze aerodynamic characteristics and the static height stability. The model vehicle, named Aircat, consists of a propeller in the middle of a fuselage, an air chamber under the fuselage, Lippisch-type wings and a large horizontal T-tail. The lift is mainly increased by the stagnation of the accelerated air coming into the air chamber through the channel in the middle of the fuselage. However, the accelerated air increases drag as well as reduces static height stability.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.244-249
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• 2015

High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

• The Microorganisms and Industry
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• v.10 no.1
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• pp.2-6
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• 1978

백신이란 학문의 원조는 고금 동서를 불문하고 영국의 Jenner라는 것은 우리가 잘아는 사실이다. 이것은 약 200년전의 일이며 그후 각종 전염병예방 백신이 개발되어 오늘날 우리인간은 예전ㅇ 비해 각종 전염병에 대해 큰 은혜를 받고 있는 셈이다.특히 1949년 미국의 Enders박사 일맥의 조직 배양의 개량법에 의한 바이러스의 대량 배양과 정제및 농축이 용이하게 된것은 백신생산 개발문제뿐만아니라 바이러스학과 전염병 예방학의 발전의 일대혁신을 가져왔으며 세균학에 있어서 Koch의 고형배제를 사용하여 많은 병원성세균의 발견을 하게된 것과 비슷한 느낌을 준다. Enders의 조직배양의 modern technique는 아직까지 원인불명인 여러 종류의 바이러스 전염병 병원체가 구명되었으며 지금도 계속 새로운 바이러스가 발견되고 있는 중이다. 그 대표적인 예를 들면 폴리오(Polio)를 중심으로 Coxsackie virus의 A및 B군과 ECHO virus등 장관계바이러스들의 발견과 그 체계적정비 그리고 Adeno virus를 위시한 호흡기계 바이러스들의 계속적인 발견과 그 실험실진단법의 확립등을 들수 있다. 한편 백신개발에 대한 확립 등을 들수있다. 한편 백신개발에 대한 발자취를 보면 폴리오를 위시하여 홍역(Measles)백신, 멈프스(Mumps)및 풍진 (Rubella virus) 백신등의 개발은 근래 선,후진국을 막론하고 이러한 전염병의 예방효과가 눈에 띠게 덕을 보고있는 것이다. 지금 세계적으로 많은 전염병의 병원체가 바이러스라는 것이 알려져 있고 또한 이에 대한 백신의 개발연구가 활발하게 진행되고 있다. 이번 기회에 바이러스백신의 전망이라는 제목을 가지고 논하게 된것을 기쁘게 생가하며 동시에 어려운 과제라고도 생각된다. 왜냐하면 아직 우리나라에서는 생산을 못하고 있는것이 많은데 그 전망을 말하기가 어려운 까닭이며 또한 제한된 지면에서 충분히 고찰하기는 어렵다. 우리나라에서 자주 거론되는 백신 및 종류에 국한하여 그 문제점과 앞으로의 전망을 고찰해 보기로 한다.

• The Journal of the Petrological Society of Korea
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• v.20 no.4
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• pp.243-250
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• 2011

This study considers the historical eruption record in 1702 from the volcanological point of view, which is presumed to have occurred from Mt. Baegdusan volcano. The minium volume of erupted materials is estimated to be $1.2km^3$ when calculated with an empirical formula using an isopach line obtained from two points 140 km away from the vent. The 1702 eruption was a paroxysmal one with VEI of 5. The historical record described a deposition of wind-modified fallout ash by movement of hot ash cloud. To prepare for the future eruption, we have to analyze historical literatures and understand characteristics of volcano.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.1
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• pp.3-9
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• 2010

Drainage density, defined as the degree to which a landscape is dissected by streams, is a fundamental property of natural terrain that reflect the comprehensive morphologic response of watershed. In this study the spatial variability of drainage density is analyzed by statistical approach to it and its plotting method is proposed. Overland flow length is confirmed to be a highly variable spatial factor from the result of statistical analysis. Distribution map of drainage density based on spatial autocorrelation length in this study would be a superior tool to the classical definition of drainage density.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1104-1111
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• 2009

In the low altitude, mission of the aircraft is restricted by a variety of threats such as anti-air missiles and terrain obstacles. Especially, aircraft have always a risk of ground collision near terrain. In this study, to effectively solve this problem, we developed the flight path generation algorithm that is considered the terrain avoidance. In this flight path generation algorithm, waypoints that should be passed by the UAV are selected first. The waypoints are located in the middle of the terrain obstacles. Then, physically meaningful waypoints sets are classified by Dijkstra algorithm. The optimal waypoint guidance law based on the optimal control theory is applied to produce trajectory candidates. And finally the minimum control energy trajectory is determined.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.331-331
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• 2022

수자원에서의 증발산량은 물의 손실에 해당하고 이는 국가의 수자원 계획 및 개발 등에 기본자료로 이용, 물 순환 과정의 규명, 물 수지 분석, 작물의 소비수량 산정 등 여러 분야에 활용되고 있다. 국내외적으로 이러한 증발산량을 측정하기 위해서 큰 노력을 수행하고 있으며, 측정기기의 고도화 발전으로 인해 에디공분산 방법을 활용한 증발산량 조사가 주목을 받고 있다. 국내에서도 수자원의 조사·계획 및 관리에 관한 법률 제9조(수문조사의 실시)에 따라 측정범위가 확대되고 있음에도 적절한 관측소 설치에 관한 연구가 부족한 실정이다. 본 연구에서는 적절한 증발산량 관측망을 설계하는 절차에 관해 연구를 진행하였으며, 기기적 측면과 환경적 측면으로 나누어 분석을 시행하였다. 우선 기기적 측면에서는 에디공분산 방법의 가정사항에 적합한 위치를 선정해야 하며 이는 충분한 풍속 및 난류 발생에 용이한 지점, 관측소가 설치 가능한 위치, 관측소 유지관리를 위한 접근성 및 안정성, 원거리 자료취득을 위한 통신망 등이 고려되어야 한다. 환경적 측면에서는 증발과 증산으로 나누어 고려할 수 있는데 증발은 지면의 특성을 고려한 대상 유역의 경사, 지형, 토성, 토양수분을 분류하였으며, 증산은 대상 유역의 식생, 피복, LAI(leaf area index)를 고려하였다. 결과적으로 관측망 선정을 위하여 기기적 측면, 환경적 측면을 고려하여 분석인자를 산정하였고 증발산량 관측소의 설치지점 선정기준을 마련하였으며 관측망 설계에 대한 정량적인 평가를 위한 기준을 제시하였다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.4
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• pp.299-311
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• 2020

This paper analyzes the distribution of water vapor pressure and relative humidity in complex terrains by collecting weather observation data at 6 locations in the valley in Jungdae-ri, Ganjeon-myeon, Gurye-gun, Jeolla South Province and 14 locations in Akyang-myeon, Hadong-gun, Gyeongsang South Province, which form a single drainage basin in rural and mountainous regions. Previously estimated water vapor pressure used in the early warning system for agrometeorological hazard and actual water vapor pressure arrived at using the temperature and humidity that were measured at the highest density (1.5 m above ground) at every hour in the valley of Jungdae-ri between 19 December 2014 and 23 November 2015 and in the valley of Akyang between 15 August 2012 and 18 August 2013 were compared. The altitude-specific gradient of the observed water vapor pressure varied with different hours of the day and the difference in water vapor pressure between high and low altitudes increased in the night. The hourly variations in the water vapor pressure in the weather stations of the valley of Akyang with various topographic and ground conditions were caused by factors other than altitude. From the observed data of the study area, a coefficient that adj usts the variation in the water vapor pressure according to the specific difference in altitude and estimates it closer to the actual measured level was derived. Relative humidity was simulated as water vapor pressure estimated against the saturated water vapor pressure, thus, confirming that errors were further reduced using the derived coefficient than with the previous method that was used in the early warning system.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.3
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• pp.340-350
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• 2023

This study analyzed the difficulty level of class on the seasonal change unit for 84 students at a university of education. The conclusions of this study are as follows. First, if we first present the four topics that make up the seasonal changes in elementary science, the subjects that have the greatest difficulty in teaching for prospective elementary school teachers are 'Why do seasonal changes occur?' (Teaching difficulty level 4.05), 'The sun changes depending on the season' What is the difference between the southern altitude and the length of day and night?' (difficulty level of class, 3.12), 'What is the relationship between the altitude of the sun, length of shadow, and temperature during the day?' (difficulty level of class, 2.85), 'How does the temperature change depending on the season?' (class difficulty level 2.80). As a result, in the elementary science season change unit, the class on the four topics 'Why do seasons change?', which is classified as a class topic that requires the concept of spatial perception, showed a higher level of class difficulty than other units. Second, in the seasonal change unit, various factors of class difficulty appeared depending on the class topic. When pre-service elementary school teachers look at the factors that make class difficult when teaching a lesson on seasonal changes in order of frequency, 42 (50%) said 'Experimental instruction for comparing the altitude of solar masculine according to the tilt of the axis of rotation', followed by 'Solar masculine'. 38 people (45%) answered 'Difficulty in explaining mid-high altitude and the length of day and night', 27 people (32%) answered 'Difficulty in explaining the concept of mid-high altitude', and 24 people (32%) answered 'Difficulty in explaining seasonal changes in the sun's position.' 29%), 20 people (24%) said 'Explain the reasonable reason why the height of the light should be adjusted when measuring the solar altitude', and 16 people (19%) said 'It is difficult to explain the reason for the discrepancy between the solar altitude and the maximum temperature'. ), 'difficulties in measuring sand (ground) temperature' were mentioned by 12 people (14%). Third, when analyzing the factors of class difficulty, there were more curriculum factors than teacher factors. In this context, the exploratory activities on 'Why do seasonal changes occur?', the fourth topic of the seasonal change unit in which elementary school pre-service teachers showed the greatest difficulty in teaching, need improvement in terms of the curriculum.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.106-111
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• 1987

The susceptibility of 8 chrysanthemum varieties to Apelenchoides ritzemabosi, Shuhonothikara and Sagakiku were resistant by 11.7% and 14.5% each infested leaf, Sinrokusiogio, Dangonanako and Sintoa were susceptible as above 50%, Gold wave and Tenju were modertae by 24 to 26%. Percentage of infested leaf was positively correlated with the number of epidermal hair but not with leaf area, leaf thickness, stomatal size, number of stomata and length of epidermal hair. In effect of watering method, Polyethylene film cover plot was lowest by 9.4%, next conventional watering plot by 50%, Conventional watering and spray plot was the highest by 62%. The infested leaf rate was closely related with a number of rainy days than the amount of rainfall. Effect of chemical soil treatment, Temik showed the lowest infested leaf rate by 5%. There was no significant difference between the chemicals except Temik, but these are markedly effective in compare to control.