• International Journal of Internet, Broadcasting and Communication
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• 제14권1호
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• pp.201-208
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• 2022

As around the world, ground and underground transportation capacity is reaching its limit, centering on urban areas. As urban traffic becomes congested, time and cost are astronomical, and environmental destruction caused by urban pollution is becoming increasingly serious. As a way to solve this problem, the means of flying over the air are in the spotlight as the next generation of future transportation, and the concept of urban air mobility (UAM, Urban Air Mobility) is defined as systematic planning. The development of an electric-powered vertical take-off (eVTOL) aircraft that obtains electric power through a battery using a personal aerial vehicle (PAV) as a means of transportation has accelerated. As the aircraft development of new technology aircraft in the evtol method is actively carried out, the need to prepare systems such as aircraft certification standards, pilot qualification systems, and qualification management is emerging. The Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA), which lead international standards, announced new special technical conditions and temporary regulations SCVTOL-01, respectively. However, the pilot qualification system for operating the uam aircraft has not yet been clearly announced. Therefore, this paper analyzes the recently announced FAA regulations and EASA regulations to identify differences and directions in perspectives on UAMs and study the existing vertical take-off and landing aircraft (VTOL) pilot qualification system to present directions for qualification classification.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.29-32
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• 2008

In this paper, we propose one unsupervised classification technique using the degree of polarization (DoP) and the co-polarized phase-difference (CPD) statistics, instead of the entropy and alpha. It is shown that the DoP is closely related to the entropy, and the CPD to the alpha. The DoP explains the feature how much the effect of multiple reflections is contained. Hence, the DoP could be used as an important factor for classifying classes. The CPD can also be computed from the measured Mueller matrix elements. For the smooth surface scattering, the CPD is about $0^{\circ}$, and for dihedral-type scattering, the CPD is about $180^{\circ}$. A DoP-CPD diagram with appropriate boundaries between six different classes is developed based on the SAR image. The classification results are compared with the existing Entropy-alpha diagram as well as the IPL-AirSAR polarimetric data. The technique may have capability to classify an SAR image into six major classes; a bare surface, a village, a crown-layer short vegetation canopy, a trunk-layer short vegetation canopy, a crown-layer forest, and a trunk-dominated forest. Based on the DoP and CPD analysis, a simple three-component decomposition technique was also proposed.

• 한국융합학회논문지
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• 제12권8호
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• pp.31-37
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• 2021

산업의 발전으로 도시화로 인해 건물의 규모가 커지면서, 건물의 공기 정화 및 쾌적한 실내 환경을 유지의 필요성 또한 증가하고 있다. 냉동 시스템의 모니터링 기술의 발전으로 건물 내에 발생하는 전력 소모량을 관리할 수 있게 되었다. 특히 상업용 건물에서 발생하는 전력 소모량 중 약 40%가 냉동 시스템에서 일어난다. 따라서 본 연구 냉동시스템 고장진단 알고리즘을 개발하기 위해서 냉동시스템의 구조를 이해하고, 냉동 시스템의 운영과정에서 발생하는 데이터를 수집 분석하여 다양한 유형과 심각도를 가지는 고장 상황을 조기에 신속하게 탐지 분류하고자 하였다. 특히 분류가 어려운 고장 유형들의 분류 정확도를 향상시키기 위하여 3단계 진단 및 분류 알고리즘을 개발하여 제안하였다. 다수의 실험과 초모수 (hyper parameter) 최적화 과정을 거쳐 각 단계에 적합한 분류 모형으로 SVM과 LGBM에 기반 한 모형을 제시하였다. 본 연구에서는 고장에 영향을 미치는 특성을 최대한 보존하면서, 선행연구에서 어려움을 겪었던 냉매 관련 고장을 포함한 모든 고장 유형을 우수한 결과로 도출하였다.

• 설비공학논문집
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• 제16권4호
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• pp.332-339
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• 2004

A technical analysis was conducted to predict the development trend for the highly efficient absorption type refrigeration system. The study was based on a submitted patent during January 1981 and December 2000 in Korea, Japan and America. The total number of extruded patents from the registered database was 24,822 and the filtering process makes the reduction of the data number to 3,510. Technical development of Japan for the absorption type refrigeration system is prominent compared to the other country due to approximately 75％ of the patents coming from Japan. When the patent is divided into two categories, the patent for component technology for the refrigeration system makes up 75％ and the refrigerating type technology 25％ of the patents. This shows technical development for the system component is advanced compared to the technology development for the system type. When the patents are classified by nationality of patent applicants, foreigners contribute up to 33％ of the patents in Korea. However, Japan's case shows the 99％ of the patents are invented by the Japanese. If the patents are classified to the International Patent Classification, most of the data for the absorption type refrigeration system belongs to IPC F25B.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.320-323
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• 2006

Temperature inversion may cause air pollution problems because air pollutants cannot be dissipated through vertical motion of the atmosphere and are accumulated near the surface. The air quality is worsen gradually if an inversion event lasts for a long time. An inversion event is defined as consecutive temperature profiles with occurrence of the temperature inversion condition. In this paper, temperature inversion events over three major cities on Taiwan are analyzed. They are measured by ground-based microwave radiometers installed in Taipei, Taichung, and Kaohsiung from 2002 to 2004 by the Environment Protection Administration (EPA) of Taiwan. Characteristics of temperature inversion events at the three cities are extracted using different classification methods.

• 한국국방경영분석학회지
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• 제37권1호
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• pp.147-159
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• 2011

Recently, the military service period has been shortened continuously. Meanwhile, more skilled airmen are needed as the complexity of weapon systems increase. This phenomenon could lead to a disastrous result such as deteriorating the level of the readiness and the fighting power. We suggest a method to improve recruit's maintenance capability rapidly by assigning airmen to jobs appropriate to their characteristics using Datamining methods (K-menas and CART). We focus on the assigning method for air force's air-munition maintenance airmen since they are requested more skilled than other airmen. Grouping airmen with k-means method and devising classification rule with CART algorithm, we found that airmen's proficiency arrival period could be shortened by 1.79 months when they are assigned in the suggested way.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.637-641
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• 2003

Abrasive powders were recovered from electrical industry sludge by simple physical separation for their recycling. The raw electrical industry sludge was filter pressed, dried, dispersed and then classified by air classifier at various conditions. The three kinds of particles with different particle size distribution were classified by controlling rotor speed and air volumes of the classifier. The recovered abrasive powders, which are classified at 5,000,9000 and 13,000 rpm of rotor speed, are almost same properties to raw pumice, garnet and rouge powders, respectively. The results of particle size analysis, X-ray diffraction and SEM observation show that the recovered powders can be reused as an abrasive powders.

• 환경영향평가
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• 제5권1호
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• pp.95-105
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• 1996

Meteorological Joint Frequency Function required indispensably in long-term air quality prediction models were discussed for practical application in Korea. The algorithm, proposed by Turner(l964), is processed with daily solar insolation and cloudiness and height basically using Pasquill's atmospheric stability classification method. In spite of its necessity and applicability, the computer program, called STAR(STability ARray), had some significant difficulties caused from the difference in meteorological data format between that of original U.S. version and Korean's. To cope with the problems, revised STAR program for Korean users were composed of followings; applicability in any site of Korea with regard to local solar angle modification; feasibility with both of data which observed by two classes of weather service centers; and examination on output format associated with prediction models which should be used.

• 한국대기환경학회지
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• 제9권4호
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• pp.278-287
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• 1993

In order to calssify smog type durnig the summer season in Seoul, air Quality and meterorological data were analyzed by multivariate analysis. Among 15 variables relating to visibility, 10 variables were selected by multiple regression analysis for clustering of smog types; total suspended particle, sulfur dioxide, ozone, ntrogen dioxide, total hydrocarbon, south-north wind component, ralative humidity, precipitable water, mixing height and air temperature. Somg types were grouped into three clusters using cubic clustering criterion and the mumbers of days in each cluster were contained 74, 28 and 16 days. Each cluster was seperated clearly by sulfur dioxide, precipitable water and air teperature. The first cluster was representative of high ozone concentration and prevailing meterological conditions for ozone formation. Therefore, visibility in the first cluster was considered to be affected by photochemical smog. The third cluster showed characteristics of sulphurous smog type due to the higher concentration of primary pollutant, based on the dry condition than that in another cluster. On the other hand, the characteristic of the second cluster was not relatively clear, but considered to be in an intermediate characteristic between photochemical smog and sulphurous smog type.

• 설비공학논문집
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• 제1권3호
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• pp.252-263
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• 1989

A system of conservation equations for steady, oscillatory and pulsating duct flows are solved analytically by linearizing non-linear convective terms. Analytical solutions of velocity profiles for these flows are obtained in the form of infinite series. The experimental study for the air flow in a square duct ($40mm{\times}40mm$ and 400 mm long) is carried out to measure velocity profiles and other parameters by using a hot-wire anemometer with data acquisition and processing system. Major characteristics of the flows such as the classification of flow patterns, determination of critical Reynolds number and velocity profiles is accomplished from the experismental results.