• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.481-487
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• 2023

Recently, interest in UAM (Urban Air Mobility) has surged as a critical solution to urban traffic congestion and air pollution issues. However, efficient UAM operation requires accurate 3D Point Cloud data processing, particularly in separating the ground and objects. This paper proposes and validates a method for effectively separating ground and objects in a UAM environment, taking into account its dynamic and complex characteristics. Our approach combines attitude information from MEMS sensors with ground plane estimation using RANSAC, allowing for ground/object separation that isless affected by GPS errors. Simulation results demonstrate that this method effectively operates in UAM settings, marking a significant step toward enhancing safety and efficiency in urban air mobility. Future research will focus on improving the accuracy of this algorithm, evaluating its performance in various UAM scenarios, and proceeding with actual drone tests.

• Journal of the Daesoon Academy of Sciences
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• v.32
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• pp.237-267
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• 2019

The article considers the problems of envisaging a paradise on earth, with special reference to Jehovah's Witnesses. After an explanation of their relationship to the Christian Protestant tradition, particularly Adventism and American fundamentalism, some key doctrines of the Watch Tower organisation are identified, with particular reference to their belief in a coming earthly paradise. Jehovah's Witnesses are a restorationist movement, seeking a restored paradise on earth, and endeavouring to restore authentic Christianity in what they take to be its original form. Discussion is given to the possibility of physical accommodation on the earth, the position of animals, family life, language, and technology. Finally, brief comparison is made with the expected paradise of the Daesoon Jinrihoe, which is based on a radically different worldview. It is concluded that such differences help to explain why Jehovah's Witnesses have limited success in Korea, as compared with indigenous Korean new religions such as Daesoon Jinrihoe.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.655-658
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• 2020

최근 IT 기술의 발달로 태블릿, 스마트폰과 같은 다양한 디바이스로 손쉽게 음악을 감상할 수 있다. 하지만 최근 이런 기술 발달과는 다르게 사용자가 원하는 음악을 검색하는 방법은 고전적인 형태에서 벗어나지 않고 있다. 기존 음악 검색 방법은 텍스트 기반, 내용 기반, 소비자 감성 기반의 음악 추천 검색 방법이 있으며 저장된 메타 데이터를 이용하여 사용자의 질의에 대한 결과만 제공할 뿐 사용자의 경험 정보를 고려하지 않는다. 그리고 기존 플랫폼들은 사용자가 최근 많이 들은 가수, 장르, 분위기를 종합하여 사용자에게 어울리는 음악을 추천을 할 뿐 사용자의 경험정보를 고려하여 음악을 추천하지는 않는다. 본 논문에서는 사용자의 경험 정보를 활용하여 사용자 맞춤형 음악 추천 시스템을 제안한다. 본 시스템은 사용자의 현재 기분 정보, 주변 날씨 정보 등을 입력 받는다. 이후, 경험 정보를 기반으로 결정 트리를 통해 사용자 요구 기반의 음악 추천 시스템을 구축하였다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.81-88
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• 2023

SHM (Structural Health Monitoring) technique for monitoring aircraft structural health and damage, EHM (Engine Health Monitoring) for monitoring aircraft engine performance, and APM (Application Performance Management) is used for each function. APMS (Airplane Performance Monitoring System) is a program that comprehensively applies these techniques to identify the difference between the performance manual provided by the manufacturer and the actual fuel mileage of the aircraft and reflect it in the flight plan. The main purpose of using APMS is to understand the performance of each aircraft, to plan and execute flights in an optimal way, and consequently to reduce fuel consumption. First, it is to check the fuel efficiency trend of each aircraft, check the correlation between the maintenance work performed and the fuel mileage, find the cause of the fuel mileage increase/decrease, and take appropriate measures in response. Second, it is to find the cause of fuel mileage degradation in detail by checking the trends by engine performance and fuselage drag effect. Third, the APMS is to be used in making maintenance work decisions. Through APMS, aircraft with below average fuel mileage are identified, the cause of fuel mileage degradation is identified, and appropriate corrective actions are determined. Fourth, APMS data is used to analyze the economic analysis of equipment installation investment. The cost can be easily calculated as the equipment installation cost, but the benefit is fuel efficiency improvement, and the only way to check this is the manufacturer's theory. Therefore, verifying the effect after installation and verifying the economic analysis is to secure the appropriateness of the investment. Through this, proper investment in fuel efficiency improvement equipment will be made, and fuel efficiency will be improved.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.35-50
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• 1999

The relationship between floristic composition and soil environmental conditions was investigated in the forest vegetation of Mt. Paekun. The forest vegetation unit of Mt. Paekun was divided into six plant communities by Zurich-Montpellier method, such as Quercus mongelica community (Typical subcommunity, Rhododendron schlippenbaohii subcommunity), Q. variabilis community, Fraxinus rhynchophylla community, Pinus densiflora community, Larix Eeptolepis community and Pinus koraiensis community. Q. mongolica community group was distributed at the altitude over 500 meter, Q. variabilis and P. densiflora communities appeared on the southwestern slope at the altitudes of 600 ~ 700 m and 290 ~ 700 m. However, L. leptolepis and P. koraiensis plantation were distributed at lower altitude, on hillside or around homestead. The DBH class distribution of dominant species in each community showed that Q. mongolica had 10.9 individuals/a at 6~10 cm class, Q. variabilis 2.5 individuals/a at 11~15 cm class, P. densiflora 1.8 individuals/a at 26~30 cm class, F. rhynchophylla 3.3 individuals/a at 2~5 cm class, and L. leptolepis 5.9 individuals/a at 11~ 15 cm class. Q. mongolica and Q. variabilis communities showed a stable bell-shaped pattern of distribution. The contents of organic matters and soil water, and cation exchange capacity of the soil increased, and the pH decreased as the altitude gets higher increased altitude at the each communities. The contents of the soil water and organic matters of the forest soil collected in Q. mongolica community were in the 17.81% to 51.20% and 5.51% to 14.90%, respectively. These tendency is similar to the contents of N, P and K, but those of Ca, Mg, and CEC was lower than in other communities. Cation exchange capacity was suspected to be correlated to the pH. The hypothetical successional sere of the forest vegetation of Mt. Paekun is as follows: Pinus densiflora community longrightarrowQ. variabilis community longrightarrowQ. mongolica community.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.37 no.3
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• pp.13-21
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• 2019

The purpose of this study is to understand the actual conditions of Seolleung and Jeongneung historical cultural landscape forests of Joseon Royal Tombs and to prepare systematic preservation and management plans, and the results of the study are as follows. First, in the current situation, vegetation is dominated by Quercus aliena and Pinus densiflora, and it is distributed as Quercus aliena community 21.22%, Pinus densiflora community 21.22% and Pinus densiflora afforestation 3.69%. The main vegetation communities are Pinus densiflora community, Quercus aliena community, Alnus japonica community, Pinus densiflora afforestation, and Pinus koraiensis afforestation. Second, in the measuring of Diameter of Basal Height in eight quadrat, the main species were Pinus densiflora, Quercus aliena and Alnus japonica and the maximum Distribution of Diameter of Basal Height was 20-25cm of Pinus densiflora, 25-30cm of Quercus aliena, and 25-30cm of Alnus japonica. Third, the forest is located between King and Queen's royal tombs in Seolleung, which is not suitable for the form of the tombs. In Jeongneung, the narrow space of the ceremony area shows an unfavorable environment for the formation of pine forests, and the pine forests on the left and right have a different heights that hinders the visual landscape. Fourth, as a management plan for the forests, stray pine trees, which are exotic species, are removed and pine forests are formed along the ridges. After removing the forest between the King and Queen's royal tombs of Seolleung, grass is formed, and the height of the pine forest on the left and right of Jeongneung is adjusted, and pines near the Gokjang are continuously monitored. Visually heterogeneous trees are arranged boldly, the boundary is adjusted to harmonize with the surrounding deciduous trees and maintains a buffer space of about 10m. This study is expected to provide important implications for Joseon Royal Tombs and in the future, the actual conditions of each Joseon Royal Tombs should be understood and appropriate management plans should be prepared.

• Journal of Korean Society of Forest Science
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• v.77 no.3
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• pp.303-314
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• 1988

Tong-ri beach has not enough vegetation to be enjoyed by the sea bathers and to be satisfied with preventing the disaster-damages, but mixed forest near the beach can work its funtions and the old forest of Pirus thunbergii $P_{ARL}$. near the beach do a Little. Therefore it is very urgent to plant more trees near the beach for bathers and disaster-damage prevention. This study was carried out for planning an afforestation, with reporting upon the crown amounts and soil properties of disaster-damage prevention forests of P. thunbergii $P_{ARL}$. planted on the coast sand dunes in 1970 and 1976, and with reporting upon the valuation on soil properties of the lands near the beach in order to set the afforestation site. The results are as follows : 1. In disaster-damage prevention forests, crown surface area and crown volume became increasingly greater in proportion to the height. To D.B.H., crown volume also became increasingly greater in proportion, but crown surface area was directly proportional. 2. In comparison to sail characteristics of sand dune, those of the forests were in large quantity in OM, T-N and avail. $SiO_2$, and almost in the same in avail. $P_2O_5$, but in small quantity in exchangeable canons : K, Ca, Mg and Na. 3. EC, Cl and pH were in small value in the forest soils, but CEC was in large value in those soils. 4. Above facts showed that the forests fulfill their functions for preventing disaster-damages and improve their soil properties. 5. The forests have naturally been thinned up to 34% in 17 years and 39% in 11 years, and one can easily pass through the forest(planted in 1970), because of its sufficient clear-length(2.71m) and its space to pass. 6. A plan for afforestation was oracle nut after judging several sites by the evaluation on the soil properties and considering the best relaxation and the prevention of the various disaster-damages upon which were reported in the last issue. 7. Afforestation should be kept for maintaining its appropriate density for best relaxation and disaster-damage prevention.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.493-501
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• 2007

The membrane pilot plant has being operated in the Hyeondo pumping station to find the optimal operation technique of Gong-Ju membrane water treatment plant (WTP) which is constructing in $250m^3/d$ scale. The pilot plant was consisted of two trains which can treat $30,000m^3/d$ per train. First train was operated for one year under the condition of flux $1m^3/m^2{\cdot}d$ while the effects of flux variation and addition of powdered activated carbon(PAC) were evaluated in second train. The turbidity of membrane product water of first train which is operated on Flux $1m^3/m^2{\cdot}d$ was always below 0.05 NTU regardless of raw water turbidity. And also, the trance-membrane pressure(TMP) was maintained at $0.3{\sim}0.5kgf/cm^2$ for about 9 months and increased rapidly to $1.8kgf/cm^2$ which is maximum operating TMP. However, TMP was rapidly increased to $1.8kgf/cm^2$ within 2 months as flux was increased from 1 to $2m^3/m^2{\cdot}d$, especially, within 10 days under high turbidity(30~50NTU). This reault means that if Gongju membrane WTP is operated in flux $1m^3/m^2{\cdot}d$, chemical cleaning period can be maintained over 6 months. Only 10% of dissolved organic carbon (DOC) was removed in membrane process while the removal efficiencies of manganese and iron were 60% and 77% respectively. However, because only solid manganese and iron were removed in membrane process, an additional process for treating soluble manganese is required if souble manganese is high in raw water. 70% of 70ng/L 2-MIB which is causing taste & odor was removed in powdered activated carbon (PAC) tank with 50mg/L PAC which is design concentration of Gongju WTP. In addition, TMP was reduced with addition of 50mg/L PAC regardless of flux. Because TMP was not influenced even if 100mg/L PAC was added, the high taste and odor problem can be controled by additional injection of PAC.

• Membrane Journal
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• v.22 no.2
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• pp.135-141
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• 2012

This study was carried out to find the optimum coagulation conditions for ceramic microfiltration process of Y water treatment plant. When pH of raw water from Y Dam was adjusted to 7, the efficiency of coagulation was the best and the optimun dosage of coagulant was 3 mg/L(as $Al_2O_3$) for turbidity of raw water less then 10 NTU in Jar test. In mini module test, the decay rate of specific flux was the lowest when PAC (poly Aluminum Chloride) was used among coagulants and pH was adjusted to 7. The decay rate of specific flux for raw water turbidity of 10~30 NTU was greatly decreased with increase of dosage of coagulant (PAC) while the rate was not significantly decreased for turbidity more than 50 NTU. In conclusion, the optimum dosage of PAC (11% as $Al_2O_3$) was 30 and 50 mg/L for raw water turbidity of less than 10 NTU and more than 50 NTU, respectively. The dosage of PAC should be increased linearly 30 to 50 mg/L depending on raw water turbidity of 10 to 50 NTU.

• The Korean Journal of Ecology
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• v.28 no.4
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• pp.223-230
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• 2005

The vegetation of Bijin and Yongcho Islets was investigated from February 1, 2000 to March 30, 2002, and forest structure was constructed. Vascular plants of this area consisted of 12 forms, 59 varieties, 476 species, 352 genera, 112 families and 37 orders. Among them, 37 species (6.8% out of the total 547 taxa) of evergreen broad leaved trees, 36 species (6.6% out of the total 547 taxa and 19.7% out of the total naturalized plants in Korea) of naturalized plants, 6 species of endemic plants and 41 species of cultivated plants were observed. Rare and endangered plants include 1 taxa: Crypsinus hastatus ('98-4). The vegetation in this study area was classified into 9 communities (Pinus thunbergii, Castanopsis cuspidata var thunbergii Camellia japonica, Neolitsea sericea, Machilus thunbergii, Quercus variabilis, Carpinus coreana, Platycarya strobilacea, Miscanthus sinensis var. purpurascens) and 1 afforestation (Alnus firma).