• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.111-118
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• 2022

An electro-mechanical actuator (EMA) is an actuator that combines an electric motor with a mechanical power transmission elements, and it is suitable for urban air mobility (UAM) in terms of design freedom and maintenance. In this paper, the author presents the research results of the EMA that controls the rotor blade pitch angle of UAM. The actuator is based on an inverted roller screw and controls the blade pitch angle through a two-bar linkage. The dynamic equations for the actuator alone and the blade pitching motion with actuator were derived. For the latter, the equivalent moment of inertia is variable depending on the link angle due to the two-bar linkage. The variations of the equivalent moments of inertia are analyzed and compared in terms of the nut motion and the blade pitch motion. For an example model, the variation of the equivalent moment of inertia of the former is smaller than the latter, so it is judged that the dynamic equations derived from the point of view of the nut motion is suitable for the controller design.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.309-315
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• 2021

The purpose of the article is to analyze the functioning of economic systems in the context of the development of their potential in a circular economy. It is determined that the functioning of economic systems to ensure their sustainability should meet modern challenges and provide for the formation of competitive institutional architecture, the introduction of structural and regulatory innovations, the transition to an innovative model of development. The specific principles of functioning of economic systems include openness, nonlinearity, multivectority, dynamism, emergence, uncertainty about the development of economic processes. It is substantiated that the linear nature of development and equilibrium are not dominant in the functioning of economic systems, and increasing the level of economic efficiency should go hand in hand with minimizing the activities of enterprises, which necessitates the use of circular economy. The main prerequisites for the transition to a circular economy are analyzed. It is determined that the basic concept of the circular economy involves the development of a system of production and consumption, which is based on processing, reuse, repair, product sharing, change of consumption patterns and new business models and systems. The main elements of the circular economy include: a closed cycle, the use of renewable energy sources, systems thinking. The correlation of the principles of sustainable development and the peculiarities of the application of the circular economy is analyzed. It is determined that the circular economy contrasts with the traditional linear economic model, which is based on the model of "take-do-consume-throw away". The advantages and disadvantages due to the use of the principles of circular economy are given. Based on the study, steps are identified to accelerate the transition from a linear economy to a circular economy.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1135-1145
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• 2022

Due to increase in concerns related to the climate change, state-wide promotion of the carbon neutrality has been in progress thus far. Smart City could be one of the measures as the initiative to mitigate the missions process. The primary purpose of Smart City can be summarized to be maximization of the social net-beneift to be returned for the local citizens and derivation of the optimal pattern of the energy consumption could belong to one of the elements included in the net-benefit. Currently, the energy consumption by the buildings has been determined to be responsible for the greatest consumption among the sectors considered to be energy-intensive. Moreover, considering the fact that the consumption by operations of HVAC is responsible for nearly 40% in the commercial buildings, it is virtually not possible to optimize schedules for the energy consumption with considerable deliverables from the perspective of the urban planners. Thus, the methods to implement the optimal schedules for the HVAC commissioned with the OHUs were concluded to be the suitable candidate resources for the simulation by EnergyPlus capable of monitoring the thermal changes in each subject space in the present research.

• International Journal of High-Rise Buildings
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• v.12 no.1
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• pp.93-105
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• 2023

Seismic isolation and vibration control techniques have been developed and put into practical use by challenging researchers and engineers worldwide since the latter half of the 20th century, and after more than 40 years, they are now used in thousands of buildings, private residences, highways in many seismic areas in the world. Seismic isolation and vibration control structures can keep the structures undamaged even in a major earthquake and realize continuous occupancy. This performance has come to be recognized not only by engineers but also by ordinary people, becoming indispensable for the formation of a resilient society. However, the dynamic characteristics of seismically isolated bearings, the key elements, are highly dependent on the size effect and rate-of-loading, especially under extreme loading conditions. Therefore, confirming the actual properties and performance of these bearings with full-scale specimens under prescribed dynamic loading protocols is essential. The number of testing facilities with such capacity is still limited and even though the existing labs in the US, China, Taiwan, Italy, etc. are conducting these tests, their dynamic loading test setups are subjected to friction generated by the large vertical loads and inertial force of the heavy table which affect the accuracy of measured forces. To solve this problem, the authors have proposed a direct reaction force measuring system that can eliminate the effects of friction and inertia forces, and a seismic isolation testing facility with the proposed system (E-isolation) will be completed on March 2023 in Japan. This test facility is designed to conduct not only dynamic loading tests of seismic isolation bearings and dampers but also to perform hybrid simulations of seismically isolated structures. In this paper, design details and the realization of this system into an actual dynamic testing facility are presented and the outcomes are discussed.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.1
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• pp.23-39
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• 2023

Due to the recent population decrease and urban decline, it has become increasingly important to induce qualitative changes in the city itself and create a differentiated development model. Local culture, based on its uniqueness and diversity, generates the expansion and ripple effect of various contents through creative utilization. In this study, we examine a new local content approach called "town-stay (village hotel)" that develops cultural content and creates a place-making in terms of creating a sustainable ecosystem with cultural vitality. While the uniqueness and creativity of individual content can make a region's attractiveness stand out, we have seen in the case of small-sized cities in Korea and Japan that content elements (place, story, people) can be materialized into area-level content called town-stay(village hotel). The local contents are densely presented in a specific area to increase visibility and expand into a variety of content that reveals regional connections. Local creators, who are the core actors, understand locality, induce active activities, and pursue sustainable development that promotes not only economic value but also community solidarity.

• Korean Journal of Environment and Ecology
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• v.34 no.5
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• pp.491-499
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• 2020

Increasing impervious surfaces can cause various physical and mental illnesses as well as further problems like deterioration of the thermal environment and disconnection of the water circulation system in the downtown area. This study is intended to suggest baseline data for the future creation or remodelation of large-scaled urban parks in consideration of human health on the aspect of climate by analyzing air ions condition and correlation analysis between air ions and meteorological elements depending on distances from the center in the urban park. The study site was divided into four types by distances from the center of Olympic Park in Songpa-gu, Seoul, then classified as A and B. After selecting 80 points to record, land coverage and vegetation status were investigated, and then meteorological elements and air ions were measured. First, the green space rate by section is A section Center (90%)> Inner (70%)> Outer-inner (10%) = Outer (10%), B section Center (100%)> Inner (60%)> Outer- In order of inner (30%)> Outer (0%). Second, for weather factors, the temperature was analyzed by Outer (24.18℃) > Outer-inner (22.90℃) > Inner (22.43℃) > Center (21.719℃). For relative humidity, center (46.49%) > Inner (43.36%) > Outer-inner (42.41%) > Outer (38.53%) was analyzed. Third, In the case of cations in the air ions, Outer(435.71ea/㎤) > Outer-inner(415.16ea/㎤) > Inner (389.46ea/㎤) > Center (352.64ea/㎤). In the case of negative ions, Center (569.72ea/㎤) > Inner (499.83ea/㎤) > Outer-inner(410.58ea/㎤) > Outer (292.02ea/㎤). It was analyzed to increase toward Center, and analyzed to decrease with increasing distance from road. For the Air ion index, it was analyzed as Center (1.67) > Inner (1.31) > Outer-inner (1.08) > Outer (0.71). Negative irons was analyzed to increase when its measuring points close to the center and decrease with shortening distance to the road. Fourth, as a result of correlation analysis, positive(+) correlation is negative ions and ion index. These were measured to increase as the recording points closing to the center of the park from the road. The negative(-) correlation is temperature, solar radiation, and positive ions. These increased as getting closer to the road.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.266-279
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• 2014

For the evaluation of roadway safety, diverse methods, including before-after studies, simple comparison using historic traffic accident data, methods based on experts' opinion or literature, have been applied. Especially, many research efforts have developed traffic accident prediction models in order to identify critical elements causing accidents and evaluate the level of safety. A traffic accident prediction model must secure predictability and transferability. By acquiring the predictability, the model can increase the accuracy in predicting the frequency of accidents qualitatively and quantitatively. By guaranteeing the transferability, the model can be used for other locations with acceptable accuracy. To this end, traffic accident prediction models using non-linear regression, artificial neural network, and structural equation were developed in this study. The predictability and transferability of three models were compared using a model development data set collected from 90 signalized intersections and a model validation data set from other 33 signalized intersections based on mean absolute deviation and mean squared prediction error. As a result of the comparison using the model development data set, the artificial neural network showed the highest predictability. However, the non-linear regression model was found out to be most appropriate in the comparison using the model validation data set. Conclusively, the artificial neural network has a strong ability in representing the relationship between the frequency of traffic accidents and traffic and road design elements. However, the predictability of the artificial neural network significantly decreased when the artificial neural network was applied to a new data which was not used in the model developing.

• Journal of Korean Society of Forest Science
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• v.88 no.4
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• pp.510-522
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• 1999

The air pollutants ; $SO_2$, $SO{_4}^{-2}$, $NO{_3}^-$, $Cl^-$ are absorbed into soils through falling with dusts and rain from the atmosphere. The sources of heavy metal contaminants in the environments are agricultural and horticultural materials, sewage sludges, fossil fuel combustion, metallurgical industries, electronics and waste disposal etc.. The soils and hydrosphere can be polluted on the way of the circulation of these heavy metals. Studied pollutant anions are $SO{_4}^{-2}$, $NO{_3}^-$ and $Cl^-$ and heavy metals are Se, Mo, Zn, Cd, Pb, Mn, Cr, Co, V, As, Cu and Ni which are the elements to be concerned with the essentials for plants, with animal and human health. This study is with the aim of selecting the species of roadside trees and green space trees which have excellent absorption of air pollutants and heavy metals from the atmosphere and the soils in the urban area. Two areas are designated to carry out this study : urban area ; Kwangju city and rural area ; the yard of Forest Environment Institute of Chollanam-do, at Sanje-ri, Sampo-myum, Naju city, Chollanam-do (23km away from Kwangju). This study is carried out to understand the movement of anions and heavy metals from the soils to the trees in both areas, the absorption of anions and heavy metals from atmosphere into leaves and the amounts of anions and heavy metals in leaves and fine roots(< 1mm dia.) of roadside trees and green space trees in Kwangju and trees in the yard of Forest Environment Institute of Chollanam-do. The tree species selected for this study in both areas are Ginkgo biloba, Quercus acutissima, Cedrus deodara, Platanus occidentalis, Robinia pseudoacacia, Alnus japonica. Metasequoia glyptostroboides. Zekova serrata. Prunus serrulata var. spontanea, and Pinus densiflora. The results of the study are as follows : 1. $SO{_4}^{-2}$, $NO{_3}^-$ and $Cl^-$ concentrations are higher in the soils of the urban area than in those of the rural area, and $NO{_3}^-$ and $SO{_4}^{-2}$ are higher in the leaves than in the roots due to the absorption of the these pollutants through the stomata. 2. Ginkgo biloba, Robinia pseudoacacia. Zekova serrata, Quercus acutissima, and Platanus occidentalis can be adequated to the roadside trees and the environmental trees due to their good absorption of $NO{_3}^-$ and $SO{_4}^{-2}$. 3. Heavy metals in the soils of both areas are in the order of Mn > Zn > V > Cr > Pb > Ni > Cu > Mo> Cd, and in the leaves and roots of the trees in the both areas are in the order of Mn>Zn>Cr>Cu>V>Ni. Both orders are similar ones except V. There are more in the urban soils than in the rural soils in amount of Mn, Zn, Pb, V, Cu. 4. It is supposed that there is no antagonism between Mn and Zn in this study. 5. Se, Co and As are not detected in the soils, the leaves and the roots in both areas. Sn, Mo, Cd and Pb are also not detected in the leaves and roots in spite of considerable amount in the soils of both areas.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.3
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• pp.106-115
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• 2011

This study, based on (edited in 18th century), analysed the landscape system and cultural landscape elements of Yuhoidang(Hageowon 何去園) Garden in Musu-dong, Daejeon, and the findings are as in the following. YuHoidang(Gwon Yijin 權以鎭) managed Hageowon Garden in Musu-dong, located on the southern branch of Mt. Bomun, to realize his utopia. The completion of Hageowon Garden was only possible due to his installation of a variety of facilities in family gravesite on the hill behind his house: Shimyoso(Samgeunjeongsa 三近精舍, in 1707), Naboji(納汚池, in 1713), Banhwanwon(in 1714) and expended exterior space(in 1727). With regard to the landscape system of the village, the main range of mountains consists of Mt. Daedun, Mt. Odae and Mt. Bomun. The main high mountain of the three is Mt. Bomun, where 'Blue Dragon' hill branches off on the east side(Eungbong), 'White Tiger' in the west(Cheongeun and Sajeong) and Ansan(inner mountain) in the south. The landscape system is featured by 'mountains in back and rivers in front'. The river in the south-west, with its source in Mt. Juryun is called as the 'Stream of outer perfect spot', while the 'Stream of inner perfect spot' rises from Eungbong, passing through the east part of the village into the south-western direction. Banhwanwon Garden(盤桓園) was created with the stream in the east and natural bedrocks, and its landscape elements includes Naboji, Hwalsudam, Gosudae, Sumi Waterfall, Dogyeong(path of peach trees), Odeeokdae(platform with persimmon trees), Maeryong(Japanese apricot tree), springs and observatories. An expanded version of Banhwanwon was Hageowon garden, where a series of 'water-trees-stone' including streams, four ponds, five observation platforms, three bamboo forests and Chukgyeongwon(縮景園) of an artificial hill gives the origin forest a scenic atmosphere. When it comes to semantics landscape elements, there are (1) Yuhoidang to cherish the memory of a deceased parents, (2) Naboji for family unification, (3) Gosudae to keep fidelity, (4) Odeokdae to collect virtue and wisdom, (5) Sumi Waterfall to aspire to be a man of noble character, (6) Yocheondae for auspicious life, (7) Sumanheon and Gigungjae to be in pursuit of hermitic life, (8) Hwalsudam for development of family and study, (9) Mongjeong to repay favor of ancestors, (10) Seokgasan, a symbol of secluded life, (11) Hageowon to enjoy guarding graves in retired life. The spatial composition of Hageowon was realized through (1) Yuhoidang's inside gardens(Naboji, Jucheondang, Odeokdae, Dogyeong, Back yard garden and others) (2) Sumanheon(收漫軒) Byeolup or Yuhoidang's back yard gardens (Seokyeonji, Yocheondae, Sumanheon, Baegyeongdae, Amseokwon and others) (3) Chukgyeongwon of the artificial hill(which is also the east garden of Sumanheon, being composed of Hwalsudam, Sumi Waterfall and Gasan or 12 mountaintops) (4) the scenic spots for unifying Confucianism, Buddhism and Taoism are Cemetry garden in the back hill of the village, the temple of Yeogyeongam, Sansinkak(ancestral ritual place of folk religion) and Geoeopjae(family school). On top of that, Chagyeongwon Garden(借景園) commands a panoramic distant view of nature's changing beauty through the seasons.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.857-874
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• 1998

The objective of this study is to collect the opinions on the present condition and the improvement directions of urban health centers from and to make a comparison. Samples were drawn from the various sources of a district in seoul. 53 persons involved in district health's administration(the Members of a District Parliament, the senior officials of a District office, village chief) and 84 health center workers were surveyed with anonymous postal questionaires and 427 district private medical personnels with postal questionaires and 625 users of a health center with direct questionaires, from November 18 to 25, 1996. Additionally, 12,151 households were surveyed with self-reported questionaires including priorities on special district health services of health center, from September 1 to 7, 1996. The major findings were as follows : 1) Although the persons involved in district health administration tend to put lower priority on health service over other community activities, they well acknowledged the importance of health center. But health center workers strongly acknowledged the importance of both health service and heath center. 2) As to the level of human resoureces, equipments and ammenities of Health Center commpared with private medical institute, the persons involved in district health's administration and health center workers responded that health center was higher in following order : 54.9%, 41.6%, 36.5% and 88.0%, 80.7%, 44.1%. 3) Concerning the priorities of health center's improvement, the persons involved in district health's administration replied in the order of reinforcement of proffesional health workers (43.3%), improvement of equipments and ammenities(28.3%), and the health center workers replied in the order of reconstruction of organization(24.1%), public health education and promotion(22.8%), reinforcement of proffesional health workers(21.0%). 4) Both the persons involved in district health's administration and health center workers replied that Ministry Health and Welfare, District office, health center were essential as the most critical organizations in the activation of Health Center's Function. 5) Persons involved in district health's administration and health center workers chose, as the most important health center's Function, medical treatment and prevention of infectious disease, and prevention of acute and chrone disease control and special district health service, respectively. Both Groups replied that fammily planning and parasite control are no longer in need. 6) As the future health service requiring reinforcement, every human resources parties considered health conselling, health line, sex education as the most imortant elements in public health education. Concerning the reinforement of other health services such as medical checkup and visiting nurses, every human resources parties showed more than 80% approval rate, but for oriental medical care service, the private medical personels showed relatively low approval rate(52.9%). Therefore the planning for reinforcement of health center's function requires the reflection of human resources party's opinion and the implication of system which can control and combine the differences in party's opinions.