• Journal of Environmental Impact Assessment
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• v.24 no.3
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• pp.278-286
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• 2015

Pilot scale system was designed to identify the growth and movement of algae, depending on environmental changes(retention time, nutrient concentration, etc) in Gangjeong-Goryeong Weir of the Nakdong River. Considering the stability of algal culture and easy observation of algal growth, pilot scale system was made of transparent acrylic material(3 sets of flexible cylindrical water tanks with 1 m diameter and 4 m height). Auxiliary equipments include light intercepter, water inflow device for different water depth and storage of reclaimed water. The retention time was 2 days(before construction of weir; treatment 1), 8 days(after construction of weir, 2013; treatment 2) and 30 days(2014; treatment 3). According to the water temperature of treatment 1 were similar by depth, treatment 3 showed a difference between the surface(0 m) and bottom(4 m) more than $3^{\circ}C$. DO, pH showed relatively high in the surface than the bottom. Nutrients showed eutrophic condition in all experiments. The Chlrophyll-a concentration of the treatment 1 showed a relatively lower value than the Chlrophyll-a concentration of the treatment 2 and 3. Therefore, the retention time was considered to influence the growth of phytoplankton.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.328-334
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• 2013

A greenhouse heating system to improve heat pump performance using inside and outside air of greenhouse as a heat source selectively and cut $CO_2$ enrichment costs by delay of greenhouse ventilation was developed. In this system, thermal storage modes divided into inside circulation mode using surplus solar energy and outside circulation mode using outside air heat. The thermal storage modes were designed to be switched mutually according to inside greenhouse temperature and six temperature values were input to control the heat pump operating, thermal storage mode switching and greenhouse heating automatically. Operating characteristics of this system were tested in a plastic greenhouse of non-ventilation condition. The results of test showed that the inside circulation mode began at about 11:00 and lasted for about 210 minutes and inside greenhouse temperature was maintained between $20{\sim}28^{\circ}C$ in spite of non-ventilation. System heating COP of the inside circulation mode in the daytime was 3.35, which was 36% and 25% higher than that of the outside circulation modes in the nighttime and daytime respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.610-616
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• 2012

All the countries in the world is currently facing the full scale of energy-climate era currently, and making strong energy policy that will lead to green growth of the future energy resources by utilizing renewable energy as the basis of entering the advanced country becomes the goal of development that satisfies the demand for energy in 21st century. Recently, ocean energy attracted the attention along with the necessity of developing renewable energy. Ocean energy is the one of most prominent recyclable and clean resources that has not been developed yet. So, it is highly required to develop good tidal current energy conversion system in coastal area. The inflow angle that acts against tidal current turbine, seabed effect and the change of efficiency along the occurrence of cavitation were investigated through the wake flow characteristics in this study. Power coefficient degradation by seabed effect did not appear in the condition of this calculation. Efficiency degradation appeared from above $10^{\circ}$ regarding inflow angle and power coefficient was calculated as lower by 7 % at $45^{\circ}$. Torque and power coefficient increased as inflow velocity rose, but power coefficient degradation appeared from above 3m/s when the cavitation happened. So, it was recognized that the larger inflow angle and occurrence of cavitation become the reason for power degradation through the flow characteristics.

• Journal of Digital Convergence
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• v.16 no.5
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• pp.43-53
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• 2018

Recently, public service for the improvement of quality of life and life support such as safety, aging, disaster, welfare, housing, economy, urban environment, traffic etc are actively developed based on open public data, and the spread of the network and the necessity of everyday life, smartphones are playing a role in providing public services. Currently, the development of science is changing the life expectancy of human beings and changing into social structure in which aged people become bigger due to various social conditions and low fertility and aging problems. However, the elderly who do not have easy access to information are very uncomfortable in dealing with mobile devices with very low accessibility and utilization of public services provided by mobile phones. Therefore, this study recategorizes the condition of the elderly presented in the previous study and identifies the problem through case analysis provided for the elderly. Also, we summarize the hierarchy of the core items of the existing interface design and derive it as an improvement index of the public service design for the improvement of the information accessibility of the elderly, and propose a design method to improve the utilization of the public service provided through the mobile device.

• Korean Journal of Environment and Ecology
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• v.11 no.1
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• pp.46-60
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• 1997

The purposes of this research are to select the appropriate kinds of landscape woody plants for afforestation artificial ground and to find out the way of developing planting-tree area of artificial ground through test planting and case study. The summary of the research is as follows; As a result of observing the state of trees' growth, trees on artificial grounds grow as well as, or even better than those on natural grounds. The kinds of trees which represent better growth states on artificial soil of rooftop test area are Thuja occidentalis, Prunus armericana var. ausu, Acer palmatum, Viburnum sargentii for. sterile, Buxus microphylla var. koreana, etc. In addition, soils than on natural soils. As a result of investigating the tree's growth state according to soil beds of artificial soils, shrubs don't represent distinct differences. They show that shrubs can be planted on 30cm soil bed. The rest of trees no differences according to the variation of soil beds, and they are in normal condition or have slight damage. This means that though arbor planting area of artificial ground is made 45~60cm, it is possible for trees to grow on it. In consequence of analyzing the cases on areas of landscaping artificial grounds, as the appropriate kinds of trees for afforestation artificial ground, Diospyros kaki, Hibiscus syriacus, Syringa dilatata, Magnolia kobus, Acer ginnala and cornus alba are selected in Capital region, and Nandina domestica, Taxus cuspidata, Ilex crenata, Viburnum awabuki, Aucuba japonica and Euonymus japonica are selected in southern region. In addition, Juniperus chinensis, Zelkova serrata, Juniperus chinensis var. kaizuka, etc. are selected regardless of regional character. In accordance with the state of soil it shows great difference, namely, fertilization once or more a year and irrigation for drought is advantageous to tree's growth. This research represents that it is necessary that standards related to landscaping artificial grounds are subdivided. In addition to it, the plan for revising related to regulation is drawn up.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.71-80
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• 2016

The fauna of freshwater fish and water chemistry characteristics were investigated from June, 2014 to October, 2014 at 10 sites in Taebaeksan Provincial Park. A total of 7 species under three families were collected from the survey sites and among them one endangered species - Koreocobitis naktongensis - was identified. The endemic species of Korea were 2 species: Koreocobitis naktongensis, Iksookimia koreensis. Dominant species was Rhynchocypris oxycephalus(89%) and subdominant species was Orthrias nudus(8.9%). Water quality including conductivity, turbidity, pH and total dissolved solids(TDS) varied largely depending on the sampling locations. Values of ambient conductivity and TDS were greater in the upstream than in the downstream, and seasonal variabilities were also higher in the upstream. The pH decreased towards the downstream, and especially showed a sharp decrease in S5. This phenomenon was evident due to a dilution by the influx in the acid mine drainage(AMD) of S4. Physical habit conditions, based on qualitative habitat evaluation index(QHEI) model, indicated a "Sub-optimal" condition(mean: 157.3; range: 78 ~ 194) in the Sodo stream watersheds.

• Korean Journal of Environment and Ecology
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• v.34 no.3
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• pp.198-206
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• 2020

The purpose of this study was to investigate the damage caused by rodents in the area around Seseokpyeongjeon in Jirisan National Park and identify suspected perpetrating species by analyzing rodent excrement found near the damaged trees. Damaged trees were surveyed regardless of species of trees in the exploration trail in the target site where visual observation was possible. Sequencing analysis of mitochondrial DNA Cyt-b was performed on rodent excrement around the damaged trees to identify the perpetrating species. A total of 52 trees were damaged by rodents, and they were all identified to be Korean Fir (Abies koreana) and were concentrated in places where Korean Fir formed communities with high density. A total of 40 Korean Fir over 1.5 meters high were surveyed, and only the affected branches, not the whole tree, were found to be withered in 39 of them. A total of 12 Korean Fir under 1.5 meters high were surveyed, and 7 of which were found to have been completely withered, indicating that relatively young trees were more vulnerable to withering. The genetic sequencing analysis of excrement confirmed that the species that perpetrated the Korean Fir was Craseomys regulus.

• Korean journal of applied entomology
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• v.43 no.2
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• pp.135-141
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• 2004

This study was carried out to review the distributional data of Dorcus hopei in Korea and to investigate ecological characteristics to develop a mass rearing technique of the species. The coupling period of the male and female was needed at least 2 weeks in condition of 6 months after emergence, and the optimal sex ratio for oviposition was 2♀：1♂. Eggs were laid singly, up to 27.3 per female. The pre-ovipostion period was average 147.3 days, egg-period was 15.6 days on the average, and oviposition period was at least 120 days. The optimum size of oviposition room was 55${\times}$40${\times}$35 cm with 3-4 oviposition-trees cut in size of 15${\times}$15 cm. Quercus acutissima was highly preferred for the oviposition. Developing period of each instar in the insectary (25$^{\circ}C$, 75％ R.H.. 16L：8D) was 24.1 days for the 1st instar,29.8 days for the 2nd, and 131.2 days for the 3rd instar, and 28.9 days for the pupa. The longevity of adults was longer than 35 months. The period of induced dormancy was needed at least 3-4 months.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.90-101
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• 2016

This study was initiated to develop an algorithm for traffic condition adaptive optimal traffic signal control for isolated intersections based on the vehicle trajectory data. The algorithm determines the optimal cycle length, phase lengths, phase sequences using the data collected under V2X communication environment every second. In addition, the algorithm utilizes a traditional feature of the actuated signal control, gap-out, using traditional detector systems to consider the mixture of normal vehicles and vehicles equipped with the V2X communication function. The performance of the algorithm was compared with that of the fixed signal timing plan which was optimized with Synchro under a microscopic traffic simulation-based test bed. As a result, the overall performance, including average delay, average stop delay, the number of stops, and average speed, are improved apparently. In addition, the amount of improvement get bigger as the traffic volume in the intersection as well as the number of vehicles equipped with the V2X communication function increase.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.107-116
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• 2017

When drilling operation is being performed, many physical and chemical changes are occurred near wellbore. To handle various changes of well condition and keep drilling process safe, additives of bulk, such as bentonite for increasing density of drilling mud, barite for increasing viscosity of drilling mud, polymer for chemical control, or surfactant, are added into drilling mud through a mud shear mixer. Because the achievement of the required material property through mud mixing system is essential to stabilize drilling system, it is of importance to analyze multi-phase flow during mud mixing process, which is directly related to increase mixing performance of the system and guarantee the safety of the whole drilling system. In this study, a series of liquid-solid flow simulation based on a computational fluid dynamics (CFD) are performed with comparing to solid concentration in experiment by Gilles et al. [2004] to understand the characteristics of liquid-solid mixing in a mud shear mixer. And then, the simulation-based design of shear mixer are carried out to improve mixing performance in a mud handling system.