• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.552-557
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• 2015

Recent performed by recognizing a user's location, various services have been tailored focus on short-range wireless communication technology. A beacon in which is attracting attention as next-generation technology. Beacon is a terminal by utilizing the frequency of the non-audible area can not be bluetooth and human sending and receiving terminals and information, Apple recently iBeacon like a low-power Bluetooth (BLE; bluetooth low energy) based beacon showing a tendency to rise into the mainstream there. Services using a beacon is basically installs the terminal in a certain place indoor. It is characterized by providing the user the services to catch the user's position, even automatically take a separate action. Various types of location-based service provided by the target interior space began to attract attention. A variety of location-based services are provided in the interior space in order to be successfully deployed and provide guidance to the interior space, the movement route and the like are essentially required to build various types of information. In this paper, for efficient indoor positioning by varying the signal strength of the beacon in such areas were measured and analyzed.

• Environmental and Resource Economics Review
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• v.27 no.2
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• pp.261-286
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• 2018

This paper evaluated the economic feasibility of the life extension of Kori unit 1 and Wolsong unit 1 according to the types of the nuclear power plants (NPPs) and the life extension period comparing to the levelized costs of energy (LCOE) of the new NPPs, coal-fired plants (CFPs), and combined cycle gas turbine (CCGTs) which proposed in the $7^{th}$ Basic Plan for Electricity Supply and Demand. The economic feasibility of the life extension of NPPs using LCOE method is affected by the types of NPPs, lifetime extension periods, discount rate, and capacity factor. According to the analysis results, the pressurized light water reactor (PWR) is more economical than the pressurized heavy water reactor (PHWR). Comparing the economical efficiency between the life extension of NPPs and other alternatives, the operation of the PWR for 20 years is more economical than the one of new NPPs and CFPs. However, 20 years of life extension of PHWR is more economical than the CCGTs, but less economical than new NPPs and CFPs. In summary, the 20 years of life extension of the NPPs seems to be more, especially for the PWR, which is more cost effective than other generation alternatives. Therefore, the government policy of the life extension of NPPs need to be a selective approach that simultaneously considers both safety and economics rather than closing all NPPs.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.15-26
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• 2017

This study was conducted to investigate and analyze the discharge characteristics of recyclable material from S-city, S-district, in order to improve the sorting efficiency in recycling sorting facility. The characteristics of recyclable materials collected were analyzed in three different scopes; source origin, collection and transportation, and sorting steps. The average of recyclable waste generation is $0.121kg/day^*man$. Regional collection period appears to be three times a week, and the density of mixed recyclable wastes showed the average of $202.4kg/m^3$ in the waste collection vehicle. In the analysis into the sorting steps, the average of carrying amount of mixed recycling products is 1,154.6 ton/month, the average of appeared density is $181kg/m^3$, the average amount of separated recycling products is 448.5kg/month, and the density of recycling residue is found out to be $48kg/m^3$. The sorting rate of recyclable material is 38.85% and the percentage of residues is 55.90%. Out of 7,744.8 tons of the total recyclable residues, 4,272.1 tons were found out to be possible recylable materials. As a result of increasing the recycling rate of residues, the encouragement of base-recycling, the automation and retrofit of sorting equipment, and energy recovery from recycling residue were discussed.

• Korean Journal of Remote Sensing
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• v.32 no.6
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• pp.579-587
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• 2016

To obtain a stable energy supply and manage PhotoVoltaic (PV) systems efficiently, satellite imagery methods are being developed to estimate the solar PV potential. This study analyzed trends in the use of satellite imagery in solar PV and solar irradiation estimation technology. The imaging technology is used to produce solar energy resource maps. The trend analysis showed that the level of solar PV technology in Korea is 30% below that of advanced countries. It is impossible to raise such low-level technologies to the levels of advanced countries quickly. Intensive research and development is the only way to achieve the 80% technology level of advanced countries. The information produced in this process can contribute to the management of solar power plants. A valid technology development strategy would be to obtain effective data that can be used for fieldwork. Such data can be produced by estimating solar irradiation very accurately with several-hundred-meter resolution using Communication, Ocean, and Meteorological Satellites (COMS) and next-generation GEO-KOMPSAT 2A, developing core technologies for short- and medium-term irradiation prediction, and developing technologies for estimating the solar PV potential.

• Plant Journal
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• v.10 no.2
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• pp.28-37
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• 2014

Recently, it is considered that environment and energy are critical issues all over the world. In power generation sector in Korea, almost power stations are constructed and operated as cogeneration plants in conformity with this trend. KDHC(Korea District Heating Corporation) goes one step further adopting renewable energy technology like heat pump using wasted heat for energy-saving and environment improvement. This study investigates the performance characteristics by the location of waste heat recovery heat pumps of 5 Gcal/h capacity in 150 MW-class Gwang-gyo cogeneration plant using commercial software 'THERMOFLEX'. Prior to analysis, the simulations are performed with actual operation data, and then the validation of simulations is verified by checking the error within 2%. After verification, the simulations are carried out with 3 locations and the effect on electrical power output and heat output is analyzed. As a result, overall efficiency of cogeneration plant is the highest in the case of heat pump located before DH(District Heating) Heater because of the largest increase of heat output despite of decrease of electrical power output.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.65-75
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• 2018

The wind energy produced at night is being discarded because of the excess power generated at night compared to daytime. To solve this problem, In this study, we analyzed the evaluation contents for evaluation of domestic and overseas water electrolysis systems and drew contents for safety performance contents test of the water electrolysis system based on the evaluation contents. The test contents produced the efficiency measurement test, the hydrogen generated pressure test, and the hydrogen purity test. And the safety performance evaluation of the alkaline water electrolysis system of $5Nm^3/hr$ was performed based on the results. As a result, the hydrogen generation was calculated as $5.10Nm^3/hr$ and the stack efficiency was $4.97kWh/Nm^3$. The purity of the hydrogen generated was 99.993% and it was confirmed that it produced high purity hydrogen. I think will help us assess and build safety performance of water electrolysis systems in the future.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.178-188
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• 2022

The introduction of virtual power plants is actively being discussed to solve the problem of grid acceptability caused by the spread of distributed renewable energy, which is the key to achieving carbon neutrality. However, a new business such as virtual power plants is difficult to secure economic feasibility at the initial stage of introduction because it is common that there is no compensation mechanism. Therefore, appropriate support including subsidy is required at the early stage. But, it is generally difficult to obtain the cost model to determine the subsidy level because of the lack of enough data for the new business model. In this study, a survey of domestic experts on the requirements, appropriate scale, and cost required for the introduction of virtual power plants is conducted. First, resource composition scenarios are designed from the survey results to consider the impact of the resource composition on the cost. Then, the cost estimation model is obtained using the individual cost estimation data for their resource compositions using logistic regression analysis. In the case study, appropriate initial subsidy levels are analyzed and compared for the virtual power plants on the scale of 20-500MW. The results show that mid-to-large resource composition cases show 29-51% lower cost than small-to-large resource composition cases.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.1
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• pp.13-20
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• 2007

This study was performed to provide fundamental data for long-term geomorphic predictions of estuarine sandbars in the Nakdong River. We monitored the geomorphic changes of Jinudo (Jinu Island), which is located on the far-southern side of the first western sandbar. We evaluated the temporal and spatial dynamics of the sandbar and the relationship between erosion and deposit speed with environmental factors. We found that: 1) The south side of Jinudo showed very rapid water channel closing and shoal generation. This phenomenon was more obvious during autumn (September and October) than during spring, with greater water depth reduction and variation between sides. 2) The mean deposit speed for Jinudo was approximately 0.85 mm/day. The deposit speed was 1.32 and 1.26 mm/day for the east and south sides of Jinudo, respectively. The maximum deposit and erosion speeds were 27 mm/day and 26 mm/day in July and December, respectively, on the east side of the island. 3) Mean surface deposit size was 0.18-0.26 mm. The newly deposited sandbar had a rotatively larger deposit size than the original land. 4) Correlation analysis showed that, on the southern side of the island, deposit activity prevailed in the winter due to low precipitation and a northerly wind, while erosion was dominant in the summer due to high water flow and a southerly wind. In contrast, the correlation analysis for the eastern side of the island showed that deposition is dominant when water flow is high. These results indicate that geomorphic dynamics vary among island sides.

• Clean Technology
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• v.28 no.1
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• pp.9-17
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• 2022

Electrochemical carbon dioxide (CO₂) reduction technology, one of the promising solutions for climate change, can convert CO₂, a representative greenhouse gas (GHG), into valuable base chemicals using electric energy. In particular, carbon monoxide (CO), among various candidate products, is attracting much attention from both academia and industry because of its high Faraday efficiency, promising economic feasibility, and relatively large market size. Although numerous previous studies have recently analyzed the GHG reduction potential of this technology, the assumptions made and inventory data used are neither consistent nor transparent. In this study, a comparative life cycle assessment was carried out to analyze the potential for reducing GHG emissions in the electrochemical CO production process in a more transparent way. By defining three different system boundaries, the global warming impact was compared with that of a fossil fuel-based CO production process. The results confirmed that the emission factor of electric energy supplied to CO₂-electrolyzers should be much lower than that of the current national power generation sector in order to mitigate GHG emissions by replacing conventional CO production with electrochemical CO production. Also, it is important to disclose transparently inventory data of the conventional CO production process for a more reliable analysis of GHG reduction potential.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.634-640
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• 1998

A well- shaped trench was investigated in view of the defect distribution along trench sidewall and bottom using high resolution transmission electron microscopy. The trench was formed by HBr plasma and additive gases in magnetically enhanced reactive ion etching system. Adding $0_2$ and other additive gases into HBr plasma makes it possible to eliminate sidewall undercut and lower surface roughness by forming the passivation layer of lateral etching, resulted in the well filled trench with oxide and polysilicon by subsequent deposition. The passivation layer of lateral etching was mainly composed of $SiO_xF_y$ $SiO_xBr_y$ confirmed by chemical analysis. It also affects the generation and distribution of lattice defects. Most of etch induced defects were found in the edge region of the trench bottom within the depth of 10$\AA$. They are generally decreased with the thickness of residue layer and almost disappeared below the uni¬formly thick residue layer. While the formation of crystalline defects in silicon substrate mainly depends on the incident angle and energy of etch species, the region of surface defects on the thickness of residue layer formed during trench etching.