• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.111-118
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• 2009

A hybrid SNCR/SCR plant was designed and manufactured, and experimented on the SNCR process in the first step to investigate the optimum operation conditions of SNCR, with the equivalence ratio of the reducing agent(NSR, 0.5~5.0), reaction temperature($850{\sim}1,100^{\circ}C$), nozzle type(wall nozzle, pipe nozzle), and nozzle position as variables. In the case of wall nozzles, the NOx reduction efficiency rapidly increased to 87% at 2.5 NSR and slowed down after this. Compared to the upward spray from the pipe nozzle, wall nozzles have narrower range of applicable reaction temperature. In the case of pipe nozzles, it rapidly increased to 77% at 1.5 NSR. But the pipe nozzle downward had no NOx reduction efficiency; on the contrary, NOx increased. When the reducing agent was sprayed upward from a pipe nozzle, the NOx reduction efficiency was 50~75% in the range of 0.5~1.5 NSR, and the NOx reduction efficiency was constant without fluctuations even in the change of reaction temperature from 890 to $1,000^{\circ}C$. When 5% urea solution was sprayed upward from the pipe nozzle, 200 ppm NOx decreased to approximately 60 ppm at 1.2 NSR, and the non-reacted $NH_3$ was 50~100 ppm. In this condition, we expect over 90% NOx reduction efficiency without additional supply of $NH_3$ to SCR at the back of SNCR.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.195-206
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• 1993

The purpose of this study is to provide a basis for establishing regional harvesting systems that ist the prerequisites for the forest mechanization. The factors restricting to the forest harvesting and logging methods from topographical aspects are studied for this purpose. Three main harvesting methods studied in this paper are : shortwood method, longwood method and full tree method. This study shows : the shortwood method is suitable for low, the longwood method for medium, the full tree method for high topographical conditions. For the logging methods, the focus of the study is on various ground based logging systems by animalpower, manpower, gravitation, wheeled & crawler vehicle and cable. The factors limiting the coverage of logging operation are slope and logging distance. The cable crane logging methods are classified by logging distance into short distance(to 300 or 400m), middle distance(to 700 or 800m) and long distance cable crane methods (over 700 or 800m). The wheeled vehicle method shows serious damages to forest resources, whereas the logging by log-line of the gravitation logging method and cable crane method tend to minimize such damages. The wheeled & crawler vehicle method also shows difficult to apply in the high slope conditions, whereas cable crane method can be applied to maximum 120% steep slope and uphill conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.536-543
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• 2016

The installation of grounding systems is important for the safe operation of power systems, and the soil resistivity is an important design consideration for such systems. It varies markedly with the soil type, moisture content and temperature. The Jeju geological structure is formed in a multi-layered structure characteristic of volcanic areas and, and the geological ground resistance values can appear even constructed the same areas ground system different from the soil structure. In this study, a mock-up system using representative soil from Jeju was constructed to analyze the variation of the grounding resistance. The mock-up system was configured using the Gauss-Newton algorithm inversion method to analyze the model numerically using the Wenner method through the soil resistivity measurements used to create the ground model. Also, we analyzed the change in the general ground resistance characteristics of the copper rod, copper pipe, and carbon rod that are used for grounding. The variation of the grounding resistance with the hydration status was found to be $2.9[{\Omega}]$, $16.5[{\Omega}]$ and $20.1[{\Omega}]$ for the copper rod, copper pipes, and carbon rod, respectively, and the influence of the ground moisture resistance of the carbon rod was found to be the lowest with a value of $141[{\Omega}]$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.535-545
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• 2019

The PBA of ship weapon system should be installed and operated under harsh environmental conditions and so it should be highly reliable to endure the mission profiles during its entire lifetime. In the case of PBA failure during operation, rapid maintenance is highly likely to be difficult due to problems such as supply of parts, which can have a devastating effect on the mission. In order to validate the reliability of PBA, a series of tests are performed with PBA samples, but they require time, testing facilities, samples, expenses and failure analysis if failed. The reliability of PBA is predicted on the basis of specifications such as MIL-HDBK-217F, but this specification does not take into account failure mechanisms for specific design details, environment and usage, interconnects and its characteristics that drive many failures of PBA in the field. Therefore, this study predicts the reliability of PBA using an RPA tool and proposes the RPA methodology as a validation process at the design stage. With RPA, it is now possible to achieve design validation including inherent failure mechanism, identification of weakest link, alternative design options, and test plan development.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.76-82
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• 2019

The development of Internet technology and the deployment of smart devices provide a convenient environment for people, and this is becoming common with the technology called the Internet of Things (IoT). But the development of, and demand for, IoT technology is causing various problems, such as personal information leaks due to the attacks of hackers who exploit it. A number of devices are connected to a network, and network attacks that have been exploited in the existing PC environment are occurring in the IoT environment. When it comes to IP cameras, security incidents (such as distributed denial of service [DDoS] attacks, hacking someone's personal information, and monitoring without consent) are occurring. However, it is difficult to install and implement existing security solutions because memory space and power are limited owing to the characteristics of small devices in the IoT environment. Therefore, this paper proposes a security protocol that can look at and prevent IoT security threats. A security assessment verified that the proposed protocol is able to respond to various security threats that could arise in a network. Therefore, it is expected that efficient operation of this protocol will be possible if it is applied to the IoT environment.

• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.203-214
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• 2005

The integration of 3G networks and WLANs as complementary has been begun to attract much attention in industry as well as academia. This topic is becoming a burning issue, and one of the key questions which it raises is how to support a seamless vertical handoff. This paper introduces a new network interface selection algorithm for energy-efficient vertical handoff in tightly coupled systems capable of supporting seamless handoff. Our proposed scheme, Wise Interface Selection (WISE) switches the active network interface, after taking into consideration the characteristics of the network interface cards and the current level of data traffic, with the cooperation of the mobile terminals and network. Network interface switching operates independently on both the downlink and the uplink for the purpose of energy conservation. We show through simulation that less energy is consumed with WISE than when only a 3G network or WLAN interface is used, resulting in a longer lifetime for the mobile terminals. In the case of TCP connections, additional throughput gain can also be obtained.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.89-96
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• 2005

As the number of the municipalities which have finished the phase I of their GIS system development projects increases, it is very natural that GIS system operation and maintenance rather than development itself has been a more important concern for these municipalities. It seems to me that these phenomena will be amplified as time goes by, and this is the right time for a series of proper guidelines regarding the GIS system maintenance to be supplied to the related municipalities. The subject which is called as 'GIS maintenance' is surely a very comprehensive area. It has been also founded that the necessity is widely agreed among the concerned people working for the municipalities which have already finished their first GIS projects. Nevertheless, it has been investigated that the studies done up to now in this area is in a very infant state from the quality and also quantity points of views. This paper, therefore, makes one of the very initial trials for the systematical GIS maintenance. Among the areas of GIS maintenance, the GIS database maintenance has been selected as the first trial area because of its natural characteristics of the basic element composing IS(Information System). For this, the present conditions of a variety of municipalities have been investigated as far as GIS maintenance is concerned, and the results are analyzed to produce a series of useful outcomes in terms of facing problems and accompanied plans. For each problem, a solution is defined and for each solution a detailed action plan (item) is derived. For each of the two kinds of GIS data given which are the fundamental map and the underground facilities map, an effective GIS data maintenance plan is suggested for the concerned municipalities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.1023-1031
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• 2014

This study is conducted to evaluate the supply effectiveness of the Long-term Secured Public Rental Housing (LSPRH) program implemented by the City of Seoul since March, 2012. To estimate the residential intention of potential applicants for the housing program, two logistic regression models of residential intention are estimated based on the residential characteristics of real residents. The purpose of this model estimation is to find out factors influencing the supply of LSPRH and thus to suggest the ideas for improving the effectiveness of the rental housing program operation. The analysis result shows that financial condition, income level, and public support are the major determinants for selecting LSPRH. It is also revealed that those who are currently living in rental housing or living in a house more expensive than those in nearby areas have higher residential intention for the LSPRH program. The result also presents that some problems associated with the traditional rental housing programs - such as visually recognizable low-quality exterior building design or the concentration of rental housing on limited spots - could be solved by this new type of public housing program. Lastly, one interesting finding different from previous research is that people with the intention to move into either traditional rental housing or LSPRH do not necessarily prefer a more spacious house than their current rental house.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.1
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• pp.105-111
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• 1999

To investigate the relationships between ocean environmental characteristics and thechange of the catch, we analyzed various environmental factors such as mean temperature, salinity, current vectors, lunar day and wind vectors from 1995 to 1996 and the catch fluctuation of Hanlim set net from 1994 to 1996. The results are as follow ; 1) The proportion of fishes caught in Hanlim set net is highest for horse mackere1 ($69.2\%$) and is followed by common mackerel ($18.4\%$), hair tail ($5.6\%$), squid ($2.7\%$) and rabbit fish ($1.4\%$) in order. Two peaks in the monthly catch appeared in June and October in the operation period of May- December. 2) The flow direction was northward in flood time and southeastward in ebb time around the Hanlim set net. Thus, the vortical mixing of sea water was active and continued for more than 3 hours. In addition, mean daily temperature was low due to the presence of middle and bottom water in offshore. Increase in salinity or high salinity of sea water provides a favorable condition for catches of fishes. Catches in the first quarter and the last quarter of the moon were larger than that in full moon and the last of the month. In particular, when south or southeasterly wind velocity reaches about 3$\~$6.5 m/s, the possibility of catches increases.

• Journal of Digital Convergence
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• v.15 no.5
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• pp.207-215
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• 2017

With rapid development of IT technology and biotechnology, human lifespan is extended rapidly, and we are living in the era where aging becomes the social issue. Due to this aging problem, manpower is mainly replaced by Automated Guided Vehicles (AGV) in manufacturing factories or warehouse logistics transportation. Rate of AGV use increases sharply every year. AGVs, which were used only in Smart Factories, extends its usage into indoor and outdoor operation by changing their usages to container transportation that can carry huge containers in the harbor. With the expansion of AGVs usage, the importance of RCS (Remote Control System) is also increased. In this study, we surveyed and analyzed the characteristics and technology trends of technical features of AGV's RCS that are developing in various ways to establish quality evaluation system of AGV RCS. Based on this, and by referring to international quality assessment standards, ISO/IEC 25000 series, we derived evaluation items on functional suitability and usability to secure reliability of AGV RCS. Also, it is our intention to develop evaluation model using those derived usability and reliability evaluation items.