• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.13-20
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• 2005

Fiber-Bragg-grating external cavity laser(FGL) modules were fabricated and experimentally analyzed. Proposed as a cost-effective solution for optical sources in the WDM-PON access network, FGL modules were packaged to TO-CAN type. We obtained a low threshold current of 13 mA, and an optical output power of 3.6 mW with a bias current of 60 mA at $25^{\circ}C$. The lasing wavelength dependencies on current and temperature were as small as 5.2 pm/mA and 30 pm/$^{\circ}C$, respectively. These change rates of the wavelength with the temperature and current are smaller than those of the DFB laser. Single-mode oscillations with the side-mode suppression ratio(SMSR) over 30 dB are maintained above the threshold current level. The FGL modules can be directly modulated at 155 Mbps, PRBS(2$^{23}$ -1) NRZ signal. Through the BER plots, we did not see the significant degradations before and after the transmission over 20km of the SMF at 155 Mb/s.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.501-509
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• 2015

Lately multipurpose dam is required to consider various interests such as quality, ecological environment as well as flood control, water supply, hydropower generation, etc. The objective of this study is to investigation and analysis of water temperature in the areas where there are social conflicts due to cold water outflow. In this study, we monitored water temperature of Juam regulation dam, downstream river, Suncheon bay in a long term period and performed comparative analysis on a change of water temperature in downstream river and Suncheon bay by using three-dimensional numerical mode (EFDC) considering various external factors such as water outflow amount. The result of monitoring and numerical modelling indicates that effects of cold water outflow takes place from april to september. Also effects of the low temperature discharge of dam was complicatedly altered by various factors such as outflow time and amount, weather and tide level conditions etc. The result of this study can be utilized as a basic data for establishing improvement of dam operation plan to minimize negative effects of dam's cold temperature water outflow to downstream river and coastal area.

• Journal of Korea Water Resources Association
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• v.53 no.11
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• pp.1015-1024
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• 2020

Recently, water pollution accidents have continued to occur in pipelines such as red water Incheon and Seoul. In order to recognize this water quality problem, it is necessary to install a water quality sensor in an appropriate location and measure it in advance to detect or block the water supply to the water faucet of the shelter. However, there are limitations, such as maintenance costs, to installing multiple water meters in all pipelines. Therefore, this study proposed a methodology for determining and prioritizing the installation location of flow-based water quality sensor for the recognition of water quality problems in pipelines. We applied the proposed procedure to the pipe break scenario. The results of the determination of the location of the water quality sensor were presented by applying it to the pipe network that actually operates the emergency pipe in Korea. The result of the decision showed that in the event of abnormal situation caused by the destruction of individual pipes, the flow rate of the pipes around the aqueduct and the tank may change rapidly, resulting in water quality accidents caused by turbidity. In the future, it is expected that the water quality monitoring point selection method, such as establishing an external pipe operation plan for pipe cleaning, will utilize the procedure for determining the location of the water quality sensor according to the velocity.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.529-535
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• 2015

Biological networks have been handled with the static concept. However, life phenomena in cells occur depending on the cellular state and the external environment, and only a few proteins and their interactions are selectively activated. Therefore, we should adopt the dynamic network concept that the structure of a biological network varies along the flow of time. This concept is effective to analyze the progressive transition of the disease. In this paper, we applied the proposed method to Alzheimer's disease to analyze the structural and functional characteristics of the disease network. Using gene expression data and protein-protein interaction data, we constructed the sub-networks in accordance with the progress of disease (normal, early, middle and late). Based on this, we analyzed structural properties of the network. Furthermore, we found module structures in the network to analyze the functional properties of the sub-networks using the gene ontology analysis (GO). As a result, it was shown that the functional characteristics of the dynamics network is well compatible with the stage of the disease which shows that it can be used to describe important biological events of the disease. Via the proposed approach, it is possible to observe the molecular network change involved in the disease progression which is not generally investigated, and to understand the pathogenesis and progression mechanism of the disease at a molecular level.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.57-62
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• 2006

Busan New Port, under construction aiming for the hub of Northeast Asia and Partly in operation, had damaged up to 48 billion Won due to Typhoon 'maemi' in 2003. The present criteria of domestic harbor design only describes about the critical wave height with respect to the size of vessel for harbor tranquility. The berth operation ratio which represents the annual available berthing days is depending on the efficiency of cargo handling work and this depends on the motion of the moored vessel due to the wave action and the characteristics of cargo gears. The motion of moored vessel might be related not only to the wave height but also to wave period. Furthermore, the berth operation ratio relies on external forces such as currents and winds, including the characteristics of mooring system and the specification of the moored vessel. In this study we only deal with berth operation ratio in normal sea state, considering wave and current by measured data and numerical calculation. Especially we tried to evaluate the berth operation ratio for each berth adopting the variation of dredging and reclamation plan and the change of wave environment during the process of the new port construction. For better understanding and analysis of wave transformation process, we applied the steady state spectral wave model and extended mild-slope wave model to the related site. This study summarizes comparisons of harbor responses predicted by two numerical predictions obtained at Busan New port site. Field and numerical model analysis was conducted for the original port plan and the final corrected plan.

• Environmental and Resource Economics Review
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• v.27 no.1
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• pp.67-104
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• 2018

In this paper, we compare the spread effects of the carbon tax imposition method using the real business cycle model considering the productivity and energy price shocks. Scenario 1 sets the carbon tax rate that encourages the representative firm to maintain a constant $CO_2$ reduction ratio in accordance with its green house gas reduction targets for each period. Scenario 2 sets the method of imposing the steady state value of the carbon tax rate of Scenario 1 during the analysis period. The impulse response analysis shows that the responses of $CO_2$ emissions to external shocks are relatively sensitive in scenario 2. And simulation results show that the cost of $CO_2$ abatement is more volatile in scenario 1, and $CO_2$ emissions and $CO_2$ stock are more volatile in scenario 2. In particular, the percentage changes in volatility between the two scenarios of $CO_2$ emissions and $CO_2$ stock increase as the green house gas reduction target is harder. When the green house gas reduction target is 60% and over, the percentage changes(absolute value) between the two scenarios exceed the percentage change(absolute value) of the $CO_2$ reduction cost between them.

• Journal of the Korean association of regional geographers
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• v.12 no.3
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• pp.421-435
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• 2006

This study considered the history and range of concern to the citizenship education in the British geography education with respect to the appearance of the citizenship subject in National Curriculum. Although British geography education mainly put on emphasis citizenship education focused on national identity through imperialism ideology up to World War II, it has aimed at the local and global citizenship education which put focus on the reflection of students to individual value and value position, and social justice after the 1980s. Not only an inner change of such geography education but the external factor of appearance of citizenship subject has stimulated more concern about citizenship education. After that, British geography education community constructs the logic of theoretical justification and urges teachers' practical research and continuous concern as plan for geography subject to lead citizenship education all the time. On the other hand, recently British political and social cultural geographers observe spaces of the citizenship which makes difference and identity and the radical and critical citizenship which put focus on the local and the global scale from the national. Therefore, citizenship education through geography subject must put more emphasis on not national identity but the local and global identity for social justice and a better world.

• Journal of the Korean Wood Science and Technology
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• v.40 no.1
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• pp.19-25
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• 2012

The fire retardant bamboo charcoal (BC) boards were manufactured for interior building materials in this study, The BC boards were manufactured by mixing and pressing of the bamboo charcoal, expanded vermiculite, and inorganic binder. The combustion behaviors of the BC boards were investigated using a cone calorimeter at an incident heat flux of 50 kW/$m^2$. Three building materials (plywood, BC board of Japan, and gypsum board) were used to observe the burning behaviors of weight loss, total heat release rate, and maximum heat release rate. Surface test and toxicity evaluation of the BC board were also conducted. The weight loss of the BC board (12.0%) was lower than the nonflammable gypsum board (15.6%) after burning of 10 min. Total heat release of the BC was 3 MJ/$m^2$ (KS standard 8 MJ/$m^2$) and total heat release rate of the BC was 20 kW/$m^2$ (KS standard 200 kW/$m^2$). Therefore, the BC boards were adjustable for the third-grade flame retardant building materials. External appearance change and mouse toxicity were not found in the BC boards after the combustion test.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.1
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• pp.12-27
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• 2007

This fundamental studies on for the productivity improvement and laborsaving of purse seine fishery. Given the difficulty posed from the distortion of net shape caused by the external forces, such as tide, at the time of shooting and pursing, we set the 4 steps of 0, 2, 4 and 6cm/sec in flow velocity in the flume tank for the experiment in order to examine those characteristics. We used two model seines designed on the scale of 1 to 180 based on the power block seine, which is the mackerel purse seine generally used in the near sea of Jeju Island and triplex seine, which is the mackerel purse seine of one boat system fishing expected in the future, for the experiment, and interpreted the characteristics of several motion in water, such as the shape of seine, the change in tension and area during pursing and its the analysis results are as follows. Though the experiment could be conducted up to 6cm/sec of flow velocity that was defined, the experiment could not go on because of the severe distortion in the seine at the flow velocity in excess of 6cm/sec. As for the depth of leadline and reduction rate of side area of seine when the pursing is connected, P seine turned out to be slightly higher than T seine, and the hauling speed and reduction rate of upper area of seine were found similar to each other. The correlation between the hauling time (Ht) and depth of lead line (Dhp, Dht) of P seine and T seine can be expressed by the equation, that is, Dhp=(0.99Pt-7.63)Pt+69.01, Dht=(1.03Pt-7.73)Pt+66.74. The correlation between the hauling time and hauling velocity (Hpp, Hpt) can be expressed by the equation, that is, $Hpp=-0.06Ht^2+0.88Ht+0.78,\;Hpt=-0.05Ht^2+0.81Ht+0.98$ here, Pt is pursing time. And the correlation between the pursing time and the reduction rate of side area (sArp, sArt) can be expressed by the equation, that is, $sArp=-0.48Pt^2+14.79Pt-16.74,\;sArt=-0.45Pt^2+14.56Pt-16.48$. The reduction rate of upper area of seine (tArp, tArt) can be expressed by the equation, that is, $tArp=0.34Pt^2-0.66Pt-0.74,\;tArt=0.34Pt^2-0.27Pt-1.80$. In addition, the correlation between the pursing time and tension of purse line (Tep, Tet) can be expressed by the equation, that is, $Tep=2.79Pt^2+2.26Pt-0.60,\;Tet=2.14Pt^2+8.08Pt-27.50$.

• Journal of fish pathology
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• v.22 no.2
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• pp.155-162
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• 2009

The mass mortality of Korean rockfish, Sebastes schlegeli that occured at the fish farms in Tongyeong and Geoje City regions between late August and early September in 2006 was investigated. Sixty two fish showed no significant external symptoms except ulcerative lesions with reddish foci on the skin. From the internal observations and diagnosis results, some yellowish brown liver, intestine bleeding, atrophy and congestion in the abdominal cavity of the fish were found. In the gill, swelled filaments caused by foreign material accumulation and mucus secretion were observed. However, the main cause of the fish mass mortality in both sampling regions could be due to physiological weakness induced by significant change of water temperature causing by typhoon Wookong during the summer in 2006.