• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.11
• /
• pp.581-586
• /
• 2015

In this study, an analysis was performed on the performance of the solar water heating system with geo-thermal heat pump for a detached house. This system has a flat plate solar collector ($8\;m^2$) and a 3 RT heat pump. The heat pump acts as an auxiliary heater of the solar water heating system. These systems were installed at four individual houses with the same area of $100\;m^2$. The monitoring results for one year are as follows. (1) The average daily operating time of the solar system appeared to be 313 minutes in spring (intermediate season), and 135 minutes and 76 minutes in winter and summer respectively. The reason for the short operating time in summer is the high storage temperature due to low water heating load. The high storage temperature is caused by a decrease in collecting efficiency as well as by overheating. (2) The geothermal heat pump as an auxiliary heater mainly operates on days of poor insolation during the winter season. (3) Despite controlling for total house area, hot water consumption varies greatly according to the number of people in the family, hot water usage habits, etc. (4) The yearly solar fraction was 69.8 to 91.5 percent, which exceeds the maximum value of 80% as recommended by ASHRAE. So the solar collector area of $8\;m^2$ appeared to be somewhat greater for the house with an area of $100\;m^2$. (5) The observed annual efficiency of solar systems was relatively low at 13.5 to 23.6%, which was analyzed to be due to the decrease in thermal efficiency and the overheating caused by a high solar fraction.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.1-8
• /
• 2016

Current sensors are used widely in the fields of current control, monitoring, and measuring. They have become more popular with the increasing demand for smart grids in a power network, generation of renewable energy, electric cars, and hybrid cars. Although open loop Hall effect current sensors have merits, such as low cost, small size, and weight, they have low accuracy. This paper describes the design and fabrication of a 300A open loop current sensor that has high accuracy and temperature performance. The core of the current sensor was calculated numerically and the signal conditioning circuits were designed using circuit analysis software. The characteristics of the manufactured open loop current sensor of 300 A class was measured at currents up to 300 A. According to the test of the current sensor, the accuracy error and linearity error were 0.75% and 0.19%, respectively. When the temperature compensation was carried out with the relevant circuit, the temperature coefficients were less than $0.012%/^{\circ}C$ at temperatures between $-25^{\circ}C$ and $85^{\circ}C$.

• Journal of Korean Society for Atmospheric Environment
• /
• v.26 no.5
• /
• pp.475-489
• /
• 2010

In order to verify the enhancement of ozone and carbon monoxide (CO) during springtime in East Asia, we investigated weather conditions and data from remote sensors, air quality models, and air quality monitors. These include the geopotential height archived from the final (FNL) meteorological field, the potential vorticity and the wind velocity simulated by the Meteorological Mesoscale Model 5 (MM5), the back trajectory estimated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the total column amount of ozone and the aerosol index retrieved from the Total Ozone Mapping Spectrometer (TOMS), the total column density of CO retrieved from the Measurement of Pollution in the Troposphere (MOPITT), and the concentration of ozone and CO simulated by the Model for Ozone and Related Chemical Tracers (MOZART). In particular, the total column density of CO, which mightoriginate from the combustion of fossil fuels and the burning of biomass in China, increased in East Asia during spring 2000. In addition, the enhancement of total column amounts of ozone and CO appeared to be associated with both the upper cut-off low near 500 hPa and the frontogenesis of a surface cyclone during a weak Asian dust event. At the same time, high concentrations of ozone and CO on the Earth's surface were shown at the Seoul air quality monitoring site, located at the surface frontogenesis in Korea. It was clear that the ozone was invaded by the downward stretched vortex anomalies, which included the ozone-rich airflow, during movement and development of the cut-off low, and then there was the catalytic photochemical reaction of ozone precursors on the Earth's surface during the day. In addition, air pollutants such as CO and aerosol were tracked along both the cyclone vortex and the strong westerly as shown at the back trajectory in Seoul and Busan, respectively. Consequently, the maxima of ozone and CO between the two areas showed up differently because of the time lag between those gases, including their catalytic photochemical reactions together with the invasion from the upper troposphere, as well as the path of their transport from China during the weak Asian dust event.

• Korean Journal of Remote Sensing
• /
• v.30 no.6
• /
• pp.743-754
• /
• 2014

In this present paper, we, for the first time, calculated $SO_2$ inflow from China to Korea peninsula based on OMI $SO_2$ products and HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) backward trajectory calculations. The major factors used to estimate $SO_2$ flux are long range transported $SO_2$ concentration, transport speed of air mass, and thickness of transported air mass layer. The mean and maximum $SO_2$ fluxes are estimated to be 0.81 and $2.11g{\cdot}m^{-2}{\cdot}h^{-1}$, respectively based on OMI products while, those of $SO_2$ fluxes are 0.50 and $1.18g{\cdot}m^{-2}{\cdot}h^{-1}$ respectively using insitu data obtained at the surface. For most cases, larger $SO_2$ inflow values were found at the surface than those estimated for the air mass layer which extends from surface up to 1.5 km. However, increased transport speed of air mass leads to the enhanced $SO_2$ flux at the altitude up to 1.5 km at the receptor sites. Additionally, we calculate uncertainties of $SO_2$ flux using error propagation method.

• The Journal of the Korea Contents Association
• /
• v.11 no.12
• /
• pp.78-87
• /
• 2011

A variety of intelligent application using the sensor network system is being studied. In general, the sensor network consists of nodes which equipped with a variety of sensing module and is utilized to collect environment information. Recently, the demands of multimedia data are increasing due to the demands of more detailed environmental monitoring or high-quality data. In this paper, we overcome the limitations of low bandwidth in Zigbee-based sensor networks and propose a routing algorithm for real-time multimedia data transmission. In the previously proposed algorithm for multimedia data transmission occurs delay time of routing setup phase and has a low data transmission speed due to bandwidth limitations of Zigbee. In this paper, we propose the hybrid routing algorithm that consist of Zigbee and Bluetooth and solve the bandwidth problem of existing algorithm. We also propose the disjointed multipath setup algorithm based on competition that overcome delay time of routing setup phase in existing algorithm. To evaluate the superiority of the proposed algorithm, we compare it with the existing algorithm. Our experimental results show that the latency was reduced by approximately 78% and the communication speed is increased by approximately 6.9-fold.

• Journal of Environmental Impact Assessment
• /
• v.29 no.2
• /
• pp.144-155
• /
• 2020

This research developed an approach to identify ecologically important areas at local scales and explained how the results of this approach could contribute to extend the protected areas in the Republic of Korea (ROK). While most developed countries have considered various biotic and abiotic factors, ecological processes, migration routes, habitat connectivity, ecosystem services, and etc. to determine the protected areas, ROK has considered a few factors focusing on biodiversity, landscape, and the habitats of endangered organisms. However, for sustainable management of our nature, we need comprehensive understanding of various ecosystem factors and interactions among them at local scales in designating protected areas. Forthis, we developed a conceptual model based on the ecological engineering approach and then explained how the results of this approach could contribute to extend the protected areas. In particular, we considered future land-use and climate change in determining the priority areas for novel protected areas. Our research suggested an effective methodology 1) to include various ecosystem factors and 2) to consider future environmental changes as well as current environmental conditions in finding the ecologically important areas and prioritizing these areas. However, our approach has limitations on the real-world applications due to the lack of fundamental information and data on our ecosystems. To improve the effectiveness of our approach in the real-world applications, we need various long-term ecological research results, environmental and ecological monitoring data, and both current and future spatial environmental data.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.11
• /
• pp.183-190
• /
• 2012

Conventional physical activity monitoring systems, which use accelerometers, global positioning system (GPS), heartbeats, or body temperature information, showed limited performances due to their own restrictions on measurement environment and measurable activity types. To overcome these limitations, we developed a portable exercise analysis system that can analyze aerobic exercises as well as isotonic exercises. For bioelectric signal acquisition during exercise, waist belt with two body contact electrodes was used. For exercise analysis, the measured signals were firstly divided into two signal groups with different frequency ranges which can represent respiration related signal and muscular motion related signal, respectively. After then, power values, differential of power values, and median frequency values were selected for feature values. Selected features were used as inputs of support vector machine (SVM) to classify the exercise types. For verification of statistical significance, ANOVA and multiple comparison test were performed. The experimental results showed 100% accuracy for classification of aerobic exercise and isotonic resistance exercise. Also, classification of aerobic exercise, isotonic resistance exercise, and hybrid types of exercise revealed 92.7% of accuracy.

• Asian-Australasian Journal of Animal Sciences
• /
• v.19 no.12
• /
• pp.1761-1768
• /
• 2006

In this study, the comparative effects of transgenic corn (Mon 810 and Event 176) and isogenic corn (DK729) were investigated for their influence on in vitro rumen fermentation. This study consisted of three treatments with 0.25 g rice straw, 0.25 g of corn (Mon810/Event176/DK 729) mixed with 30 ml rumen fluid-basal medium in a serum bottle. They were prepared in oxygen free conditions and incubated at $39^{\circ}C$ in a shaking incubator. The influence of transgenic corn on the number of bacterial population, F. succinogenes (cellulolytic) and S. bovis (amylolytic), was quantified using RT-PCR. Fermentative parameters were measured at 0, 2, 4, 8, 12 and 24 h and substrate digestibility was measured at 12 and 24 h. No significant differences were observed in digestibility of dry matter, NDF, ADF at 12 and 24 h for both transgenic and isogenic form of corns (p>0.05) as well as in fermentative parameters. Fluid pH remained unaffected by hybrid trait and decreased with VFA accumulation as incubation time progressed. No influence of corn trait itself was seen on concentration of total VFA, acetic, propionic, butyric and valeric acids. There were no significant differences (p<0.05) in total gas production, composition of gas (methane and hydrogen) at all times of sampling, as well as in NH3-N production. Bacterial quantification using RT-PCR showed that the population number was not affected by transgenic corn. From this study it is concluded that transgenic corn (Mon810 and Event 176) had no adverse effects on rumen fermentation and digestibility compared to isogenic corn. However, regular monitoring of these transgenic feeds is needed by present day researchers to enable consumers with the option to select their preferred food source for animal or human consumption.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_3
• /
• pp.1013-1025
• /
• 2020

Unmanned Aerial Vehicle (UAV) platform is being widely used in disaster monitoring and smart city, having the advantage of being able to quickly acquire images in small areas at a low cost. Ground Control Points (GCPs) for positioning UAV images are essential to acquire cm-level accuracy when producing UAV-based orthoimages and Digital Surface Model (DSM). However, the on-site acquisition of GCPs takes considerable manpower and time. This research aims to provide an efficient and accurate way to replace the on-site GNSS surveying with three different sources of geospatial data. The three geospatial data used in this study is as follows; 1) 25 cm aerial orthoimages, and Digital Elevation Model (DEM) based on 1:1000 digital topographic map, 2) point cloud data acquired by Mobile Mapping System (MMS), and 3) hybrid point cloud data created by merging MMS data with UAV data. For each dataset a three-dimensional positional accuracy analysis of UAV-based orthoimage and DSM was performed by comparing differences in three-dimensional coordinates of independent check point obtained with those of the RTK-GNSS survey. The result shows the third case, in which MMS data and UAV data combined, to be the most accurate, showing an RMSE accuracy of 8.9 cm in horizontal and 24.5 cm in vertical, respectively. In addition, it has been shown that the distribution of geospatial GCPs has more sensitive on the vertical accuracy than on horizontal accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.8
• /
• pp.1103-1109
• /
• 2021

ECS is a control device so that the warship can perform the mission stably by controlling and monitoring the entire propulsion system. As the recent provisions of the warship, it's propelling system is complicated than past, as the demand performance and mission of the warships are diverse. In accordance with the complicated propulsion system configuration, the demand for automatic control function of the ECS is increasing for convenient and stable propulsion system control for convenient and stable. As a result, verification of ECS stability and reliability is required. In this paper, we develop an interlocking signal simulator for verifying ECS control logic and communication protocol for warship with CODLOG propulsion systems. The simulator developed was implemented to simulate a signal of gas turbine, propulsion motors, diesel generator and 11 kinds of auxiliary equipment. The reliability of ECS was verified through the ECS communication program and the I/O signal static test with the simulator.