• The Transactions of the Korea Information Processing Society
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• v.5 no.3
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• pp.751-762
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• 1998

The purpose of this study is to enhance the quality of multimedia service under the heterogeneous end-terminals and network environment by monitoring the data receiving status of the group members regularly when the sender multicasts real-time multimedia data to a group. Especially, it focuses to reduce the total number of status information responded to the sender from the receivers. Accordingly. it upgrades the sender's performance by suppressing the number of status information packets generated by the receivers. The key idea of this study starts from how we profile the activity of all the members in a group. We assume that the receiver status in the worst status, so called primary receiver, represents the status of the whole group. This means that the whole group is assumed as being degraded in performance if the primary receiver is degraded, and that the whole group is assumed as being upgraded if the primary one is upgraded. In this algorithm, the primary receiver announces its status information to the whole group prior to other receivers, ana every receiver listening to the primary and other receivers' status compares its own status with them. Accordingly, any receiver may give up the status notification in case its status is not worse than others, resulting in the reduction of unnecessary responses to the sender.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.268-274
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• 2011

BACKGROUND: A large scale of sediment load delivered from watershed causes substantial waterway damages and water quality degradation. Controlling sediment loading requires the knowledge of the soil erosion and sedimentation. The various factors such as watershed size, slope, climate, land use may affect sediment delivery processes. Traditionally sediment delivery ratio prediction equations have been developed by relating watershed characteristics to measured sediment yield divided by predicted gross erosion. However, sediment prediction equations have been developed for only a few regions because of limited sediment data. Besides, little research has been done on the prediction of sediment delivery ratio for asia monsoon period in mountainous watershed. METHODS AND RESULTS: In this study Tank model was expanded and applied for estimating sediment yield to Oship River of east coast. The rainfall-runoff in 2006 was verified using the Tank model and we derived good result between observed and calculated discharge in 2009 at the same conditions. In relation to sediment yield, the sediment delivery rate of 2006 was very high than 2009 regardless of methods for estimating sediment load. It was thought to be affected by heavy rainfall due to the typhoon. CONCLUSION(s): For estimating sediment volume from watershed, long-term monitoring data on discharge and sediment is needed. This model will be able to apply to predict discharge and sediment yield simultaneously in ungauged area. This approach is more effective and less expensive method than the traditional method which needs a lot of data collection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2719-2726
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• 2010

The purpose of this study was to investigate the scientific basic grounds for the assessment of health and environmental diseases resulting from air pollutants in Pohang. For this study, we investigated pollutants, weather characteristics and concentration distribution of fine particles ($PM_10$) yearly and each season, using data from Air Quality Monitoring Stations. The properties of concentration distribution and seasonal fluctuation of $PM_10$ were studied qualitatively and quantitatively using CALPUFF, air dispersion model. The average concentration of $PM_10$ for each season was spring($75.7{\mu}g/m^3$)>summer($56.8{\mu}g/m^3$)>winter($53.6{\mu}g/m^3$)>fall( $52.7{\mu}g/m^3$). In the case of spring, high concentrations appear due to the Asian dust frequently occurring. The contributions of $PM_10$ classified by the types of pollution source in Pohang were point source 62%>mobile source 33%>area source 5%. An important point is that 97% of emissions were produced from the iron manufacture in steel industry. Therefore, it is necessary to control the emission sources of pollutants and to construct an observation system at Pohang steel industrial complex from now on. It’s time to control the risk factors for health and environmental disease to protect the health of resident in Pohang and its neighboring areas.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.319-330
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• 2001

In virtual memory system, when a process attempts to access a page that is not resident in memory, the system generates and handles a page fault that causes unpredictable delay. So virtual memory system is not appropriate for the real-time system, because it can increase the deadline miss ratio of real-time task. In multimedia system, virtual memory system may degrade the QoS(quality of service) of multimedia application. Furthermore, in general-purpose operating system, whenever a new task is dynamically loaded, virtual memory system suffers from extensive page fault that cause transient overloading state. In this paper, we present efficient overloading control mechanism called RBPFH (Rate-Based Page Fault Handling). A significant feature of the RBPFH algorithm is page fault dispersion that keeps page fault ratio from exceeding available bound by monitoring current system resources. Furthermore, whenever the amount of available system resource is changed, the RBPFH algorithm dynamically adjusts the page fault handling rate. The RBPFH algorithm is implemented in the Linux operating system and its performance measured. The results demonstrate RBPFH\`s superior performance in supporting multimedia applications. Experiment result shows that RBPFH could achieve 10%∼20% reduction in deadline miss ratio and 50%∼60% reduction in average delay.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.1-7
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• 2005

High-quality single crystals of pure $Li_2B_4O_7$ as well as $Li_2B_4O_7$ doped with Cu, Mn and Mg impurities (1.0mol%, respectively) have been grown from the melt of $Li_2CO_3+2B_2O_3$ by Czochralski method in platinum crucibles. To study the thermoluminescent properties, $Li_2B_4O_7$ series single crystal TLDs were made by cutting in the size of $4{\times}5{\times}1\;mm^3$. The glow curves show two or three peaks which can be easily deconvoluted. It is observed that room temperature($20{\sim}30^{\circ}C$) fadings of the dosimetric peaks of $Li_2B_4O_7$ series single crystal TLDs were about 10 % for 30 days. The relative photon energy response for $Li_2B_4O_7$ series single crystal TLDs were about 85 % when the responses were normalized to that measured with $^{60}Co\;(1.25\;MeV)\;{\gamma}-rays$. The measured data are in a good agreement with theoretical ones. The $Li_2B_4O_7$ series single crystal TLDs fabricated in this work can be used for monitoring personal and environmental radioactivity.

• Journal of Wetlands Research
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• v.20 no.1
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• pp.72-79
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• 2018

Two planter boxes were monitored during their initial year of operation to be able to assess their stormwater runoff and pollutant reduction capabilities and investigate on the design factors affecting their performance. One of the planter boxes provided 85-100% runoff volume reduction for rainfall less than 15 mm and rainfall intensities lower than 5 mm/hr. This reduced to 50-64% during higher rainfall intensities and depths of up to 50 mm. Suspended solids, organics, nutrients, and heavy metals were satisfactorily removed at a range of 40-95%. The other planter box, however, did not produce outflow in all the events and allowed total capture of stormwater. The uncertainty regarding the fate of the runoff in that case required an investigation of the planter box's actual drainage and underground conditions which was deemed outside the scope of the study. Nonetheless, several design improvements and retrofits were suggested based on the provisions of current design guidelines to ensure that the hydraulic and water quality goals are achieved without potential damage to nearby structures. Moreover, continuous monitoring data is required to provide more accurate design evaluation and can serve as a guide in the construction of similar facilities in the future.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.2
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• pp.110-115
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• 2011

Objectives: The aim of this study is to survey for finding asbestos containing equipment at the laboratories using picture based questionnaire and polarized light microscopic analysis. Methods: This study was conducted from 2009 to 2010 at a university in Seoul. In 2009, picture based questionnaire was distributed to 100 laboratories during the regular laboratory air quality monitoring. In 2010, we emailed all professors of the same university who have laboratories to participate voluntarily this survey. For the laboratories consented to participate survey, picture based questionnaire was distributed and collected. Suspected asbestos containing material and apparatus were collected at the laboratories which replied they have suspected material and equipment. Collected samples were analyzed with polarized light microscope at the laboratory accredited by ministry of employment and labor in Korea. Results: Total of 18 out of 100 laboratories reported that they had suspected asbestos containing equipment in 2009. Twenty-three samples were collected and three samples (13%), one heating mantle and two pairs of insulation gloves, contained asbestos. Thirty four laboratories reported they had suspected asbestos containing material or equipment in 2010. Sixty samples were collected and four of them (6%), two pairs of insulation gloves, one packing rope in dry oven and, one pair of tongs, contained asbestos. All founded asbestos was chrysotile and the content of chrysotile was more than 90% for all equipment except heating mantle which has less than 1%. Conclusions: We confirmed that asbestos was still used at the laboratories though strict regulations on asbestos use in Korea. The method of picture based questionnaire invented in this study could be applied for asbestos survey to other research institute or university where there are many laboratories because of its simplicity and accessibility without huge man power, cost and time.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.139-144
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• 2005

To investigate the long-term variation of water qualities, we have daily monitored physio-chemical characteristics of surface water in the Geum River estuary from June 1996 to April 2004. We found that the water qualities were determined by three dominant factors : 1. fluvial input from Geum River ($28.3\%$), 2. chemical processes such as nitrification and phosphate addition originated from sediment resuspension and domestic sew- age input ($18.6\%$), 3. biological processes such as nutrient consumption by primary producers ($13.5\%$). The factor 1 (fluvial input) effectively affected the water quality of the estuary particularly during the normal or low river discharge. The factor 2 (chemical processes) and the factor 3 (biological processes) showed distinct seasonal differences due to their relative strengths of biological activities. The factor 3 was a governing parameter during the period of spring algal bloom in 2004. For the spring period, an empirical equation derived from the multi-regression analyses showed that the in-situ chlorophyll-a distributions in the estuarine water were successfully simulated by the phosphate concentrations and N/P ratios. Therefore we suggest that phosphate functions as a limiting factor for the primary productivity in the Geum River estuary for the dry season, especially during spring.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.3
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• pp.57-68
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• 2017

Continuous monitoring of spatial and temporal changes in key marine environmental parameters such as SST (sea surface temperature) near IORS (Ieodo Ocean Research Station) is demanded to investigate the ocean ecosystem, climate change, and sea-air interaction processes. In this study, we aimed to develop the system for continuously measuring SST using a TIR (thermal infrared) sensor mounted at the IORS. New SST algorithm is developed to provide SST of better quality that includes automatic atmospheric correction and emissivity calculation for different oceanic conditions. Then, the TIR-based SST products were validated against in-situ water temperature measurements during May 17-26, 2015 and July 15-18, 2015 at the IORS, yielding the accuracy of 0.72-0.85 R-square, and $0.37-0.90^{\circ}C$ RMSE. This TIR-based SST observing system can be installed easily at similar Ocean Research Stations such as Sinan Gageocho and Ongjin Socheongcho, which provide a vision to be utilized as calibration site for SST remotely sensed from satellites to be launched in future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.120-125
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• 2016

For the purpose of protecting personal property and lives from incidents, accidents, and threats such as terrorism, video surveillance equipment has been installed and operates in many places. Video surveillance technology has gradually developed into high-quality, high-definition equipment, and a lot of products have been launched. However, closed circuit television (CCTV) equipment for security purposes can invade a person's privacy. In this paper, we propose a way to protect personal video images using meta-data in an intelligent Internet protocol (IP) camera. We designed the system to mask personal video information from meta-data, define the method of image-information access according to user privileges, and show how to utilize the meta-data during storage and recorded data searches. The suggested system complies with guidelines for CCTV installation and operation from Korea's Ministry of the Interior. Installed on only a single server so far, due to the limitations and technical difficulties of hardware performance, it has been difficult to find a method that can be applied to personal image information using real-time protection techniques. Applying the method proposed in this paper can satisfy the guidelines, reduce server costs, and reduce system complexity.