• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.350-357
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• 2017

Purpose: In-situ monitoring of water quality is fundamental to most environmental applications. The high cost and long delays of conventional laboratory methods used to determine water quality, including on-site sampling and chemical analysis, have limited their use in efficiently managing water sources while preventing environmental pollution. The objective of this study was to develop an on-site water monitoring system consisting mainly of an Arduino board and a sensor array of multiple ion selective electrodes (ISEs) to measure the concentration of $NO_3$ ions. Methods: The developed system includes a combination of three ISEs, double-junction reference electrode, solution container, sampling system consisting of three pumps and solenoid valves, signal processing circuit, and an Arduino board for data acquisition and system control. Prior to each sample measurement, a two-point normalization method was applied for a sensitivity adjustment followed by an offset adjustment to minimize the potential drift that could occur during continuous measurement and standardize the response of multiple electrodes. To investigate its utility in on-site nitrate monitoring, the prototype was tested in a facility where drinking water was collected from a water supply source. Results: Differences in the electric potentials of the $NO_3$ ISEs between 10 and $100mg{\cdot}L^{-1}$ $NO_3$ concentration levels were nearly constant with negative sensitivities of 58 to 62 mV during the period of sample measurement, which is representative of a stable electrode response. The $NO_3$ concentrations determined by the ISEs were almost comparable to those obtained with standard instruments within 15% relative errors. Conclusions: The use of the developed on-site nitrate monitoring system based on automatic sampling and two-point normalization was feasible for detecting abrupt changes in nitrate concentration at various water supply sites, showing a maximum difference of $4.2mg{\cdot}L^{-1}$ from an actual concentration of $14mg{\cdot}L^{-1}$.

• Proceedings of the KACD Conference
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• 2008.05a
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• pp.198-203
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• 2008

The purpose of this study was to compare the sealing abilities of four endodontic temporary restorative materials using a methylene blue dye penetration test under dynamic loading. Standardized access cavities were prepared in forty-four intact human permanent molar teeth, and the cavities were restored with Caviton, MD-Temp, IRM, or ZOE. After thermocycling, an intermittent load of 98 N at 1 Hz was applied for 1,000 cycles to the long axis of the functional cusp of each of the teeth, which were immersed in a 1% methylene blue solution. The teeth were split in half, and the linear depth of dye penetration was evaluated according to the criteria. The results were analyzed using one-way ANOVA (p = 0.05) and Duncan's multiple range test. The results demonstrated that Caviton and MD-Temp showed significantly lower microleakage than IRM and ZOE. It was concluded that Caviton and MD-Temp exhibited better sealing ability than IRM and ZOE under dynamic loading.

• Journal of Korean Society of Disaster and Security
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• v.5 no.2
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• pp.49-59
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• 2012

The safety management of the emergency exit, by directly related to the $civil^{\circ}$Øs dead in the fire situation, have limited by which the fire station take the on-side and control-centered way of business processing, it is expect to the effects in which the citizen have to concern and to take part. From 2010 years in the back-ground, it is operated nationally the report and reward system on an illegal behavior of the emergency exit, it is happened to the unfit operating situation in the mission and direction of the system up which the exit paparazzi act with intent to receive the reward payments. The study suggests solution through analyzing the illegal emergency exit operation result of sixteen counties and the Seoul metropolitan from year 2010 to 2011. Firstly, the report destination is adjusted to the multiple use establishments and the large-scale multiple use facilities over the limit level is limited under five times the report events of the same people in the minor endorsement. And the fine incomes should be invested to the disaster prevention acting related with the exit. Secondly, for upgrade of the report accuracy, a reporter is received the possible information for the confirmation of an illegal act, has become to lead the pre-monitoring act which the reporter is can to take the safety education and to guide the information about season and vulnerable business location. Finally, considering the support way about the encounter facility, the fire officer is not happen to occur the repetitive report in the same place, is related to the volunteer service system the report acts, consider as the volunteer service time, and must support them to act as the disaster prevention volunteer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1397-1404
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• 2015

Recently, high data rate transmission is required in maritime communication. In this paper, we consider multiple input multiple output (MIMO) spatial multiplexing (SM). However, the performance of SM is severly degraded due to spatial channel correlation and line-of-sight (LOS) component. In the maritime communication, the MIMO channel correlation and LOS are critical due to the lack of scatteres around the transmitter and/or the receiver. When the feedback of channel information is available, precoding can enhance the error performance by exploiting the channel information. However, it is difficult to derive closed-form solution considering both the correlation and LOS. In this paper, we present open-loop precoding-based spatial multiplexing transmission method by showing that the effect of performance for the correlation and LOS. It is shown that the open-loop precoding can mitigate the performance degradation due to the LOS as well as the correlation. Consequently, we expect that the proposed open-loop precoding can be adopted to the maritime communication system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.413-420
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• 2012

In this study, the Kernel integration scheme for 2D linear elastic direct boundary element method has been discussed on the basis of subparametric element. Usually, the isoparametric based boundary element uses same polynomial order in the both basis function and mapping function. On the other hand, the order of mapping function is lower than the order of basis function to define displacement field when the subparametric concept is used. While the logarithmic numerical integration is generally used to calculate Kernel integration as well as Cauchy principal value approach, new formulation has been derived to improve the accuracy of numerical solution by algebraic modification. The subparametric based direct boundary element has been applied to 2D elliptical partial differential equation, especially for plane stress/strain problems, to demonstrate whether the proposed algebraic expression for integration of singular Kernel function is robust and accurate. The problems including cantilever beam and square plate with a cutout have been tested since those are typical examples of simple connected and multi connected region cases. It is noted that the number of DOFs has been drastically reduced to keep same degree of accuracy in comparison with the conventional isoparametric based BEM. It is expected that the subparametric based BEM associated with singular Kernel function integration scheme may be extended to not only subparametric high order boundary element but also subparametric high order dual boundary element.

• Restorative Dentistry and Endodontics
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• v.33 no.3
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• pp.198-203
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• 2008

The purpose of this study was to compare the sealing abilities of four endodontic temporary restorative materials using a methylene blue dye penetration test under dynamic loading. Standardized access cavities were prepared in forty-four intact human permanent molar teeth, and the cavities were restored with Caviton, MD-Temp, IRM, or ZOE. After thermocycling, an intermittent load of 98 N at 1 Hz was applied for 1,000 cycles to the long axis of the functional cusp of each of the teeth, which were immersed in a 1% methylene blue solution. The teeth were split in half, and the linear depth of dye penetration was evaluated according to the criteria. The results were analyzed using one-way ANOVA (p = 0.05) and Duncan's multiple range test. The results demonstrated that Caviton and MD-Temp showed significantly lower microleakage than IRM and ZOE. It was concluded that Caviton and MD-Temp exhibited better sealing ability than IRM and ZOE under dynamic loading.

• Journal of Korean Society of Archives and Records Management
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• v.20 no.1
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• pp.115-137
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• 2020

This study aims to examine the limitations of status that describe archives based on the Archival rules, and to propose a new method using the Records in Context - Conceptual model (RiC-CM) as a solution. Given this, the study conducted literature reviews and case studies. The solutions based on RiC-CM and its effects on the limitations of the existing environment are as follows. First, RiC-CM can describe multiple provenances about archives. This can be solved by defining individual records and provenances as "entity" and expressing their associations as relationships. The interrelation of entities alone can more accurately represent the information of provenances associated with a particular archive, making it easier to identify the overall context that makes records. Second, RiC-CM can link related files. Those that belong to a specific records group (fonds) can be resolved by assigning them to individual entities and making interrelation according to the context that makes records. This method makes it possible to serve information about the context that makes records. From the user's point of view, more options are available for searching records. Third, RiC-CM can link all relevant producer-made records related to a specific production organization. If organizations are related to each other, they can be defined as "entity," and their relationship can be expressed as "associated with." It helps to comprehensively examine the context of provenances. The findings of this study are expected to be used as a basis for future research on RiC-CM, in response to the paradigm shift for electronic records management systems.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.4
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• pp.52-65
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• 1984

In general precise estimation of hourly of daily distribution of the long-term run-off should be very important in a design of source of irrigation. However, there have not been a satisfying method for forecasting of stationar'y long-term run-off in Korea. Solving this problem, this study introduces unit-hydrograph method frequently used in short-term run-off analysis into the long-term run-off analysis, of which model basin was selected to be Sumgin-river catchment area. In the estimation of effective rainfall, conventional method neglects the Soil moisture condition of catchment area, but in this study, the initial discharge (qb) occurred just before rising phase of the hydrograph was selected as the index of a basin soil moisture condition and then introduced as 3rd variable in the analysis of the reationship between cumulative rainfall and cumulative loss of rainfall, which built a new type of separation method of effective rainfall. In next step, in order to normalize significant potential error included in hydrological data, especially in vast catchment area, Snyder's correlation method was applied. A key to solution in this study is multiple correlation method or multiple regressional analysis, which is primarily based on the method of least squres and which is solved by the form of systems of linear equations. And for verification of the change of characteristics of unit hydrograph according to the variation of a various kind of hydrological charateristics (for example, precipitation, tree cover, soil condition, etc),seasonal unit hydrograph models of dry season(autumn, winter), semi-dry season (spring), rainy season (summer) were made respectively. The results obtained in this study were summarized as follows; 1.During the test period of 1966-1971, effective rainfall was estimated for the total 114 run-off hydrograph. From this estimation results, relative error of estimation to the ovservation value was 6%, -which is mush smaller than 12% of the error of conventional method. 2.During the test period, daily distribution of long-term run-off discharge was estimated by the unit hydrograph model. From this estimation results, relative error of estimation by the application of standard unit hydrograph model was 12%. When estimating by each seasonal unit bydrograph model, the relative error was 14% during dry season 10% during semi-dry season and 7% during rainy season, which is much smaller than 37% of conventional method. Summing up the analysis results obtained above, it is convinced that qb-index method of this study for the estimation of effective rainfall be preciser than any other method developed before. Because even recently no method has been developed for the estimation of daily distribution of long-term run-off dicharge, therefore estimation value by unit hydrograph model was only compared with that due to kaziyama method which estimates monthly run-off discharge. However this method due to this study turns out to have high accuracy. If specially mentioned from the results of this study, there is no need to use each seasonal unit hydrograph model separately except the case of semi-dry season. The author hopes to analyze the latter case in future sudies.

• The KIPS Transactions:PartB
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• v.15B no.1
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• pp.45-52
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• 2008

As the recent development of the IT services, there is a urgent need of effective diagnosis system to present appropriate solution for the complicated problems of breakdown control, a cause analysis of breakdown and others. So we propose an intelligent diagnosis system that integrates the case-based reasoning and the artificial neural network to improve the system performance and to achieve optimal diagnosis. The case-based reasoning is a reasoning method that resolves the problems presented in current time through the past cases (experience). And it enables to make efficient reasoning by means of less complicated knowledge acquisition process, especially in the domain where it is difficult to extract formal rules. However, reasoning by using the case-based reasoning alone in diagnosis problem domain causes a problem of suggesting multiple causes on a given symptom. Since the suggested multiple causes of given symptom has the same weight, the unnecessary causes are also examined as well. In order to resolve such problems, the back-propagation learning algorithm of the artificial neural network is used to train the pairs of the causes and associated symptoms and find out the cause with the highest weight for occurrence to make more clarified and reliable diagnosis.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.16-27
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• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omni-directional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a reliable broadcast protocol in link taller based on directional antennas, named MDB(MAC protocol for Directional Broadcasting). This protocol makes use of DAST(Directional Antennas Statement Table) information and D-MACA(Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to resolve the many collision problem wit]1 omni-directional antenna. To analyze its performance, MDB protocol is compared with IEEE 802.11 DCF protocol [9] and the protocol 2 of reference [3], in terms of the success rate of broadcast and the collision rate. As a result of performance analysis through simulation, it was confirmed that the collision rate of the MDB protocol is lower than those of IEEE 802.11 and the protocol 2 of reference [3], and that the completion rate of broadcast of MDB protocol is higher than those of IEEE 802.11 and the protocol 2 of reference [3].