• Journal of Environmental Health Sciences
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• v.47 no.2
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• pp.166-174
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• 2021

Objectives: This study aimed to provide temporal Acute Exposure Guideline Levels (AEGL) for a hazardous substance as a pilot study. Methods: As one of the substances designated by the Korea Ministry of Environment as requiring preparations for potential accidents, formaldehyde was selected to estimate the AEGLs. The calculation was based on Haber's formula (Cn×t=k) using valid toxicity data (for humans/animals). A total of 96 points of AEGL levels were provided using an interval of five minutes over eight hours. Results: The AEGL-1 and 2 values were constant for the entire exposure duration at 0.9 ppm and 14 ppm, respectively. The values were obtained from clinical/animal tests, and the adaptation effect after a given exposure duration was also considered. AEGL-3 was based on animal toxicity data, and it was estimated from 127 ppm for the initial five minutes to 35 ppm for eight hours. Conclusions: More specific AEGL levels for formaldehyde could be obtained in this study using toxicity data with Haber's formula. Based on this methodology, it would be also possible to estimate AEGL levels that can be used at the scene of a chemical accident for other substances requiring preparation for potential accidents.

• Journal of the Korean Ceramic Society
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• v.34 no.9
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• pp.979-985
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• 1997

The three-dimensional particle packing process is simulated using Lahey FORTRAN 90 as a programming language running on a personal computer. Particle clusters constructed with rearrangement which occurs during packing have higher average coordination number and packing density than particle clusters rearranged after packing. Rearranging particles can not completely block other particles from entering pore volume in 3-dimensional packing unlike in 2-dimensional packing. It is found that there is a region of instability where lower packing density results from the destruction of the ordered packing.

• Journal of Power Electronics
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• v.9 no.6
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• pp.892-902
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• 2009

This paper deals with the dynamic voltage control problem at the inverter end of a HVDC link when connected to a weak AC system which has the potential for harmonic instability and commutation failures. The dynamic voltage control problem is tackled with a STATCOM (Static Compensator), which not only provides a rapid recovery from harmonic instability and commutation failures but also offers a lower cost filter design for HVDC systems. PSCAD/EMTDC simulations are presented to validate the proposed topology and to demonstrate its robust performance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1986.06a
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• pp.1-9
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• 1986

Since my arrival on March 15, 1986 I can only give an overview of several topics which I think might stimulate ideas and questions from the members of this technical organization. These topics will include some thoughts about the Korean automotive industry, future needs regarding manpower and cooperation among manufacturers, the oil industry and the government. Korea is experiencing a tremendous growth not only in the export market but also in domestic sales of motor vehicles. This expansion will require trained manpower in many areas of expertise. This growth in technology and manpower will require a great degree of coordination and cooperation between companies and government to reduce duplication, minimize costs and reduce reliance on foreign technology.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.153-155
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• 2000

This paper reveals some correlations between LDC voltage control method and the output of DGS, and also presents a method for determining the amounts of real, reactive Power of DGS for proper voltage regulation of power distribution system with LDC. Proposed method has been applied to a 22.9 kV class power distribution system, and those results show that the distribution system voltage profile is improved.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1088-1095
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• 1999

This paper presents short-term hydro scheduling method for hydrothermal coordination by genetic algorithms. Hydro scheduling problem has many constraints with fixed final reservoir volume. In this paper, the difficult water balance constraints caused by hydraulic coupling satisfied throughout dynamic decoding method. Adaptive penalizing method was also proposed to handle the infeasible solutions that violate various constraints. In this paper, we proposed GA to solve hydrothermal scheduling with appropriate decoding method and dynamic penalty method. The effectiveness of the proposed method is demonstrated in the case study.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.751-756
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• 2001

Permanent-Form is one of system forms for reducing human labor, work costs, oscillation, noise, construction wastes and so on. Permanent-Form is made from precast method in facilities. and carried in construction site to assemble with no demolding. The biggest expense to produce Permanent-Form is about manufacturing mold. To satisfy various size of building member, the same number of manufacturing mold is needed. In this paper, studied about manufacturing mold module for acquiring economic merit and construction member safety. Permanent-Form is member stress and structural analyzed if temporary equipment were used. The result of this study is below. (1) Column sizes of Permanent-Form are 47 kinds of prototype that based on Modular coordination's basic module. 4 pieces or 6 pieces are composed basically. (2) For beam size modular coordination, standard height and width of beam are 150mm and 100mm. It brings 24 kinds of prototype. 4 pieces or 5 pieces are composed basically. (3) Structural analysis value of modular member is like this Column member shows 9.4 to 85kgf/$cm^{2}$ stress distribution and beam member shows 6.3 to 95kgf/$cm^{2}$ stress distribution. Constructing permanent form could have structural safety with use of temporary equipment

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.3
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• pp.540-552
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• 2010

This research forms preliminary data for the coordination of environmental color planning in industry through a color analysis of work clothes and the work environment. A digital camera was used to study the work environment of two major shipbuilding companies located in Geoje city and Goseong county. The picture data was analyzed as G (ground: environment) and F (figure: clothes), and analyzed hue, value, and the chroma value through a Muncell conversion 9.0.6 from the color cluster, number of pixel, and RGB value. The results are as follows: First, GY, Y color were mostly used in the shipbuilding environment and work clothes. The color value was used in a relatively wide range but very low chroma (0-3), dark grayish, grayish tone dominated both fields. Second, the use of limited colors cannot be secured for safety in attention of the shipbuilding field. Third, unclear and vogue colors lessened the optical tiredness of workers that helped in the prevention of industrial accidents. Color combination and color selection should be considered for a secure safety color coordination between work clothes and the work environment when it comes to complicated color principles.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.9-19
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• 2016

Accurate models of the characteristics of typical inverse-time overcurrent (OC) protective devices play an important role in the protective coordination schemes. This paper presents a novel approach to determine the OC protective device parameters. The approach is based on the Eigensystem Realization Algorithm which generates a state space model to fit the characteristics of OC protective devices. Instead of the conventional characteristic curves, the dynamic state space model gives a more exact fit of the OC protective device characteristics. This paper demonstrates the feasibility of decomposing the characteristic curve into smooth components and oscillation components. 19 characteristic curves from 13 typical and 6 non-typical OC protective devices are chosen for curve-fitting. The numbers of fitting components required are determined by the maximum absolute values of errors for the fitted equation. All fitted equations are replaced by a versatile equation for the characteristics of OC protective devices which represents the characteristic model of a novel flexible OC relay, which in turn may be applied to improve the OC coordination problems in the sub-transmission and distribution systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.4
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• pp.1359-1375
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• 2015

Energy efficiency is critical for Wireless Sensor Networks (WSNs) since sensor nodes usually have very limited energy supply from battery. Sleep scheduling and nodes cooperation are two of the most efficient methods to achieve energy conservation in WSNs. In this paper, we propose an adaptive energy optimization approach for target tracking applications, called Energy-Efficient Node Coordination (EENC), which is based on the grid structure. EENC provides an unambiguous calculation and analysis for optimal the nodes cooperation theoretically. In EENC, the sleep schedule of sensor nodes is locally synchronized and globally unsynchronized. Locally in each grid, the sleep schedule of all nodes is synchronized by the grid head, while globally the sleep schedule of each grid is independent and is determined by the proposed scheme. For dynamic sleep scheduling in tracking state we propose a multi-level coordination algorithm to find an optimal nodes cooperation of the network to maximize the energy conservation while preserving the tracking performance. Experimental results show that EENC can achieve energy saving of at least 38.2% compared to state-of-the-art approaches.