• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.370-377
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• 2004

The density approach and the homogenization design method are representative methods in topology optimization problems. In the topology optimization in magnetic fields, those methods are applied based on the results of the applications In elastic fields. In this study, the density method is modified considering the concept of the homogenization design method. Also, the results of the topology optimization in magnetic fields by the modified density method as well as the homogenization method are compared especially focusing the change of the penalization parameter in the density approach. The effect of the definition of the design domain such as global/local design domain is also discussed.

• Structural Engineering and Mechanics
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• v.3 no.3
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• pp.245-253
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• 1995

A combination of Riccati transfer matrix method and finite element method is proposed for obtaining vibration frequencies of structures. This method reduces the propagation of round-off errors produced in the standard transfer matrix method and finds out the values of the frequency by Newton-Raphson method. By this technique, the number of nodes required in the regular finite element method is reduced and therefore a microcomputer may be used. Besides, no plotting of the value of the determinant versus assumed frequency is necessary. As the application of this method, some numerical examples are presented to demonstrate the accuracy as well as the capability of the proposed method for the vibration of structures.

• Journal of Korean Home Economics Education Association
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• v.15 no.1
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• pp.15-32
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• 2003

This study examined teacher perception of the instructional method. activities and material in terms of class quality enhancement. Also this study established instructional method. activities and material application Per 7th Practical Arts Education Course guidance domain. and type identification of the instructional method and activities unique to the Practical arts curriculum. Conclusions : 1. Teachers consider the instructional method and material beneficial. However in the item relevant to application of diverse instructional methods Per specific teaching objective and educational content in the actual classroom. the highest percentage responding. ‘relatively yes’ (39.7%) . balanced out with those answering. ‘no’(37.7%) 2. In linking the instructional method and material to secondary school home economics education, teachers experienced difficulty in teaching only the clothing education domain . 3. In each guidance domain, lecture method, problem-solving learning. cooperative learning. home project learning and functional learning were surveyed for instructional method suitability. Notably, home project learning was identified as a significant instructional method. This result begs in-dept analysis as home project learning may be utilized as a tool to compensate for the absence of practical educational objective condition fulfillment and to substitute for teachers unable to Provide such functional guidance in class. 4. In each guidance domain. role-playing. debate/discussion. case study research, practical exercise and activity reporting were rated as essential teaching ㆍ learning activities. 5. In each guidance domain.‘VCR’, ‘CD-ROM’ and ‘Web media’ were identified as suitable instructional materials .

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.2
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• pp.91-100
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• 2006

The purpose of this study was to validate alternative method by using non-carcinogenic, and less toxic solvents than NIOSH analytical method 5524 for measuring the airborne MWFs in workplaces. In laboratory tests, the ETM solvents(mixture of same volume for ethyl ether, toluene, and ethanol) were selected. The alternative method of analyzing MWFs, referred to as the ETM solvent extraction method, showed 0.04 mg/sample as LOD, and 0.15 mg/sample as LOQ. The analytical precision (pooled CV, coefficient of variation) of the ETM solvent extraction method for analyzing the straight, soluble, semisynthetic, and synthetic metalworking fluid was 1.5%, 2.0%, 2.6%, 1.6%, respectively, which was similar to the precision (2.6%) of NIOSH analytical method (NIOSH 0500) for total dust. The analytical accuracy by recovery test, spiked mass calculated as extractable mass, was almost 100%. As the result of storage stability test, metalworking fluid samples should be stored in refrigerated condition, and be analyzed in two weeks after sampling. The 95% confidence limit of the estimated total standard error for the ETM solvent extraction method for analyzing the straight, soluble, semisynthetic, and synthetic metalworking fluid was ${\pm}12.6%$, ${\pm}12.5%$, ${\pm}14.0%$, and ${\pm}13.6%$, respectively, which satisfied the OSHA sampling and analytical criteria.

• Korean Journal of Veterinary Research
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• v.23 no.1
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• pp.105-110
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• 1983

The studies carried out to investigate the detection method of Fasciola eggs from positive cattle feces in the intradermal reaction method with laborsaving composition of sieves and Kim's sedimental tube method. The results obtained are summarized as follows: 1. The detection method of Fasciola eggs was improved by 3 meshes (100mesh, 150mesh, 250mesh) for filteration of fecal fluid contained Fasciola eggs. 2. Third type of tube in the 3 kinds of sedimental tube had the highest recovers rate of Fasciola eggs. Thus, this type of tube was selected and called as Kim's sedimental tube. 3. A-II, A-III, B-III and C-III type by Kim's sedimental tube method had the recovery rates of eggs in the 1st drop as ranged 99 to 100% and, A-I, B-II, C-II as 71 to 91%. 4. These Type of tubes were useful to detect Fasciola eggs and to shorten the time of the diagnostic procedures. 5. The Kim's sedimental tube method showed high recovery rates and convenient procedures as compared with other detection methods reported. In addition, the EPG value can also be obtained by this method. Therefore, it is desirable that the Kim's sedimental tube method could be recommended to clinicians.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.391-396
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• 2013

As the construction environment has been changing all the times, the techniques for managing the construction projects have been improved accordingly. The schedule management technique, one of the construction management tools, has been evolved as well in order to be adaptable to new construction environment. Most of newly proposed scheduling techniques have been based on the Critical Path Method (CPM) that was proposed in 1956. The CPM is classified into two categories, Arrow Diagramming Method (ADM) and Precedence Diagramming Method (PDM). ADM is so good in the visual format but it cannot express the overlapping relationships between two consecutive activities. On the other hand, PDM can express the overlapping relationships but it is unsatisfactory in the visual format. Recently, as the construction environment becomes more complex and the role of schedule management becomes more and more important, the overlapping expression becomes one of critical factors for scheduling as well. Most of construction project participants prefer more comfortable visual format, however, the scheduling software based on the PDM cannot satisfy their basic requirement. Beeliner, new scheduling software based on the Beeline Diagramming Method (BDM) that was proposed in 2010, was developed in 2012, it can express more flexible overlapping relationships and has superior visual format as well. This paper presents major features and applications of Beeliner, and makes construction professionals understand new scheduling concept and its applications.

• Bulletin of the Society of Naval Architects of Korea
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• v.25 no.1
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• pp.11-20
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• 1988

From the engineering point of view, a synthesis as well as an analysis technique is explored to search for the improved design of grillage which is common in ship structure. As an approximate analysis method for the grillage, an interaction reaction method is developed and compared with the finite element method. It is found that the discrepancy between these two methods is so negligible that the percent method could be used effectively for the grillage analysis. As an optimization technique, a feasible direction method could be used is combined with the intersection reaction method in order to design a minimum weight optimal grillage. The feasible direction method shows a good numerical performance although it requires more calculation times compared with the direct search method. Finally, the application of multiple objective optimization method to grillage is investigated in order to resolve conflicts existed between the multiple objectives which is a common characteristic of structure design problem. Goal programming method is extended to handle a nonlinear property of constraints and objective functions. It seems that the nonlinear goal programming could help not only to establish a relative importance of each objective, but also enable the designer to choose the best combination of design variables.

• Steel and Composite Structures
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• v.52 no.1
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• pp.31-43
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• 2024

A very widely used analytical method (mathematical model), mentioned in Eurocode 3, to examine the connections' bending behavior is the component-based method that has certain weak points shown in the plastic behavior part of the moment-rotation curves. In the component method available in Eurocode 3, for simplicity, the effect of strain hardening is omitted, and the bending behavior of the connection is modeled with the help of a two-line diagram. To make the component method more efficient and reliable, this research proposed its advanced version, wherein the plastic part of the diagram was developed beyond the guidelines of the mentioned Regulation, implemented to connect the end plate, and verified with the moment-rotation curves found from the laboratory model and the finite element method in ABAQUS. The findings indicated that the advanced component method (the method developed in this research) could predict the plastic part of the moment-rotation curve as well as the conventional component-based method in Eurocode 3. The comparison between the laboratory model and the outputs of the conventional and advanced component methods, as well as the outputs of the finite elements approach using ABAQUS, revealed a different percentage in the ultimate moment for bolt-extended end-plate connections. Specifically, the difference percentages were -31.56%, 2.46%, and 9.84%, respectively. Another aim of this research was to determine the optimal dimensions of the end plate joint to reduce costs without letting the mechanical constraints related to the bending moment and the resulting initial stiffness, are not compromised as well as the safety and integrity of the connection. In this research, the thickness and dimensions of the end plate and the location and diameter of the bolts were the design variables, which were optimized using Particle Swarm Optimization (PSO), Snake Optimization (SO), and Teaching Learning-Based Optimization (TLBO) to minimization the connection cost of the end plate connection. According to the results, the TLBO method yielded better solutions than others, reducing the connection costs from 43.97 to 17.45€ (60.3%), which shows the method's proper efficiency.

• Journal of Environmental Health Sciences
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• v.22 no.2
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• pp.32-42
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• 1996

This study was performed to evaluate accuracy and precision of filter method and impinger method for analyzin airborne isocyanates in mixture (2, 6-TDI, HDI, 2, 4-TDI, MDI). Filter method was performed using the OSHA Method 42 and impinger method using the NIOSH Method 5521. The samples were analyzed by high performance liquid chromatography-ultraviolet detector (HPLC-UVD). After the optimum operating conditions for each method were investigated, samples with various concentration levels were quantified at the conditions. The precision was expressed by the pooled coefficient of variation(C.V.) and the accuracy by overall accuracy. The results are summarized as follows: 1. The optimum condition of filter method was determined at 35/65 ACN/buffer (0.01 M ammonium acetate) in mobile phase. And in case of impinger method, it was at 30/70 ACN/buffer(0.2 M sodium acetate). The effect of concentrations of acetate on the separation of the peaks was not significant, but, the effect of ACN/buffer ratio was significant. 2. The correlation coefficients for the two methods were above 0.9 in all isocyanate compounds. Average recovery efficiencies for 2, 6-TDI, HDI, 2, 4-TDI and MDI in filter method were 92.4%, 102.6%, 87.3% and 101.0%, respectively. Those in impinger method were 106.6%, 106.7%, 99.0% and 103.6%, respectively. As a result, the recovery efficiency of impinger method was higher than those of filter method in analyzing isocyanate compounds. 3. The pooled coefficients of variations of the methods were slightly higher than expected. The overall accuracies of the methods were within $\pm 25%$ for each isocyanate compound. Since these results satisfy NIOSH criteria, the accuracy of the experiment is appropriate. 4. As seen above, impinger method is more efficient than filter method. But, there are many disadvantages in impinger method. Therefore, solid sorbent such as a glass fiber filter must be developed in order to have the high efficiency not less than that of impinger method in the future.

• Management Science and Financial Engineering
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• v.13 no.1
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• pp.1-24
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• 2007

I propose new combined randomized methods for global optimization problems. These methods are based on the Nested Partitions(NP) method, a useful method for simulation optimization which guarantees global optimal solution but has several shortcomings. To overcome these shortcomings I hired various statistical selection methods and combined with NP method. I first explain the NP method and statistical selection method. And after that I present a detail description of proposed new combined methods and show the results of an application. As well as, I show how these combined methods can be considered in case of computing budget limit problem.