• Journal of Technology Innovation
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• v.6 no.2
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• pp.101-121
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• 1998

Recent entrepreneurship studies emphasize the importance of entrepreneurial activities of entrepreneurs. This study focuses entrepreneurial behaviors, especially entrepreneurial networking activities of Korean high-tech ventures. Networking activities can utilize external resources which are critical to success, with less resource commitment. This study examines the relationship between characteristics of entrepreneurial networking and performance, and analyses influencing factors of entrepreneurial networking activities. Based on the data from 55 new high-tech ventures in Korea, hypotheses that the characteristics of entrepreneurial networking are related to the performance of new high-tech ventures are tested using regression analysis and t-test. Major findings of this study are as follows: (1) entrepreneurial networking are related to the performance of new high-tech ventures, (2) significant differences are found in the characteristics of entrepreneurial networking between high- and low-performance firms, (3) characteristics of entrepreneurs and firm' technological capabilities are related to the degree of entrepreneurial networking activities. Finally, managerial and policy implications of the study are presented and future research directions are also suggested.

• The Mathematical Education
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• v.59 no.4
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• pp.295-312
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• 2020

This study aimed to investigate and compare perceptions of middle and high school mathematics teachers on assessment. For the purpose, we developed and used a survey consisting of two parts(importance/performance on assessment and general opinion on process-based assessment). We gathered data from 188 middle school and 125 high school mathematics teachers in Incheon area. An Importance-Performance Analysis(IPA) method was used for data analysis. As results, middle school mathematics teachers showed higher perception on both importance and performance in almost all area on assessment than high school teachers. In addition, research results based on teaching experience indicated that mathematics teachers having more teaching experience seemed to perceive high importance-high performance and low importance-low performance tasks more than mathematics teachers having less experience. In particular, middle school teachers recognized many low importance-high performance tasks according to their teaching experience. The IPA gave us different results depending on the school size. The larger the school, the more diverse opinions appeared tasks in low importance-high performance. From the general opinion on process-based assessment, the middle school mathematics teachers also seemed to have more positive perspectives and to be more active in assessment than high school mathematics teachers. Finally, we discuss implications for future policy formulation and implementation on process-based assessment.

• Journal of the Korean Society for Advanced Composite Structures
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• v.4 no.3
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• pp.22-29
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• 2013

In recent years, the construction of high-rise buildings are promoted. According to these, there are many needs about new technologies to strengthen the building performance and high-strength steel is regarded as one of these for promoting building performance. In Korea, high-strength steels which stress are over 600MPa are on market and in aborad, super high-strength steels over 1000MPa are developing and they expected to promote the building performance. But there are still doubts about applying high-strength steel members because of size effect and worry of brittle fracture. In this reports, we propose results of performance and analysis tests for use with general steel. We propose the characteristic of high-strength steels first and next the results of performance test to show they satisfy the performance that designers expect. And last, we compare the results of test and analysis for acquire the alanysis reliability in non-linear analysis with high-strength steels.

• Journal of Labour Economics
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• v.32 no.2
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• pp.27-60
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• 2009

Some fact-findings which were gained as results of regression analysis with Workplace Panel Survey data about whether Employee Participatory High Performance Work Practices could help to increase the compensation of workers are as followings. Firstly. though High Performance Work Practices wert generally estimated to have positive effects on management performance of establishments, their positive effects were not so significant except in cases of some practices. Secondly, the wage increase effects of the main High Performance Work Practices were much stronger with statistical significance. Thirdly. in case of unionized establishments. the wage increase effects of the main High Performance Work Practices were estimated to be much stronger than in the Don-unionized.

• Journal of the Korean Society for Railway
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• v.6 no.2
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• pp.100-107
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• 2003

This paper presents development of train performance simulation(TPS) program to analyze traction performance, braking performance and energy consumption for Korea high speed railway system. The conventional TPS program have some inconveniences such as DOS-based platform, user interface and limited function. The simulation technique model using scenario menu, various analysis function and object-oriented design/programming is presented. This simulation result have been compared with Alstom's for the Seoul-Pusan High Speed Rail Project.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.35-36
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• 2016

Recently, with the increasing demand of high performance of concrete, the mix design of concrete mixture has became low water-to-binder ratio with high binder content. To compensate these trend of mix design, high range water reducer, or superplascizier has been invented to achieve high flowable concrete. Although this superplasticizer provides favorable workability based on its dispersing action on the components of concrete mixture, it has an limitation of decreasing viscosity of the mixture, and thus it is difficult to secure sufficient workability for high performance concrete mixtures with high binder content. To improve the workability of concrete with high viscosity, recently, low-viscosity type superplasticizer was introduced, and in this research, a fundamental properties of low-viscosity type superplasticizer is evaluated.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.461-464
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• 2006

Recently, as structures become bigger and higher, it is needed that high strength, high flow and high durability concrete. Demanding of High performance concrete that equality is maintained without material separation while flow, strength is increased by using low W/C rate and admixture, carbonation does not occur because of dense filling and has high durability is increasing rapidly. Because this high performance concrete is superior to general concrete in workability and durability, it is widely used in many construction and engineering works fields. However, it is reported that when it was exposed in fire, violent explosive spalling would be happened. Therefore, the purpose of this study evaluates explosive spalling properties of fire damaged high performance concrete according to the heating time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.94-95
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• 2020

This paper introduces the mix design and performance evaluation of Ultra-High Performance Concrete (UHPC). The concrete mixture is designed to achieve a densely compacted cementitious matrix via the modified Andreasen & Andersen particle packing model. The compressive strengths of UHPC designed by this method reached 154MPa. The relationship between packing theory and compressive strength of UHPC is discussed in this paper.

• Journal of Communications and Networks
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• v.17 no.4
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• pp.370-383
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• 2015

Effective link quality estimation is a vital issue for reliable routing in wireless networks. This paper studies the performance of expected transmission count (ETX) under different traffic loads. Although ETX shows good performance under light load, its performance gets significantly worse when the traffic load is high. A broadcast packet storm due to new route discoveries severely affects the link ETX values under high traffic load, which makes it difficult to find a good path. This paper presents the design and implementation of a variation of ETX called high load - ETX (HETX), which reduces the impact of route request broadcast packets to link metric values under high load. We also propose a reliable routing protocol using link quality metrics, which is called link quality distance vector (LQDV). We conducted the evaluation of the performance of three metrics - HETX, ETX and minimum hop-count. The simulation results show that HETX improves the average route throughput by up to 25% over ETX under high traffic load. Minimum hop-count has poor performance compared with both HETX and ETX at all of the different traffic loads. Under light load, HETX and ETX show the same performance.

• Computers and Concrete
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• v.33 no.3
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• pp.309-324
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• 2024

Internal curing, a widely used method for mitigating early-age shrinkage in concrete, also offers notable advantages for concrete durability. This paper explores the potential of internal curing by partial replacement of sand with fine lightweight aggregate for enhancing the behavior of high-performance concrete at elevated temperatures. Such a technique may prove economical and safe for the construction of skyscrapers, where explosive spalling of high-performance concrete in fire is a potential hazard. To reach this aim, the physico-mechanical features of internally cured high-strength concrete specimens, including mass loss, compressive strength, strain at peak stress, modulus of elasticity, stress-strain curve, toughness, and flexural strength, were investigated under different temperature exposures; and to predict some of these mechanical properties, a number of equations were proposed. Based on the experimental results, an advanced stress-strain model was proposed for internally cured high-performance concrete at different temperature levels, the results of which agreed well with the test data. It was observed that the replacement of 10% of sand with pre-wetted fine lightweight expanded clay aggregate (LECA) not only did not reduce the compressive strength at ambient temperature, but also prevented explosive spalling and could retain 20% of its ambient compressive strength after heating up to 800℃. It was then concluded that internal curing is an excellent method to enhance the performance of high-strength concrete at elevated temperatures.