• Title/Summary/Keyword: BIG4

Search Result 3,614, Processing Time 0.031 seconds

A Study on the Daylighting Transmittance Efficacies of Skylights by Calculating the Effective Transmittance of Light Well (광정의 유효투과율에 의한 천창 형태별 주광의 투과효율 평가)

  • Kim, Chang-Sung
    • KIEAE Journal
    • /
    • v.12 no.2
    • /
    • pp.53-58
    • /
    • 2012
  • Daylight is one of the most critical factors that can be utilized for architectural spaces; compared to artificial light, it is a sustainable energy source without the cost of electric energy and offers a more natural feeling to the visitors in the building. To make the space quality better, many architects have tried to predict daylight performance during the design process. The aim of this study is to evaluate the daylight transmittance efficacies of the five shapes - Flat, Pyramid, Dome, Barrel Vault. Ridge - of skylights. The results of this study indicated that the differences of transmittance efficiency among various skylights were less than 4.6% except the flat shaped skylight. Therefore, this study shows that there were no big differences of the daylight transmittance efficacies among the shapes of skylights.

On Retraining Programs for Cuisiniers (조리사의 재교육 프로그램에 관한 연구)

  • Choi, Young-Joon
    • Culinary science and hospitality research
    • /
    • v.14 no.4
    • /
    • pp.27-40
    • /
    • 2008
  • This study focused on retraining programs for cuisiniers and drawing attention to the necessity of retraining and the new method of retraining for cuisiniers as a professional in a knowledge based society. Case study review and interviews followed by thorough review of related literatures were taken place to give suggestions and comments for the improvement of job performance enhance training for cuisiniers. Interviews were done with current participants and institutional trainers in March, 2008. Result from the interviews showed that retraining was really necessary. It was concluded that various retraining programs organized and developed by an association could be the solution. Methods of retraining can take formats of distance learning, classroom learning, and blended learning. However, working condition for most cuisiniers at present would allow them to squeeze some time off to attend higher education and most restaurant companies are not big enough to offer systematic job training on site or not stable enough to arrange replacement workers. It is therefore suggested to adopt a blended learning method and further study on this subject is highly recommended.

  • PDF

Drone Simulation Technologies (드론 시뮬레이션 기술)

  • Lee, S.J.;Yang, J.G.;Lee, B.S.
    • Electronics and Telecommunications Trends
    • /
    • v.35 no.4
    • /
    • pp.81-90
    • /
    • 2020
  • The use of machine learning technologies such as deep and reinforcement learning has proliferated in various domains with the advancement of deep neural network studies. To make the learning successful, both big data acquisition and fast processing are required. However, for some physical world applications such as autonomous drone flight, it is difficult to achieve efficient learning because learning with a premature A.I. is dangerous, cost-ineffective, and time-consuming. To solve these problems, simulation-based approaches can be considered. In this study, we analyze recent trends in drone simulation technologies and compare their features. Subsequently, we introduce Octopus, which is a highly precise and scalable drone simulator being developed by ETRI.

Small-scale Features of Thermal Inflation: CMB Distortion, Substructure Abundance, and 21cm Power Spectrum

  • Hong, Sungwook E.;Zoe, Heeseung;Ahn, Kyungjin;Cho, Kihyun;Stewart, Ewan D.
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.42 no.2
    • /
    • pp.78.4-79
    • /
    • 2017
  • Thermal inflation is an additional inflationary mechanism before the big bang nucleosynthesis, which solves the moduli problem and naturally provides a plausible dark matter candidate. Thermal inflation leaves a slight enhancement followed by huge suppression of a factor of ~50 in the curvature and matter power spectrum, which can be expressed in terms of a single characteristic scale $k_b$. Here we describe the observability of the small-scale features of thermal inflation from various observations, such as CMB distortion, satellite galaxy abundance in the Milky-Way-sized galaxies, and 21-cm power spectrum before the epoch of reionization.

  • PDF

A study on grinding and process design of Constant Velocity (등속조인트의 공정설계 및 연삭에 관한 연구)

  • Kim, Woo-Kang;Ko, Jun-Bin;Byun, Dong Hae
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.9 no.4
    • /
    • pp.8-13
    • /
    • 2010
  • The constant velocity internal grinding is a popular process for studying axle machine design and process in automobile industry. In this study, The program which gives the data of wheel size and truing diameter of ball groove is developed. As a result I obtained the data of grinding conditions makes good surface roughness get a grinding conditions. The grinding characteristics and conditions of constant velocity joint were investigated with respect to grinding feed, cutting depth, grinding time. At machine failure, the results were suddenly increased and the detailed surfaces were extremely obtained. Grinding condition was big more affected by grinding depth, grinding speed and grinding time.

Design and Performance Test of Plate Type ER-Valve (평판형 ER-Valve의 제작 및 성능실험)

  • 장성철;염만오
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.12 no.6
    • /
    • pp.29-35
    • /
    • 2003
  • In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-valves are measured with varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. If we allow the same electric field in the ER-Valve, we came to how that the pressure drop is effected by the electrode length and electrode width. When the strength of the electric field increased, the pressure drop happened big and the flow rate decreased.

Mechanical Seal의 이상설계 감시에 관한 연구

  • 임순재;최만용;남궁석
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1992.10a
    • /
    • pp.166-171
    • /
    • 1992
  • Mechanical seals are generally used in the fields of industries as sealing devices. The failure of mechanical seals like crack, leakage, breakage fast and severe wear, excessive torque, and squeaking result in big problems. For the development of monitoring system, this study was carried out to identify abnormal phenomina on alumina(AI $\_$2/ O /sub3/) seal ring and resin bonded carbon ring, and to propose the proper parameter for monitoring failure on mechanical seals. Sliding were tests are conducted at 12 experimental conditions that contains 3 different contact pressure and 4 surface conditions. Torque, temperature, and acoustic emission are measured. Optical microstructure and scanning electron microscopy are observed for the wear processing every 10 minute sliding at rotation speed of 1750 RPM.

A Study on the Development of a Compact Gun Drill Machine (소형 Gun Drill Machine 개발에 관한 연구)

  • Oh, Jin-Soo;Kang, Dong-Myeong;Park, Kwang-Hoon;Namkoong, Chai-Kwan;Woo, Chang-Ki
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.16 no.4
    • /
    • pp.58-63
    • /
    • 2007
  • A compact gun drill machine was developed to improve productivity and economical efficiency for small and medium enterprise tool makers. Gun drilling works are mainly using at molding, automobile, aircraft industry and special tool makers to make deep holes. As gun drill machines are very expensive and big burden for small tool makers, so that works used to execute through outside orders but it was required lot of cost too. Most of gun drill machines are providing for high volume and large capacity enterprises. In order to use for small and medium enterprises that compact gun drill machine was designed and developed. It could be improved product quality, productivity and manufacturing cost for small and medium enterprises by using this machine.

Model Plants in Marine Biotechnology

  • Saga, Naotsune;Endo, Hirotoshi
    • Journal of Marine Bioscience and Biotechnology
    • /
    • v.4 no.1
    • /
    • pp.11-14
    • /
    • 2010
  • The genus Porphyra, consisting of 133 species includes several economically valuable species (i.e. P. yezoensis, P. tenera, P. pseudolinearis etc.). They are predominantly consumed and cultivated in East Asian countries such as Japan, Korea and China, and they are regarded as a big commercial market today. In addition to the industrial importance, P. yezoensis is currently regarded as a feasible candidate for a model plant in marine biotechnology, therefore there are a wide range of studies being undertaken: strain-preservation, development of mutant strains and genetic analysis and exhaustive molecular analysis including EST and macro/micro array. Focusing on the activities of our research group, current situation and future perspectives in marine biotechnological studies using P. yezoensis will be discussed in this mini review.

  • PDF

A Study on the Global Marketing Strategies in EC Environment (전자상거래 환경에서의 무역마케팅 전략에 관한 연구)

  • Kang Young-Ku;Hwang Sang-Gyu
    • Management & Information Systems Review
    • /
    • v.13
    • /
    • pp.1-26
    • /
    • 2003
  • As a very rapid diffusion of internet business in these days, the marketing mix strategies become more important matters. In addition, because of changes in international trade patterns, and an increase of internet users, new marketing strategies are needs. There's not a business in the world that shouldn't feel threatened by the internet, but companies willing to become engaged should find big opportunities. Becoming engaged with the internet, for matters, means understanding the unique nature of the internet market and using that understanding to execute dynamic strategies. This paper is focusing the analysing the difference between the internet marketing and traditional marketing and proposing the new strategical marketing mix. In the traditional marketing environment, 4P(Product, Price, Promotion, Place) is very important, but in the internet business environment 6C(Community, Connection, Commerce, Communication, Customization, Contents) is more important.

  • PDF