• Wind and Structures
• /
• v.5 no.2_3_4
• /
• pp.379-392
• /
• 2002

Numerical flow computations around an aeroelastic 3D square cylinder immersed in the turbulent boundary layer are shown. Present computational code can be characterized by three numerical aspects which are 1) the method of artificial compressibility is adopted for the incompressible flow computations, 2) the domain decomposition technique is used to get better grid point distributions, and 3) to achieve the conservation law both in time and space when the flow is computed a with moving and transformed grid, the time derivatives of metrics are evaluated using the time-and-space volume. To provide time-dependant inflow boundary conditions satisfying prescribed time-averaged velocity profiles, a convenient way for generating inflow turbulence is proposed. The square cylinder is modeled as a 4-lumped-mass system and it vibrates with two-degree of freedom of heaving motion. Those blocks which surround the cylinder are deformed according to the cylinder's motion. Vigorous oscillations occur as the vortex shedding frequency approaches cylinder's natural frequencies.

• Journal of the Korean Institute of Rural Architecture
• /
• v.14 no.1
• /
• pp.75-82
• /
• 2012

Today, educational facilities are considered to be one of the most important built environment. And the appropriate combinations and applications of technical elements related to green building on the education facilities are emphasized and demanded. These are must be compatible with the occupants' activities and their needs. The objective of this research is to identify and analyze of green building technologies, based on Green Educational Facilities' Case Study in Korea, USA, and Japan. As a result of the comparative analysis of this research, the green technological approaches, problem, and characteristics on educational facilities in different area, climate zone are identified and analyzed by external environment, energy, materials and resources, and indoor environment. It is useful as basic reference for future green educational facilities' planning and design in Korea.

• KIEAE Journal
• /
• v.4 no.3
• /
• pp.45-52
• /
• 2004

The purpose of this research was to identify the structural characteristics of open housing typologically and systematically. The main method of this study was content analysis and literature review on open housing. This study found that the typological analysis on terminology and the details of the constituents concerning structural patterns in open housing indicated that the main approaches were classified into three criteria such as 'Organization Element', 'Construction Element', and 'Equipment Element'. Organization Element was classified into 'Main Dwelling Unit Area and its Form', 'Room Organization Method', 'Relationship with the Main Dwelling Unit's External Constituents', and 'Combination Method of Support and Infill'. Construction Element was classified into 'Method of Structure' and 'Structural Element Technology'. Equipment Element was classified into 'Method of Using Duct' and 'Wet Zone Method'. The attributes were determined based on these classifications. The results of this study can be used to construct an evaluation tool and further to develop a framework in understanding open housing. Technical research should be conducted on the variables that affect the flexibility of space.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.2
• /
• pp.149-156
• /
• 2018

In this technical note, I report the analysis of electrochemical impedance data measured with potential sweeping. Even though the instruments for voltammetric impedance measurements have been developed for decades using different approaches, their applications are limited due to the lack of well-established protocols to easily analyze voltammetry data. To fill this gap, the singular point of the specific potential is considered that is only determined by the standard/formal potential and the transfer coefficient and is independent of the kinetics and experimental parameters (including revertability) of faradaic reactions. Taking the advantage of its inertness, I suggest an approach employing the singular point as a reference to obtain general electrochemical information. As all the concepts and methods are verified with numerical simulations, this technique is expected to be applied for complex reactions involving electrochemical and chemical reaction mechanisms.

• Journal of Genetic Medicine
• /
• v.12 no.2
• /
• pp.61-65
• /
• 2015

Whole genome sequencing (WGS)-based noninvasive prenatal test (NIPT) is the first method applied in the clinical setting out of various NIPT techniques. Several companies, such as Sequenom, BGI, and Illumina offer WGS-based NIPT, each with different technical and bioinformatic approaches. Sequenom, BGI, and Illumina utilize z-, t-, and L-scores, as well as normalized chromosome values, respectively, for trisomy detection. Their outstanding performance has been demonstrated in clinical studies of more than 100,000 pregnancies. The sensitivity and specificity for detection of trisomies 13, 18, and 21 were above 98%, as reported by all three companies. Unlike other techniques, WGS-based NIPT can detect other trisomies as well as clinically significant segmental duplications/deletions within a chromosome, which could expand the scope of NIPT. Incorrect results could be due to low fetal fraction, fetoplacental mosaicism, confined placental mosaicism or maternal copy number variation (CNV). Among those, maternal CNV is a significant contributor of false positive results and therefore genome wide scanning plays an important role in preventing the occurrence of false positives. In this article, the bioinformatic techniques and clinical performance of three major companies are comprehensively reviewed.

• Journal of the Korean Society of Visualization
• /
• v.7 no.1
• /
• pp.21-28
• /
• 2009

The study of swirling flow is of technical and scientific interest because it has an internal recirculation field, and its tangential velocity is related to the curvature of streamline. The fluid flow for tubes and elbow of heat exchangers has been studied largely through experiments and numerical methods, but studies about swirling flow have been insufficient. Using the particle image velocimetry(PTV) method, this study found the time averaged velocity distribution with swirl and without swirl along longitude sections and the results appear to be physically reasonable. In addition, streamwise mean velocity distribution was compares with that of other. Furthermore, other experimental investigation was performed to study the characteristics of turbulent water flow in a horizontal circular tube by using liquid crystal. 2D PIV technique is employed for velocity measurement and liquid crystal is used for heat transfer experiments in water. Temperature visualization was made quantitatively by calibrating the colour of the liquid crystal versus temperature using various approaches.

• Education of Primary School Mathematics
• /
• v.8 no.1
• /
• pp.13-22
• /
• 2004

There were a lot of challenges to reform mathematics education. These challenges may include reforms of teaching and learning methods, development of mathematics curriculum and textbooks, innovative resources for teaching mathematics. Although there is considerable consensus that meeting these challenges will require that mathematics teachers have deep insights about mathematics, about students as learners of mathematics, and about teaching method, the teachers themselves may have little knowledge of them. The most of the professional development includes elective participation in reeducation course, workshop, and special lectures which designed to transmit a specific set of ideas, techniques, or materials to teachers. But such approaches treat mathematics teaching as routine and technical, and also provide limited opportunities for meaningful interactions within the teaching community. So, this paper suggests that what is needed to develop professional teachers of mathematics is community where teachers work with colleagues rather than working alone.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.17 no.6
• /
• pp.587-596
• /
• 2015

Recent years have shown great advances in the feasibility of long subsea tunnels. Projects such as the Channel Tunnel, the Stoerebelt Tunnel or the Bosporus Crossing have pushed the boundaries of TBM tunneling technology and fueled the work on feasibility studies for even more challenging projects such as crossing the Qiongzhou or Gibraltar Straits. There are numerous geotechnical challenges such as wide variations of ground conditions, high operation pressures or long tunnel distances and finally geological uncertainties which must be solved in order to attempt such projects. Several operational challenges such as large muck quantities interventions under difficult conditions and long transport distances also have to be tackled. TBM manufacturer and construction industry have developed a number of approaches to these challenges which point into the right technical direction and have been proven successfully in recent experiences. Their further development will allow attempting several megaprojects which are currently under discussion.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.42-51
• /
• 2003

The global demand for underground facilities has increased substantially in the past decades, and a substantial number of underground projects have had to deal with challenging ground conditions in urban environments. Particularly challenging are weak and unstable water bearing soils. Advancements in shielded TBM tech-nology have led to significant improvements regarding the ability to control ground deformations in soft ground. Nonetheless, ground collapse may occur even when the most advanced TBM designs are employed if unexpected adverse ground conditions are encountered or if insufficient stabilizing pressure is transferred to the tunnel face. This paper reviews common approaches for face stability and face pressure transmission calculations, and provides an overview of some of the latest technological developments and considerations for soft ground TBM applica-tions.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.3
• /
• pp.1228-1248
• /
• 2020

Steganalysis & steganography have witnessed immense progress over the past few years by the advancement of deep convolutional neural networks (DCNN). In this paper, we analyzed current research states from the latest image steganography and steganalysis frameworks based on deep learning. Our objective is to provide for future researchers the work being done on deep learning-based image steganography & steganalysis and highlights the strengths and weakness of existing up-to-date techniques. The result of this study opens new approaches for upcoming research and may serve as source of hypothesis for further significant research on deep learning-based image steganography and steganalysis. Finally, technical challenges of current methods and several promising directions on deep learning steganography and steganalysis are suggested to illustrate how these challenges can be transferred into prolific future research avenues.