• Korean Chemical Engineering Research
• /
• v.52 no.2
• /
• pp.154-165
• /
• 2014

Development of unconventional natural resources such as shale gas, shale oil and coal bed methane, has been activated and improved the productivity due to the recent technology advance in horizontal drilling and hydraulic fracturing. However, the flowback water mixed with chemical additives, and the brine water containing oil, gas, high levels of salts and radioactive metals is produced during the gas production. Potential negative environmental impact due to large volumes of the produced wastewater is increasingly seen as the major obstacles to the unconventional natural resource development. In this study an integrated framework for the flowback and brine water treatment is proposed, and we reviewed the upcoming state of the art technology in water treatment. Basic separation processes which include not only membrane, evaporation, crystallization and desalination processes, but the potential water reuse and recycling techniques can be applied for the unconventional natural resource industry.

• Journal of the Korean Institute of Gas
• /
• v.19 no.1
• /
• pp.38-44
• /
• 2015

FDS (Fire Dynamics Simulator) is the most widely used computational fluid dynamics software in the fire safety engineering community, and it is applicable to various evaluations of fire growth and its effects. This study made use of a range of outputs from FDS simulation to predict FED (Fractional Effective Concentration) and FEC (Fractional Effective Concentration) levels which are often adopted to evaluate toxicity of fire smoke. As it is not possible to calculate these values directly from outputs of FDS, it was necessary to produce them by means of additional calculation procedures incorporating results of evacuation simulation. In this study, the latest version of FDS, which was recently updated in November 2013, was utilized for the purpose of quantitative comparison with the old version of FDS. As a result, it was found that they make about 10 percent difference on average in predicting FED and FEC levels for the cable fire case study.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.7
• /
• pp.68-80
• /
• 2002

An approach for composing a performance optimized computational code is suggested for latest microprocessors. The concept of the code optimization, called here as localization, is maximizing the utilization of the second level cache that is common to all the latest computer system, and minimizing the access to system main memory. In this study, the localized optimization of LU-SGS (Lower-Upper Symmetric Gauss-Seidel) code for the solution of fluid dynamic equations was carried out in three different levels and tested for several different microprocessor architectures most widely used in these days. The test results of localized optimization showed a remarkable performance gain up to 7.35 times faster solution, depending on the system, than the baseline algorithm for producing exactly the same solution on the same computer system.

• Journal of the Korean Vacuum Society
• /
• v.19 no.5
• /
• pp.331-340
• /
• 2010

3D fluid based numerical modelling is done for a VHF multi hollow cathode array plasma enhanced chemical vapor deposition system. In order to understand the fundamental characteristics of it, Ar plasma is analyzed with a condition of 40 MHz, 100 Vrf and 1 Torr. For hole array of 6 mm diameter and 20 mm inter-hole distance, plasma is well confined within the hole at an electrode gap of 10 mm. The peak plasma density was $5{\times}10^{11}#/cm^3$ at the center of the hole. When the substrate was assumed at ground potential, electron temperature showed a peak at the vicinity of the grounded walls including the substrate and chamber walls. The reaction rate of metastable based two step ionization was 10 times higher than the direct electron impact ionization at this condition. For $H_2$, the spatial localization of discharge is harder to get than Ar due to various pathways of electron impact reactions other than ionization.

• Journal of Engineering Education Research
• /
• v.4 no.2
• /
• pp.11-19
• /
• 2001

Current educational hydraulic oil systems consist of the composites for the hydraulic circuits. These systems not only could attract students' interests, but also increase the teaching efficiency during the lectures. Thus, the visual hydraulic oil system has been developed to enhance educational efficiency and to improve learning methods. With this new system, the students can easily examine the oil flow for hydraulic oil parts in mechanical engineering experiments. In order to develop the new system, the hydraulic constitute was made of acryl resin, and previous pipes were replaced by transparent and flexible tubes. Red colored oil was also used to visualize the oil flow. Furthermore, if OHP (Over Head Projector) was used for a theoretical lectures, the visual units can be used to classify the differences of the valve structure or the circuits. If lecturers use the developed visual hydraulic system, students can make an effective experiment on the basic theories and principles. Therefore, we can promote the students' interests and materialize the objectives of the subject. The results of this paper can be widely used to improve the efficiency of the mechanical engineering education.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.14 no.1
• /
• pp.32-39
• /
• 2011

When the laws about the security of ships are revised, or voyage conditions are changed, ship owners have converted rather than built new passenger ships including cruise ships recently. As conversion causes a lot of changes in principal dimension, structural strength, hydrodynamic performance, the number of passengers, and cargo capacity, detailed pre-review is needed. But any studies on conversion have not been carried out yet, this study investigated and analyzed the trend of consulting companies' reports (Delta Marine Report, 2005, 2008). As a result, it was found that lengthening conversion brought about the main changes in principal dimension, and performance. Also it was suggested that there be factors for consideration like hull scantling, hull form, and cutting point to minimize side effects when ship owners build ships having lengthening conversion in mind.

• Journal of the Society of Naval Architects of Korea
• /
• v.33 no.4
• /
• pp.60-65
• /
• 1996

Mathematical model of maneuvering motion for a single-screw single-rudder ship established and versatile applications to the special situations of maneuvering are attempted. While, the mathematical model for twin-screw twin-rudder ship is not presented so much, because that type of ship is not popular. Lee et al. have examined the characteristics of such ship by captive model tests in 1988. This paper treats new mathematical models for propeller effective wake ($1-w_p$) and effective neutral rudder angle ${\delta}_R$ in the case of twin-screw twin-rudder ship. And some maneuvering motions are calculated with proposed models and compared with exact simulations.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.15 no.3
• /
• pp.219-230
• /
• 2017

This study was conducted to predict and evaluate the uncertainty of safety after closure of the second phase surface disposal facility of the Gyeongju intermediate and low level repository in Korea. In this study, four scenarios are developed considering both intact and degraded states of multi-layered covers and disposal containers; also, the fluid flow by a rainfall into the disposal facility is simulated. The rainfall conditions are implemented based on the monthly average data of the past 30 years (1985~2014); the simulation period is 300 years, the management period regulated by institutional provisions. As a result of the evaluation of the basic scenario, in which the integrity of both of the containers and the covers is maintained, it was confirmed that penetration of rainfall does not completely saturate the inside of the disposal facility. It is revealed that the multiple cover layers and concrete containers effectively play the role of barrier against the permeation of rainfall.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.1
• /
• pp.3-10
• /
• 1990

Hull form can be described numerically by two approaches, one is to describe a hull form with a set of curves("curve approach"), and the other is to describe it with surfaces directly("surface approach"). This paper describes the numerical definition scheme of hull form using curve approach method which defines the hull form by a set of curves consisting of 2-dimensional transverse section curves and 3-dimensional longitudinal curves. A set of curves in the hull form definition scheme is described by the modified cubic spline which modified the general parametric cubic spline in order to ensure a very smooth curvature distribution within the curve segment even though a curve segment has large tangent angle at its end points. Illustrative examples are given showing the application of the method to represent the hull form of SWATH ship and oceanographic research vessel. Also, examples for hull form transformation are shown by using this method connected with transformation technique.

• Proceedings of KOSOMES biannual meeting
• /
• 2007.05a
• /
• pp.161-168
• /
• 2007

In this paper, the floating body with double barriers is introduced with a study on the flow patterns and characteristics in around the floating body by using 2 frame p article tracking method. This paper introduce an analisys method to predict the characteristics of flow around the neighbording fields of Floating Body with double barriers in order to investigate a high performance model. Flow visualization has conducted in a circulating water channel by a high speed camera and etc. Flow phenomena according to velocity distribution and flow separation around the floating body with double barriers were obtained by two-dimensional PIV system.