• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.03a
• /
• pp.203-208
• /
• 1998

Materials of the Frame hole in fishing trackle reel is made up a number large and small holes. Thus, it is difficult to effective machining. Abrasive flow machining(AFM) is useful to polish a internal or external surface of the 3-dimensional shape parts, which are used in many fields such as aerospace, automative, semi-conductor, and medical component industries. The machining process is that two hydraulic cylinders, which are located face to face, enforce abrasive media to the passage between workpiece and tooling parts alternately, and then the abrasives include in the media pass the passage and polish the surface of workpiece. The media which is made of polymer and abrasives plays the role of the tool for deburring or polishing complex shap workpiece by its viscoelastic characteristics. In this study, the abrasive media for abrasive flow machining was made by mixing viscielastic polymer with alunina and silicon carbide abrasive. Also, we present AFM device design and preliminary results of an investigation in to some aspects of the AFM process performance in fishing trackle reel.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.939-944
• /
• 2003

The analysis involves an adaptive grid that is created under a criterion of element categorization of filling states and locations in the total region at each time step. By using an adaptive grid wherein the elements, finer than those in internal and external regions, are distributed at the surface region through refinement and coarsening procedures, a more efficient analysis of transient fluid flow with free surface is achieved. Using the proposed numerical technique, the collapse of a dam is analyzed. The numerical results agree well with the theoretical solutions as well as with the experimental results. Through comparisons with the numerical results of several cases using different types of grids, the efficiency of the proposed technique is verified.

• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.1090-1092
• /
• 1999

In this paper, multi discharge type ozonizer has been designed and manufactured. The of ozonizer is equipped with three electrodes(central electrode of screw shape, internal electrode and external electrode). This paper describes the following two characteristics: (1) The characteristics of discharge with variation of output voltage of AC H.V source, flow rate of oxygen supplied gas and discharge voltage. (2) The characteristics of ozone generation by varying flow rate and discharge power.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.11a
• /
• pp.253-256
• /
• 2000

In order to commercialize the low cost composite fabrication technology in the area of domestic aerospace structure field, Resin Transfer Molding process has been considered as an alternative process to replace the high cost autoclave technology. The end part for the development of RTM process is the control rod of flight control system of aircraft. A braided preform was triaxially designed to improve the dimensional stability and mechanical property in the direction of external loads. Through the flow analysis using CVFEM, the resin filling time was calculated and the resin injection method was determined. The results of the flow analysis were directly applied to RTM mold design. The control rod was successfully manufactured by RTM process using internal pressure. The length and outer diameter of the manufactured part are 1148mm and 32mm, respectively.

• Korean Journal of Bronchoesophagology
• /
• v.3 no.1
• /
• pp.159-163
• /
• 1997

The complications of deep neck infection have become much less common in the antibiotic era. The vascular complications of deep neck infection can have devasting consequences. Most commonly, the internal carotid artery is involved, although the common carotid and external carotid artery can also be affected.0 the cases of patients with a protracted course, recurrent bleeding, cranial neuropathies, or trismus, the presence of vascular complications must be considered. Appropriate imaging should be carried out to allow the localization of the infection and ascertain the status of the vessels in the neck The vascular structures can be imaged with duplex doppler or color doppler flow ultrasound to see the flow between the mass and vessels. Also angiography plays a key role in the diagnosis and management of vascular complication of deep neck infection. Prompt diagnosis and treatment of these patients is necessary to prevent significant hemmorrhagic complications. We experienced a case of pseudoaneurysm of the common carotid artery secondary to deep neck infection treated successfully with surgical excision in 45-year-old-male.

• Prospectives of Industrial Chemistry
• /
• v.24 no.3
• /
• pp.28-41
• /
• 2021

고분자 시스템의 경우 매우 상이한 시간 및 길이 스케일(time and length scale)에 연관된 복잡한 내부 구조(internal structure)를 가지고 있기 때문에 전통적인 실험 방법만으로는 체계적이고 종합적인 연구가 쉽지 않다. 최근 다양한 시간 및 길이 스케일에 연관된 연구를 진행할 수 있는 다중 스케일 전산 모사(multiscale computer simulation) 방법은 이러한 고분자 시스템 연구에 있어서 새로운 대안으로 각광받고 있다. 본 논문에서는 최근 급격한 발전을 이룬 고분자 용액(polymeric liquid) 시스템에 대한 평형(equilibrium) 및 비평형(nonequilibrium) 전산 모사(computer simulation) 방법들에 관해 소개하고 이를 통합적으로 해석할 수 있는 다중 스케일 전산 모사 방법에 대해 여러 가지 사례를 들어 살펴보았다.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.23 no.3
• /
• pp.8-17
• /
• 2015

In this research, low fidelity air/heat load analysis was conducted for the intake of high speed vehicle. For air/heat load calculations, aerodynamic properties at the surface and the boundary layer edge were estimated using Taylor-Maccoll equation for conical flow, shockwave relation and Prandtl-Meyer expansion equation for internal and external flow. Couette flow assumption and Reynolds analogy were used in order to calculate convective heat transfer coefficient. In order to calculate skin friction coefficient for heat transfer coefficient analysis, Van Driest method II and Reference Enthalpy method were considered. An axis symmetric SCRAMJET model was selected as a reference configuration for verifying the proper implementation of the present method. Comparison of the results using the present method and Computational Fluid Dynamic analysis showed that the present method is valuable for efficiently providing pressure and heat loads for air-intake structure design of the high speed air vehicle.

• Korean Journal of Health Education and Promotion
• /
• v.29 no.4
• /
• pp.83-99
• /
• 2012

Objectives: The purpose of this review is to introduce reporting guidelines for health promotion research in an effort to enhance systematic structure and quality of health promotion research reported in academic papers. Methods: Widely accepted guidelines were selected for description, which focus on 4 distinct types of research design. Checklists and flow diagrams are described and compared. Results: CONSORT Statement is reporting guidelines for randomized controlled trials with a 25-item checklist and a flow diagram. TREND Statement with a 22-item checklist is to guide reporting of health research in nonrandomized design. STROBE Statement is a compiled guidelines for observational health research, accompanied by a 22-item checklist in a combined edition. PRISMA Statement consists of a 27-item checklist and a flow diagram, providing guidelines for reporting systematic reviews and meta-analyses. All items on the checklists and flow diagrams were introduced and discussed. Conclusion: Solid understanding of research designs and adoption of reporting guidelines will enhance the quality of research with information on internal and external validity. Education and training of researchers on the research reporting is required along with systems level adoption of efforts for research enhancement.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.40 no.1
• /
• pp.50-56
• /
• 2017

The IRR (internal rate of return) is often used by investors for the evaluation of engineering projects. Unfortunately, it is widely known that it has serial flaws. Also, External rate of returns (ERRs) such as ARR (Average Rate of Return) or MIRR (MIRR, Modified Internal Rate of Return) do not differentiate between the real investment and the expenditure. The PRR (Productive rate of return) is faithful to the conception of the return on investment. The PRR uses the effective investment instead of the initial investment. In this paper, we examined two cases of the engineering project. the one is a traditional engineering project with financing activity, another is the project with R&D. Although the IRR has only one value, it overestimates or underestimate profitabilities of Engineering Projects. The ARR and the MARR assume that a returned cash reinvest other projects or assets instead of the project currently executing. Thus they are only one value of a project's profitability, unlike the IRR. But the ARR does not classify into the effective investment and non-investment expenditure. It only accepts an initial expenditure as for an investment. The MIRR also fails to classify into the investment and the expenditure. It has an error of making a loss down as the investment. The IRR works as efficiently as a NPW (Net Present Worth). It clearly expresses a rate of return in respect of an investment in an engineering project with a loan. And it shows its ability in an engineering project with a R&D investment.

• Transactions of the Korean hydrogen and new energy society
• /
• v.33 no.5
• /
• pp.557-565
• /
• 2022

The effect of flow configuration in ammonia-fed solid oxide fuel cell are investigated by using a three-dimensional numerical model. Typical flow configurations including co-flow and counter-flow are considered. The ammonia is directly fed into the stack without any external reforming process, resulting in an internal decomposition of NH3 in the anode electrode of the stack. The result showed that temperature profile in the case of counter-flow is more uniform than the co-flow configuration. The counter-flow cell, the temperature is highest at the middle of the channel while in the case of co-flow, the temperature is continuously increased and reached maximum value at the outlet area. This leads to a higher averaged current density in counter-flow compared to that of co-flow, about 5%.