• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.8-22
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• 2015

Most jet spray and atomization simulations are done with the Eulerian method which has inherent disadvantage in representing jet breakups and droplets. Full Lagrangian particles method called Smoothed Particle Hydrodynamics(SPH) is used in this work. We develop the SPH code and perform validations that confirm the suitability of our SPH method for simulating liquid jet atomization problem. Then, we conduct the simulation of liquid-liquid swirl coaxial injector for comparison against the experimental data.

• The Korean Journal of Air & Space Law and Policy
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• v.29 no.2
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• pp.205-237
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• 2014

Last 50 years there were a lot of space subjects launched by space activities of many states and these activities also had created tremendous, significant space debris contaminating the environment of outer space. The large number of space debris which are surrounding the earth have the serious possibilities of destroying a satellite or causing huge threat to the space vehicles. For example, Chinese anti-satellite missile test was conducted by China on January 11, 2007. As a consequence a Chinese weather satellite was destroyed by a kinetic kill vehicle traveling with a speed of 8 km/s in the opposite direction. Anti-satellite missile tests like this,contribute to the formation of enormous orbital space debris which can remain in orbit for many years and could interfere with future space activity (Kessler Syndrome). The test is the largest recorded creation of space debris in history with at least 2,317 pieces of trackable size (golf ball size and larger) and an estimated 150,000 debris particles and more. Several nations responded negatively to the test and highlighted the serious consequences of engaging in the militarization of space. The timing and occasion aroused the suspicion of its demonstration of anti-satellite (ASAT) capabilities following the Chinese test of an ASAT system in 2007 destroying a satellite but creating significant space debris. Therefore this breakup seemed to serve as a momentum of the UN Space Debris Mitigation Guidelines and the background of the EU initiatives for the International Code of Conduct for Outer Space Activities. The UN Space Debris Mitigation Guidelines thus adopted contain many technical elements that all the States involved in the outer space activities are expected to observe to produce least space debris from the moment of design of their launchers and satellites until the end of satellite life. Although the norms are on the voluntary basis which is normal in the current international space law environment where any attempt to formulate binding international rules has to face opposition and sometimes unnecessary screening from many corners of numerous countries. Nevertheless, because of common concerns of space-faring countries, the Guidelines could be adopted smoothly and are believed faithfully followed by most countries. It is a rare success story of international cooperation in the area of outer space. The EU has proposed an International Code of Conduct for Outer Space Activities as a transparency and confidence-building measure. It is designed to enhance the safety, security and sustainability of activities in outer space. The purpose of the Code to reduce the space debris, to allow exchange of the information on the space activities, and to protect the space objects through safety and security. Of the space issues, the space debris reduction and the space traffic management require some urgent attention. But the current legal instruments of the outer space do not have any binding rules to be applied thereto despite the incresing activities on the outer space. We need to start somewhere sometime soon before it's too late with the chaotic situation. In this article, with a view point of this problem, focused on the the Chinese test of an ASAT system in 2007 destroying a satellite but creating significant space debris and tried to analyse the issues of space debris reduction.

• Journal of Korean Library and Information Science Society
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• v.24
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• pp.485-517
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• 1996

The purpose of this study is to investigate typical ethical problems found in the technical and public services areas. The followings are the summary of the study. There are three distinct elements that govern ethical problems. One element is legal laws. The copyright law and the privacy act are exact examples. The copyright law has strong influence on the inter library loan service where the majority requests from the users are reproduction of copies. The privacy act also creates difficulties for librarians. Most requests for circulation records infringe on the privacy of library user. And advance online access systems also violates the privacy of library users. The second element is the code or rules that private organization has created. American Library Association created many statements that regulate the conduct of librarians. The bill of right, the professional code of ethics and policy on the confidentiality of library records have strong implications in the obligation of librarian. In the case of censorship at the selection of library materials, the code is a defensive tool against intellectual freedom. Yet self-censoring are prevailing practice among librarians. The thirds element is the competence of librarians. The analyzed table 3 showed that beside two elements, the rest of matters are competence required by librarians. The one aspect of it is humaneness and the other one is technical aspects. Technical aspect of competence are:(l) managerial and operational ability (2) communication skill (3) leadership (4) structure of knowledge and (5) self developing professionalism. Humanity aspect of competence are:(l) trust(fiduciary relationship) gained by diligence, objective judgement, ability, belief, rationality, integrity, kindness) (2) objectiveness (free from bias) (3) user-oriented consideration (need, interest, equal treatment, information gap) (4) caution in providing information (5) pride and (6) ability to distinguish advice and guidance specially in medical and law library.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.2
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• pp.437-447
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• 2018

Virtual Reality (VR) is becoming a new standard in the game industry. PokeMon GO is a representative example of VR technology. The day after the launch of PokeMon Go in the U.S, It has achieved the highest number of iOS App Store downloads. This is an example of the power of VR. VR comprises gyroscopes, acceleration, tactile sensors, and so on. This allow users could be immersed in the game. As new technologies emerge, new and different threats are created. So we need to research the security of VR technology and game system. In this paper, we conduct a threat analysis for information assurance of VR device (Oculus Rift) and game system (Quake). We systematically analyze the threats (STRIDE, attack library, and attack tree). We propose security measures through DREAD. In addition, we use Visual Code Grepper (VCG) tool to find out logic errors and vulnerable functions in source code, and propose a method to solve them.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.398-404
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• 2013

The simulation of the ballistic trajectory of penetrator into the spaced multi-layer RC targets is very important to predict the hitting condition in subsequent target. Because of perturbation by lateral load of penetrator caused by asymmetric hitting position between penetrator and steel bar reinforcement, penetrator rotates and deviates from the straight path. Therefore, penetration capability of penetrator is decreased in the subsequent targets. This paper presents the result of the penetration of steel-bar-reinforced concrete target by using the explicit finite element code LS-DYNA. A series of computations is performed and compared to experimental data and the computed results are in good agreement with the experimental results over a wide range of velocities. And then we conduct the simulation according to various RC target hitting condition and impact velocities.

• Journal of architectural history
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• v.19 no.4
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• pp.109-123
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• 2010

The main functions of a Buddhist temples are as a place for Buddhist services and a place for sermons and each ancient Buddhist temple was equipped with a main and separate building. After Zen Buddhism was first introduced, there was a tendency to change the terms to Buddhist sanctuary and altar, as set forth in the Zen Buddhism code of conduct called 'Cheonggyu(淸規)'. As such, it was thought that the division between Buddhist service space and preaching space were relatively firm until the Goryeo Dynasty. However in the period from the end of the Goryeo to the beginning of the Joseon Dynasty there was an increasing tendency of integration of the two buildings. It can be seen that, in cases where both buildings remained, statues of Buddha were enshrined in these buildings without any distinction. Eventually it is led to the tradition of duo-Buddhist sanctums.

• Coupled systems mechanics
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• v.10 no.6
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• pp.491-507
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• 2021

The aim of this paper is to conduct a hydrodynamic analysis of fluid flow over different weir types using the analytical solution, the physical model taken from another article, and numericalsimulations through the Smoothed particle hydrodynamic method (SPH) using the compiled DualSPHysics source code. The paper covers the field of real fluid dynamics that includes a description of different proposed types of weirs in various flow regimes and the optimal solution for the most efficiency structure shape. A detailed presentation of the method, the structure and it's characteristics are included. Apart from the single stepped weir, two other weir types are proposed: a Divided type and a Downstream slopped type. All of them are modeled using the SPH method.

• Journal of Information Technology Services
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• v.6 no.3
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• pp.141-162
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• 2007

In this study, we conduct a case analysis on EZmedicom which is one of the leading companies in e-Marketplace for medical fields. By examining major business models of EZmedicom, we provide the success factors in launching the electronic commerce to the potential companies which are interested in participating in e-marketplace for medical fields. Especially, we deduct the solution, logistics field, and electronic group-purchasing as its major business model. Based on these factors, we also propose the MDvan solution which is one of the electronic purchase and supply system, Ezlogis that is the system supporting logistics parts in medical fields, VMI(vendor management inventory), standardization of item code and the linkage of SCM as its critical success factors of EZmedicom. The findings of this study suggest practical and managerial implications for e-Marketplace implementation in the medical field and further research.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.6
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• pp.625-630
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• 2014

Asynchronous digital circuits working in military and space environments are often subject to the adverse effects of radiation faults. In this paper, we propose a new hardening technique against radiation faults. The considered digital system has the structure of DMR (Double Modular Redundancy), in which two sub-systems conduct the same work simultaneously. Based on the output feedback, the proposed scheme diagnoses occurrences of radiation faults and realizes immediate recovery to the normal behavior by overriding parts of memory bits of the faulty sub-system. As a case study, the proposed control scheme is applied to an asynchronous dual ring counter implemented in VHDL code.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.695-702
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• 2001

In this paper, the drop/impact simulation for a mobile phone has been carried out with the explicit code LS-DYNA and its validation has been experimentally verified. The small size of this kind of electronics products makes it time-consuming, and difficult to conduct drop tests to detect the failure mechanism and identify their drop behaviors. Strict drop/impact performance criteria of such hand held electronic products as mobile phones play an important role in their design because these products must withstand both normal and unexpected shock. Usually, the product durability on drop impact depends on designers experience. The present reliable methodology of drop/impact simulation provides an efficient and powerful vehicle to improve the design quality and reduce the design period.