• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.35-39
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• 2003

The display technology on the retina is the key role in inspecting the condition of the patients. 2-dimensional retina image is widely used in the eye examination as of today. Recently, 3-dimensional retina image ones have been introduced to this area, but the quality of the image is not fully satisfied to the operator. For the purpose of developing 3-D retina imaging instrument, the optimization of a 3-D retina imaging system using Code-V tool was investigated in this thesis. He-Ne laser having the wavelength 632.8 nm was used to make a power source to detect the retina. Several lenses and mirrors installed on sledge which were developed to perform focus control on 3-D device were designed to make a beam focusing and direct line. Polygon scanner having 24 mirror facets and galvanometer making tilting movement were utilized to make a 2-D laser plane. Also, design of eye ball had been fulfilled to see the focus of the 2-D plane. Reflected ray from retina detected on the sensor array with the same path. All cognitive components were optimized for aberration correction in order to focus on retina. Results of optimization were compared to those of initial designed optics system. On the basis of above results, the result of third aberration has been corrected to stable values to the optical system. MTF evaluating the resolution of an image has been closely correlated to the diffraction limit and PSF indicating the strength distribution of an image has shown the SR value as 0.9998 having high performance. The possibility of new and powerful 3-D retina image instrument was verified by simulating each component of the instrument by Code-V.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.1
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• pp.271-297
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• 2011

Recently, risk of space accident possibility increased in according to commercial space activity and space debris. It failed launch satellite second times in South Korea. Therefore was discussed on liability and insurance issue. Generally, discuss of space insurance be divided two type. Firstly, space insurance relevant to launching satellite and in-orbit. Satellite Launch Insurance and In-Orbit Insurance by the Satellite Operator Secondly, space insurance relevant to Third Party Liability. The former is to protect owner of satellite and operator. The latter is to liable and indemnify owner of satellite and operator's liability. US, UK, France, Russia, South Korea forced to buy space insurance following to domestic law. This is a brief overview of risk allocation and insurance practices in the commercial space transportation industry today. We begin with traditional space transportation, i.e., commercial satellite launches. This is a mature industry with known players. Industry practices have developed and legislation has been adopted in the U.S. and other countries over the past decades to address liability and insurance issues. The primary focus here is on U.S. law, but the discussion of industry practice applies more generally. We then move on to a more exotic form of space transportation: Commercial human space flight. Several private companies are now signing up space tourists for commercial suborbital human space flight, advertised to become available in the near future. The United States amended its launch legislation in 2004 to promote commercial human space flight. But questions remain as to how this new industry will respond to the risk allocation regime established by the U.S. legislation, which leaves both the space flight operator and space tourist exposed to risk and potential liability. As a general proposition, state statutes and contractual waivers alone cannot be relied upon to provide adequate liability protection, and insurance will be required. Federally mandated contractual waivers by space flight participants or liability caps would be helpful to complement insurance solutions. Eventually, as the industry matures, such practices could be extended to an international legal regime. For all the issues mentioned above, I have studied the existing international treaties and several country's domestic law to the space by referring U.S's Commercial Space Launch Amendment Act of 2004 and concluded that uniform legal regime to govern these insurance issues should be established domestically and internationally in the future.

• Journal of KIISE:Software and Applications
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• v.31 no.3
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• pp.293-307
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• 2004

We consider the problem of scheduling tasks of a precedence constrained task graph, where each task has its execution time and deadline, onto a set of identical processors in a way that simultaneously minimizes the number of processors required and the total tardiness of tasks. Most existing approaches tend to focus on the minimization of the total tardiness of tasks. In another methods, solutions to this problem are usually computed by combining the two objectives into a simple criterion to be optimized. In this paper, the minimization is carried out using a multiobjective genetic algorithm (GA) that independently considers both criteria by using a vector-valued cost function. We present various GA components that are well suited to the problem of task scheduling, such as a non-trivial encoding strategy. a domination-based selection operator, and a heuristic crossover operator We also provide three local improvement heuristics that facilitate the fast convergence of GA's. The experimental results showed that when compared to five methods used previously, such as list-scheduling algorithms and a specific genetic algorithm, the Performance of our algorithm was comparable or better for 178 out of 180 randomly generated task graphs.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1229-1244
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• 2017

In recent years, as demand for data-based analytical methodologies increases in various fields, optimization methods have been developed to handle them. In particular, various constraints required for problems in statistics and machine learning can be solved by convex optimization. Alternating direction method of multipliers (ADMM) can effectively deal with linear constraints, and it can be effectively used as a parallel optimization algorithm. ADMM is an approximation algorithm that solves complex original problems by dividing and combining the partial problems that are easier to optimize than original problems. It is useful for optimizing non-smooth or composite objective functions. It is widely used in statistical and machine learning because it can systematically construct algorithms based on dual theory and proximal operator. In this paper, we will examine applications of ADMM algorithm in various fields related to statistics, and focus on two major points: (1) splitting strategy of objective function, and (2) role of the proximal operator in explaining the Lagrangian method and its dual problem. In this case, we introduce methodologies that utilize regularization. Simulation results are presented to demonstrate effectiveness of the lasso.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.35-47
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• 2005

This paper is to review a literature concerning Bus Transit Route Network Design(BTRNDP), to describe a future study direction for a systematic application for the BTRNDP. Since a bus transit uses a fixed route, schedule, stop, therefore an approach methodology is different from that of auto network design problem. An approach methodology for BTRNDP is classified by 8 categories: manual & guideline, market analysis, system analytic model. heuristic model. hybrid model. experienced-based model. simulation-based model. mathematical optimization model. In most previous BTRNDP, objective function is to minimize user and operator costs, and constraints on the total operator cost, fleet size and service frequency are common to several previous approach. Transit trip assignment mostly use multi-path trip assignment. Since the search for optimal solution from a large search space of BTRNDP made up by all possible solutions, the mixed combinatorial problem are usually NP-hard. Therefore, previous researches for the BTRNDP use a sequential design process, which is composed of several design steps as follows: the generation of a candidate route set, the route analysis and evaluation process, the selection process of a optimal route set Future study will focus on a development of detailed OD trip table based on bus stop, systematic transit route network evaluation model. updated transit trip assignment technique and advanced solution search algorithm for BTRNDP.

• The Mathematical Education
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• v.61 no.2
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• pp.287-303
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• 2022

The purpose of this study is to draw implications for the improvement in the CSAT by analyzing structures and tasks in the Abitur. To this end, it analyzes the mathematics test system with a focus on the basic and advanced level examination systems, the operator, the using technology, and mathematical formulas. And the characteristics of tasks in the 2021 Abitur were analyzed. As a result of the analysis, first, Germany evaluates whether students have the competency emphasized in the curriculum at Abitur. Second, Germany, which emphasizes the proper use of technology, utilizes both tasks that use technology and those that do not in the Abitur. Third, the Abitur consists of most of the tasks using promised operators and uses various types of operators to present various types of questions to evaluate competence. Fourth, the Abitur includes not only simple structured items consisting of 2-3 subtasks but also tasks dealing in depth with a single situation centered on a big idea. Finally, mathematical justification and proof play an important role in the Abitur. Based on this, some specific measures for improving the CSAT were suggested.

• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.837-848
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• 2005

A multi-scale database is a set of spatial database, covering same geographic area with different scales and it can be derived from pre-existing databases. In the derivation processes of a new multi-scale spatial database, the geometries and topological relations on the source database can be transformed and the transformation can be the cause of the lack of integrity Therefore, it is necessary to assess the transformation whether it is consistent or not after the derivation process of a new multi-scale database. Thus, we propose assessment methods for the topological consistency between a source database and a derived multi-scale database in this paper. In particular, we focus on the case that 2-dimensional objects are collapsed to 1-dimensional ones in the derivation process of a multi-scale database. We also describe implementation of the assessment methods and show the results of the implementation with experimental data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.481-489
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• 2017

Situation awareness means recognizing everything necessary to understand progress in a flight or aircraft maintenance work. Situation awareness is based on more than simply recognizing important about the environment, and it is important to provide the meaning of information in an integrated form. The KHP provides the pilot with integrated situation display for an integrated form of situation awareness and warning that synchronizes the priority based audible signal with the visual signal. Provide integrated display and warning to reduce operator error and enable operators to focus on mission critical tasks and events. This paper introduces the integrated situation display and warning design implemented in the KHP.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1025-1030
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• 2019

This paper describes SON(: Self Organization Network) technology in LTE networks. The SON is a unique feature of LTE compared to previous cellular systems such as UMTS and GSM, and it is a tool that effectively derives the best performance in the time-varying wireless radio environment. Also, the SON has the ability for the operator to automate the setting of the network, allowing for centralized planning and reducing the need for manual work. The SON is largely divided into three categories: Self-Configuration, Self-Optimization, and Self-Healing. Each large categories has a detailed description of technology, and the technologies in each categories are gathered to complete the technology called the SON. In this paper, we focus on MRO which is one of the Self-Optimization technique in each of the three categories.

• Journal of Korean Neurosurgical Society
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• v.40 no.1
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• pp.16-21
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• 2006

Objective : Young neurosurgeons need to focus on the mortality and morbidity of aneurysmal neck clipping to develop a personal experience with an initial series. Methods : Total 88 aneurysms from 75 patients who underwent neck clipping by the same operator from 2001 to 2004 were reviewed. Patients were divided into three groups : first year [Group I], second year [Group II], and third year [Group III] in each group. Location of aneurysm, age, Fisher grade, Hunter-Hess grade [H-H grade], postoperative Glasgow outcome scale [GOS], and complications related to surgical procedures were evaluated with Chi-square and logistic regression analyses. Results : Fourteen patients had complications related to surgery [18.7%]. The major causes of mortality and morbidity related to surgery were cerebral infarction, hemorrhage and brain swelling due to intraoperative rupture, brain retraction and vasospasm. Among the 4 cases of mortality were 2 patients in Group I, 1 patient in Group II and 1 patient in Group III, and location of aneurysms were 2 internal carotid artery[ICA] and 2 posterior communicating artery[PCoA] aneurysms. There were 4 morbidity and new neurological deficits in Group I, 4 in Group II and 2 in Group III. Although mortality and morbidity during the learning curve had a statistical significance in H-H grade, age [>60 years old], and aneurysm location [especially ICA aneurysm] as variables, mortality mainly occurred in ICA and PCoA aneurysms. Conclusion : Experienced supervision or endovascular approach should be considered for the treatment of ICA and PCoA aneurysms during the learning curve.