• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.527-530
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• 1997

An automated process planning system for cold forging of non-axisymmetric parts of comparatively simple shape was developed in this study. Programs for the system have been written with Visual LISP in the AutoCAD using a personal computer and are composed of four main modules such as input module, shape cognition and shape expression module, material diameter determination module and process planning module. The design rules and knowledges for th system are extracted from the plasticity theories. handbook, relevant reference and empirical knowledge of field experts. Generally, in forging, only front view is needed for expression of axisymmetric parts, but non-axisymmetric parts are needed both front view and plane. At the plane, this system cognizes the external shape of non-axisymmetric parts - number of sides of regular polygon and radius of a circle circumscribing the polygon of n sides. At the front view, the system perceives diameter of axisymmetric portions and hight of primitive geometries such as polygon, cylinder, cone, concave, convex, etc.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.591-603
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• 1999

A computer-aided process planning system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has been reported yet. Therefore, this study investigates process sequence design in deep drawing process and constructs a computer-aided process planning system for non-axisymmetric motor frame products with elliptical shape. The system developed consists of three modules. The first one os a 3-dimensional modeling module to calculate surface area for non-axisymmetric products. The second one is a blank design module that creates an oval-shaped blank with the identical surface area. The third one is a process planning module based on production rules that play the best important roles in an expert system for manufacturing. The production rules are generated and upgraded by interviewing with field engineers. Especially, drawing coefficient, punch and die radii are considered as main design parameters. The constructed system for elliptical deep drawing products would be very useful to reduce lead time and improve accuracy for production.

• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.20-25
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• 2020

To design a wide-field two-mirror system, the system must feature an off-axial field, to avoid ray obstruction and field screening by the secondary mirror. The off-axial aberrations of the system cannot be corrected sufficiently, though, because there are only a few design parameters. The present study designs an improved off-axial-field two-mirror system using a decentered aperture stop.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.55.4-55.4
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• 2021

한국천문연구원에서는 낮은 표면밝기(Low Surface Brightness; LSB)의 천체를 효율적으로 관측할 수 있는 소형(〉30cm) 광시야(〉1°×1°) 광학망원경 및 관측기술 개발을 통한 은하형성 규명 연구를 수행 중에 있다. 이번에 개발한 K-DRIFT pathfinder는 비축 자유곡면 3반사 망원경 시스템(Linear Astigmatism Free-Three Mirror System; LAF-TMS)으로 넓은 시야에서 고품질의 이미지를 효율적으로 얻을 수 있는 광학 설계를 적용하고, 배경 값 변동 요인을 분석하여 가까운 우주의 LSB 천체 관측에 최적화될 수 있도록 하였다. 이번 특별세션에서는 '왜 LSB 우주 탐사를 하고, K-DRIFT를 개발하는지?'에 대해서 소개하고, K-DRIFT pathfinder의 개발 과정, 보현산 천문대에서의 시험관측 결과 소개와 함께, LSB 천체 연구를 위한 맞춤형 시뮬레이션 개발 및 수행 내용을 소개한다.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.4
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• pp.240-247
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• 2023

In this study, morphological and hydrodynamic characteristics of the non-axisymmetric supercavity generated behind a disk-shaped cavitator were examined. By extending the previous study on axisymmetric supercavitating flow based on a boundary element method, hydrodynamic forces acting under the angle of attack condition of 0 to 30 ° and shape characteristics of the supercavity were analyzed. The results revealed that increasing the angle of attack by 30 ° reduced the length and width of the cavity by about 15% and the volume by about 40 %. An empirical formula that can quantitatively estimate the geometrical characteristics and change of the cavity was derived. It is expected that this method can be used to evaluate the shape information and force characteristics of the supercavity for the control of the vehicle in a very short time compared to the viscous analysis in the initial design stage of the supercavity underwater vehicle.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.289-298
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• 2006

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the portability of mobile clients. Mobile computing satisfies user's demands for convenience and performance to use information at any time and in any place, but it has many problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Continuous Query Processing System(MCQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client server environments. We proved the superiority of the proposed MCQPS by comparing its performance to the C I S(Client-Intercept-Slaver) model. In Addition, we experiment on proposed index structure and methodology in various methods.

• The KIPS Transactions:PartD
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• v.12D no.4 s.100
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• pp.521-530
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• 2005

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the Portability of mobile clients. Mobile computing satisfies user's demands for convenience and Performance to use information at any time and in any Place, but it has many Problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Query Processing System(MQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client-server environments. In addition, we proved the superiority of the proposed MQPS by comparing its performance to the C-I-S(Client-Intercept- Server) model.

• Transactions of Materials Processing
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• v.11 no.5
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• pp.405-413
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• 2002

A process planning system for cold forging of non-axisymmetric parts of comparatively simple shape was developed in this study. Programs for the system have been written with Visual LISP in AutoCAD. Shape of the product must be drawn with the solid line and the hidden line, and with the plane and front view, as well. At the plane, the system recognizes the external shape of non-axisymmetric portions - the number of the sides of the regular polygons and the radii of circles inscribing and circumscribing the polygon. At the front view, the system cognizes the diameter of axisymmetric portions and the height of the primitive geometries such as polygon, cylinder, cone, concave, convex, etc. The system perceives that the list developed from the solid line must be formed by the operation of forward extrusion or upsetting, and that the list developed from the hidden line must be formed by the operation of backward extrusion. The system designs the intermediate geometries again by considering clearance between workpiece and die, and then finally the billet diameter, in reverse order from the finished product, on the basis of volume constancy and using the operations, the forming sequence, the number of operations and the intermediate geometries which were already designed. The design rules and knowledges for the system were extracted from the plasticity theories, handbook, relevant reference and empirical knowledge of field experts. Suitability of the process planning was analyzed using SuperForge of FVM simulation package. The results of analysis showed good formability.

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.2
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• pp.53-62
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• 1974

본고(本考)는 포항종합제철(浦項綜合製鐵) 전용항(專用港)의 확장계획(擴張計劃)에 따라서 원료(原料) 운반선(運搬船)의 적정(適正) 크기 및 속도(速度)를 결정(決定)하기 위한 타당성(妥當性) 조사(調査) 연구(硏究)의 예비작업(豫備作業)이다. 먼저 그 기준(基準)으로 소요운임율(所要運賃率)을 택(擇)하여 선박(船舶)의 크기, 속도(速度) 및 상대방(相對方) 원료적출항(原料積出港)에 따라서 수송비(輸送費)를 계산(計算)한 후에 그 결론(決論)으로 선박(船舶)의 대형화(大型化)의 필요성(必要性)을 보였으며, 이 계산결과(計算結果)를 토대(土臺)로 선박(船舶)의 대형화(大型化) 및 효과(效果)를 시설확장(施設擴張)에 투자(投資)되는 자금(資金)을 연차적(年次的)으로 비교(比較)하여 현재(現在) 추진중(推進中)에 있는 포항종합제철(浦項綜合製鐵) 전용항(專用港) 확장계획(擴張計劃)를 검토(檢討)함으로써 선박(船舶)의 적정(適正)크기가 DWT 약(約) 10만(萬) ton임을 보여준다. 또한 제2종합제철(第2綜合製鐵)과의 관계(關係)도 고려(考慮)하여 원료비축기지(原料備蓄基地)와 같은 새로운 시스템에 대한 종합적(綜合的)이고 세밀(細密)한 검토(檢討)의 필요성(必要性)을 보인다.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.149-162
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• 2010

The most serious problem in oil stockpiles with artificial underground cavern is maintaining the stability of ground water system. In order to understand the ground water system around K-1 site, we determined the regional flow direction and level distribution of groundwater, and investigated the major geologic factors influencing their flow system. Reactivated surface along the contact between granite and gneiss, and fractures and faults along the long acidic dyke may contribute as important pathways for groundwater flow. Within K-1 site, groundwater level fluctuation is closely related to the rainfall events and injection from surface or influx water. In this project, the effect of groundwater pumping from the southern wells was examined. Based on equations relating water level drawdown to pumping rate at those wells, their pumped outflow of groundwater ranged from $80\;m^3$/day to less than $250\;m^3$/day. The modeling results with MODFLOW imply that the previous groundwater pumping at distance of 1.2 km may not affect the groundwater level variations of the K-1 site. However, continuous pumping work at quantity over $250\;m^3$/day in this area will be able to affect the groundwater system of the K-1 site, particularly along the acidic dyke.