• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.255-261
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• 2003

Tunnelling in poor and heterogeneous ground is a difficult task. Even with a good geological investigation, uncertainties with respect to the local rock mass structure will remain. Especially for such conditions, a reliable short-term prediction of the conditions ahead and outside the tunnel profile are of paramount importance for the choice of appropriate excavation and support methods. The information contained in the absolute displacement monitoring data allows a comprehensive evaluation of the displacements and the determination of the behaviour and influence of an anisotropic rock mass. Case histories and with numerical simulations show, that changes in the displacement vector orientation can indicate changing rock mass conditions ahead of the tunnel face (Schubert & Budil 1995, Steindorfer & Schubert 1997). Further research has been conducted to quantify the influence of weak zones on stresses and displacements (Grossauer 2001). Sellner (2000) developed software, which allows predicting displacements (GeoFit$\circledR$). The function parameters describe the time and advance dependent deformation of a tunnel. Routinely applying this method at each measuring section allows determining trends of those parameters. It shows, that the trends of parameter sets indicate changes in the stiffness of the rock mass outside the tunnel in a similar way, as the displacement vector orientation does. Three-dimensional Finite Element simulations of different weakness zone properties, thicknesses, and orientations relative to the tunnel axis were carried out and the function parameters evaluated from the results. The results are compared to monitoring results from alpine tunnels in heterogeneous rock. The good qualitative correlation between trends observed on site and numerical results gives hope that by a routine determination of the function parameters during excavation the prediction of rock mass conditions ahead of the tunnel face can be improved. Implementing the rules developed from experience and simulations into the monitoring data evaluation program allows to automatically issuing information on the expected rock mass quality ahead of the tunnel.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1154-1158
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• 1995

Electrical Discharge Machining, with its ability to machine hard metals and tough shapes has become a very desirable process. In the past few years, Electrical Discharge Machining (EDM) has been solidly established in tool-room and large-scale production. However, in spite of its indispensability in many areas of metal removal applications, the theoretical basis of EDM process is yet to be established. More importantly, the information regarding essential technology parameters such as machining rate and resulting surface roughness integrity, has not been raised to the level of a general technical science. The paper presents a method, which can be determining approprate machining parameters for the given parameters such as electrode wear and surface roughness based on machining guideline utilizing neural networks.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.176-179
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• 1998

In general, machining time by electrical discharge machining (EDM) process is much longer than that of cutting process, so rough-cut has done for the purpose of reducing machining time prior to EDM Nowadays EDM speed is improving due to the advance of EDM capacity. Therefore a new method, machining a raw material directly by EDM without rough-cut, is used widely. EDM area is varies according to the EDM position in three-dimensional EDM process, so EDM parameters should be determined adaptively based on the EDM area to increase productivity. However it is difficult to calculate EDM area corresponding to the EDM position the EDM workers who have experience in shop floor determine machining parameters by experience. This paper proposes a method for determining EDM parameters based on EDM area corresponding to EDM position.

• 한국진공학회지
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• 제9권4호
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• pp.419-427
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• 2000

본 연구는 원자의 주변 환경에 따른 각각의 확산 속도를 구할 수 있는 기구를 제시하였다. STM 또는 HRLEED 등의 실험과 kinetic Monte Carlo(KMC) 시뮬레이션 계산과의 비교를 통하여 테라스 위 흡착 원자의 확산장벽, step 끝 부착 원자의 탈착 확산 장벽, 잘 알려진 Schwoebel 장벽을 포함한 각각의 확산 장벽을 구할 수 있었다. 팔-넓이, 군집 밀도, 거칠기 등이 시뮬레이션 계산과 실험 결과를 비교하는 데에 가장 적절한 원자단위의 구조변수들임을 확인하였고, 특히 아직 잘 사용되지 않은 구조 계수인 가지폭이 확산 장벽을 구별하여 구하는 데에 중요한 역할을 하는 것을 확인하였다.

• 수산해양기술연구
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• 제49권1호
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• pp.18-28
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• 2013

It was compared the estimated parameters by the surplus production from three different models, i.e., three types (Schaefer, Gulland, and Schnute) of the traditional surplus production models, a stock production model incorporating covariates (ASPIC) model and a maximum entropy (ME) model. We also evaluated the performance of models in the estimation of their parameters. The maximum sustainable yield (MSY) of small yellow croaker (Pseudosciaena polyactis) in Korean waters ranged from 35,061 metric tons (mt) by Gulland model to 44,844mt by ME model, and fishing effort at MSY ($f_{MSY}$) ranged from 262,188hauls by Schnute model to 355,200hauls by ME model. The lowest root mean square error (RMSE) for small yellow croaker was obtained from the Gulland surplus production model, while the highest RMSE was from Schnute model. However, the highest coefficient of determination ($R^2$) was from the ME model, but the ASPIC model yielded the lowest coefficient. On the other hand, the MSY of Kapenta (Limnothrissa miodon) ranged from 16,880 mt by ASPIC model to 25,373mt by ME model, and $f_{MSY}$, from 94,580hauls by ASPIC model to 225,490hauls by Schnute model. In this case, both the lowest root mean square error (RMSE) and the highest coefficient of determination ($R^2$) were obtained from the ME model, which showed relatively better fits of data to the model, indicating that the ME model is statistically more stable and robust than other models. Moreover, the ME model could provide additional ecologically useful parameters such as, biomass at MSY ($B_{MSY}$), carrying capacity of the population (K), catchability coefficient (q) and the intrinsic rate of population growth (r).

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.254-257
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• 2006

In the last few years, ductile fracture criteria based on various hypotheses have been developed and utilized with FEM to predict forming failure. The accurate deformation analysis by the FEM and the decision of damage parameters are the most important factors in these approaches. In this paper, several conventional integral forms of fracture criteria were introduced and the test method to determine damage parameters by using notched specimen was suggested. Based on the results, damage parameters obtained under the different stress system (tensile and compression) are compared and analyzed.

• 한국정밀공학회지
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• 제19권10호
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• pp.147-155
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• 2002

In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.

• 한국지반공학회지:지반
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• 제9권4호
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• pp.93-102
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• 1993

연약 지반위에 축조된 토질 구조물은 제체의 자중으로 인하여 오랜 기간 동안 침하가 계속되는데 이는 시간표존적 거동인 압밀과 크리프(creep)가 동시에 작용하여 발생된다. 본 연구에서는 안산의 해성점토에 대하여 크리프거동 해석에서 필요한 정수를 구하고 수치해석시 중요시되고 있는 구속응력과 응력수준에 따른 크리프정수의 영향 특성에 대하여 연구하였다. 그 결과 탄성계수 E1과 크리프정수 n는 적용응력 수준에 영향을 받는 것으로 나타나 응력수준에 따른 크리프정수 결정식을 제시하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.107-111
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• 2009

The parameters in the Horton's model which has well known as typical infiltration model were determined by the use of the optimization technique. It was assumed the initial infiltration capacity in this model was related to the antecedent precipitation per 10 days with linear combination. And both the parameters of the ultimate infiltration capacity and the decay factor were determined uniquely on a basin. Thus the optimal model's parameters representative to a basin were obtained and the Horton's infiltration equations by rainstorm events were determined. The data of ten rainstorm events for this study were observed at the Jeonjeokbigyo station located at the Selmacheon experimental basin that was $8.5\;km^2$ wide in the Imjin river.

• 융합정보논문지
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• 제11권10호
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• pp.10-19
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• 2021

본 논문은 뇌파 측정 및 분석을 통해 정신적 피로를 반영하는 특징 파라미터를 도출하고자 하였다. 이를 위해 30분간 눈을 감은 편안한 안정 상태와 뺄셈연산을 암산으로 수행하는 작업을 통해 정신적 피로를 유도하였다. 5명의 피험자가 실험에 참가하였으며, 피험자들은 모두 대학 재학 중인 오른손잡이 남학생들이며 평균 나이는 25.5세이다. 정신적 피로를 반영하는 특징 파라미터 도출을 위해 실험 처음과 마지막에서 수집된 뇌파에 대해 스펙트럼분석을 수행하였다. 분석 결과, 정신적으로 피로할수록 후두엽 및 측두엽 위치에서 알파대역의 절대파워는 증가한 반면 상대파워는 감소하였다. 또한 안정 상태와 작업 상태간 파워 차이는 절대파워에 비해 상대파워가 크게 나타났다. 이 결과는 후두엽 및 측두엽 위치에서의 알파 상대파워가 정신적 피로를 반영하는 특징 파라미터임을 나타낸다. 본 연구 결과는 운전 중 피로 및 졸음 판단과 같은 정신적 피로 판별을 위한 자동화시스템 개발을 위한 특징 파라미터로 활용될 수 있다.