In this study, the ultra-smooth surface of Inconel 625 workpieces were achieved by 40000-RPM grade magnetic abrasive polishing (MAP) process. This process created the high rotational speed of workpiece and the movement of magnetic pole to produce the polishing action of magnetic abrasive tools on the surface of Inconel 625 workpieces. The input parameters used in this experiment were selected as the rotational speed of workpiece (40000 rpm), movement of magnetic poles (Feed rate: 2 mm/sec), grain size of abrasive tool (PCD abrasive: 1- ㎛), magnetic poles (A-shape, B-shape, and C-shape) and the polishing times (0, 2, 4, 6, 8, 10, 12, 14 min). The results of this study showed that the smooth surface of Inconel 625 bar was achieved, which the surface roughness of Inconel 625 were significantly improved from 0.33 μm to 0.03 μm within 10 min of the polishing time via B-shape of magnetic poles. This can be confirmed that the 40000-RPM grade MAP processing method is an effective process to achieve high surface quality of Inconel 625 workpieces.

If the release point of the precision air delivery system is determined only by L/D, target accuracy can be greatly reduced due to changes in wind speed and direction by altitude. In this paper, after conducting a self-made precision air delivery system (PADS) drop test, we analyzed the problems that may occur due to wind changes by altitude and proposed an algorithm to determine the release point of PADS to increase the precision of PADS landing. As a result of conducting the simulation with this algorithm, it was similar to the results of the drop experiment. In addition, the conceptual design of HW and SW was carried out for the actual dropsonde implementation in the future.

필립 펄스타인(Philip Pearlstein, 1924-2022)은 미국 현대의 정밀-사실주의 (Sharp-Focus Realism) 작가이다. 1949-1950년 작가 활동을 시작한 펄스타인은 당시 미국의 주류 미술인 추상표현주의의 영향을 받았다. 그러다 1960년대 추상표 현주의에 회의를 느끼고 인체 누드를 주제로 구상 회화를 본격적으로 시작했다. 펄스 타인의 누드화는 극(極)사실적이면서도 추상적인 구성을 통해 독창적인 조형성을 보 여준다. 이에 본 논문에서는 펄스타인의 정밀-사실주의 누드화에 나타난 추상적 구 성의 특징과 그 기원을 살펴보고자 한다. 펄스타인의 정밀-사실주의 누드화는 화면의 모든 부분이 동등한 초점으로 묘사 된다. 그는 누드화의 인체, 사물, 공간을 전통적인 원근법이 아닌 동일 선명도로 표 현하여 화면은 평면의 탈중심적이 된다. 이러한 특징은 1970년대 미국 하이퍼리얼 리즘 회화와 유사하지만 펄스타인은 사진을 사용하지 않았다. 펄스타인에게는 대상 뿐 아니라 대상을 둘러싼 외부 조건의 변화와 우연성을 포착하는 것이 작품에 중요 한 요소였다. 그는 대상을 직접 눈으로 관찰하여 사진을 기반으로 하는 하이퍼리얼리 즘과는 다른 방식의 사실주의를 추구했다. 펄스타인의 직접 관찰을 통한 묘사는 화면에서 작가의 주관적인 감성이나 의미를 배제하는 요인이 되었다. 펄스타인은 회화가 기술이 성취된 형식만으로도 충분히 예 술적 가치를 실현할 수 있다고 생각했다. 그는 최대한 객관적 시선을 통해 작품을 제 시할 뿐이다. 그 형식에서 의미를 찾고 감동하는 것은 감상자의 몫이다. 이후 펄스타 인은 인체와 사물을 상징적으로 나타내는 대신 중립적 개체로 표현하여 화면을 구성 하는 요소로 사용했다. 1980-1990년대 펄스타인 누드화의 특징은 정밀-사실주의 기법 화면에 추상적 구성이 적극적으로 나타나는 것이다. 펄스타인은 추상표현주의와 모더니즘 회화의 영향으로 특히, 몬드리안의 수평적 확장과 리듬감, 클라인의 추상화된 선적인 구성은 그의 누드화 조형성에 영향을 주었다. 여기에 동양 회화의 여백과 같은 공간성을 자 기 누드화에 적용하여 3차원의 공간을 형성했다. 펄스타인은 모더니즘 추상 조형성 을 누드화에 활용하였으나 반드시 평면에 도달해야 한다는 생각에서는 자유로웠다. 그 결과 1980-1990년대 펄스타인의 누드화는 인체, 사물, 공간을 정밀-사실주의 기 법으로 표현하면서 구성에서는 모더니즘 추상의 평면성과 화면 내부와 외부로 확장 되는 3차원의 공간성을 동시에 성취하게 되었다. 1980-1990년대 펄스타인의 정밀-사실주의 누드화는 추상표현주의와 모더니즘 의 영향을 받으면서도 자기 눈으로 관찰된 3차원의 공간을 보이는 그대로 받아들여 화면에 담아내는 독자적인 조형성을 성취했다. 이것은 펄스타인이 사실적 재현과 추 상적 구성을 넘어서 자기만의 예술적 깊이를 추구한 것으로, 주류 미술과 대중적 기 대를 넘어 자기만의 예술 세계를 끊임없이 창조해 나간 결과라고 생각된다.

In this paper, we deal with the design of a model predictive control (MPC) for precise speed servo control of DC motor systems. The proposed controller is designed in the form of optimal control that calculates and outputs the optimized control input under constraints for each sampling. In particular, MPC designs the control inputs in advance for each sampling and predicts the outputs using them. Thus, it shows excellent control performance even in the case of disturbance or model uncertainty. The effectiveness of the proposed controller was demonstrated through computer simulations using MATLAB/Simulink and DC motor experimental system using real time controller. Moreover, the effectiveness of the proposed controller was confirmed by comparing its control performance with PID controller, which was tested under the same experimental condition as the MPC.

In this study, data on indication errors within the range of 0 to 10 mm were measured using a dial gauge, which is widely used as a comparative measuring instrument in the field. Using Minitab, a statistical program, measurement conditions were determined during calibration of measuring instruments. Since the P value of the test statistic for the indication error is 0.000 to 0.003, the alternative hypothesis (H1) that no significant difference occurs due to a change in the measurement point at the significance level of 0.05 was adopted.

Fouling is an inevitable problem in membrane water treatment plant. It can be measured by trans-membrane pressure (TMP) in the constant flux operation, and chemical cleaning is carried out when TMP reaches a critical value. An early fouilng alarm is defined as warning the critical TMP value appearance in advance. The alarming method was developed using one of machine learning algorithms, decision tree, and applied to a ceramic microfiltration (MF) pilot plant. First, the decision tree model that classifies the normal/abnormal state of the filtration cycle of the ceramic MF pilot plant was developed and it was then used to make the early fouling alarm method. The accuracy of the classification model was up to 96.2% and the time for the early warning was when abnormal cycles occurred three times in a row. The early fouling alram can expect reaching a limit TMP in advance (e.g., 15-174 hours). By adopting TMP increasing rate and backwash efficiency as machine learning variables, the model accuracy and the reliability of the early fouling alarm method were increased, respectively.

This study proposes a methodology for assessing seismic liquefaction hazard by implementing high-resolution three-dimensional (3D) ground models with high-density/high-precision site investigation data acquired in an area of interest, which would be linked to geotechnical numerical analysis tools. It is possible to estimate the vulnerability of earthquake-induced geotechnical phenomena (ground motion amplification, liquefaction, landslide, etc.) and their triggering complex disasters across an area for urban development with several stages of high-density datasets. In this study, the spatial-ground models for city development were built with a 3D high-precision grid of 5 m x 5 m x 1 m by applying geostatistic methods. Finally, after comparing each prediction error, the geotechnical model from the Gaussian sequential simulation is selected to assess earthquake-induced geotechnical hazards. In particular, with seven independent input earthquake motions, liquefaction analysis with finite element analyses and hazard mappings with LPI and LSN are performed reliably based on the spatial geotechnical models in the study area. Furthermore, various phenomena and parameters, including settlement in the city planning area, are assessed in terms of geotechnical vulnerability also based on the high-resolution spatial-ground modeling. This case study on the high-precision 3D ground model-based zonations in the area of interest verifies the usefulness in assessing spatially earthquake-induced hazards and geotechnical vulnerability and their decision-making support.