• 한국환경보건학회지
• /
• 제36권4호
• /
• pp.313-322
• /
• 2010

The aim of this research was to apply experimental design methodology to optimization of conditions of electrochemical oxidation of Rhodamine B (RhB) and N, N-Dimethyl-4-nitrosoaniline (RNO, indicative of the OH radical). The reactions of electrochemical oxidation of RhB degradation were mathematically described as a function of the parameters of current ($X_1$), NaCl dosage ($X_2$) and pH ($X_3$) and modeled by the use of the central composite design. The application of response surface methodology (RSM) yielded the following regression equation, which is an empirical relationship between the removal efficiency of RhB and RNO and test variables in a coded unit: RhB removal efficiency (%) = $94.21+7.02X_1+10.94X_2-16.06X_3+3.70X_1X_3+9.05X_2X_3-{3.46X_1}^2-{4.67X_2}^2-{7.09X_3}^2$; RNO removal efficiency (%) = $54.78+13.33X_1+14.93X_2- 16.90X_3$. The model predictions agreed well with the experimentally observed result. Graphical response surface and contour plots were used to locate the optimum point. The estimated ridge of maximum response and optimal conditions for the RhB degradation using canonical analysis was 100.0%(current, 0.80 A; NaCl dosage, 2.97% and pH 6.37).

• 한국항만경제학회지
• /
• 제28권1호
• /
• pp.289-312
• /
• 2012

세계 국제 화물 무역의 80% 이상이 해상운송을 통하여 운송되고 있다. 그래서 국제무역량이 많은 국가들은 해운산업의 중요성을 인식하고 자국의 해운산업을 육성하기 위한 정책을 추진해왔다. 최근 세계 경제, 국제무역, 세계 원유 가격 및 다른 불확실적인 요소들의 변화로 인하여 세계 해운 시장에 있어 경쟁이 더욱 심해지고 있다. 해안선에 많이 접해 있고 해외 경제의존도가 높은 국가인 태평양 연안 국가 예를 들어 일본, 중국, 한국의 해운산업은 최근 비약적인 발전을 해 오고 있다. 특히 중국은 급속히 증가하는 무역량을 바탕으로 해운산업의 성장이 급속도로 이루어지고 있다. 이에 본 연구는 태평양 연안에 속해 있는 주요 해운국가인 일본, 중국, 한국, 싱가포르, 미국의 해운산업의 국제 경쟁력을 상호 비교하며 중국 해운산업에 경쟁력에 대한 강화방안을 제시하는 데 있다. M. Porter의 다이아몬드 모델을 바탕으로 AHP분석 방법을 통한 해운경쟁력 요소를 도출하고 이를 통해 주요 해운국과 중국 해운산업의 경쟁력을 비교해 본 결과 해운산업의 질적 요소에서 취약하기 때문에 이에 대한 개선 정책이 필요할 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.42-45
• /
• 2002

General wheel mark in mono-crystalline silicon wafer finding is able to be expected because it depends on radius ratio and angular velocity ratio of wafer and wheel. The pattern is predominantly determined by the contour of abrasive grits resulting from a relative motion. Although such a wheel mark is made uniform pattern if the process parameters are fixed, sub-surface defect is expected to be distributed non-uniformly because of characteristic of mono-crystalline silicon wafer that has diamond cubic crystal. Consequently it is considered that this phenomenon affects the following process. This paper focused on kinematic analysis of wafer grinding process and simulation program was developed to verify the effect of process variables on wheel mark. And finally, we were able to predict sub-surface defect distribution that considered characteristic of mono-crystalline silicon wafer

• 수산경영론집
• /
• 제46권2호
• /
• pp.1-11
• /
• 2015

Due to the environmental changes such as decreasing and aging fishing population and increasing imported marine products, improvement of fishing business competitiveness has become one of important issues. This study aimed to analyze the coastal fishing business units in Busan region and compare their business performances in order to find out success factors. The logistic regression analysis between 4 determination factors of competitiveness and business performances showed that the ship tonnage in the factor conditions, catch of species of fishing types'kg per price in the demand conditions, cooperative sales ratio in the related & supporting industries, and net per cost in the firm strategy, and structure & rivalry had the positive(+) impacts on business performances.

• 대한기계학회논문집A
• /
• 제26권7호
• /
• pp.1270-1279
• /
• 2002

Residual stress is a dominant obstacle to efficient production and safe usage of device by deteriorating the mechanical strength and failure properties. Therefore, we proposed a new thin film stress-analyzing technique using a nanoindentation method. For this aim, the shape change in the indentation load-depth curve during the stress-relief in film was theoretically modeled. The change in indentation depth by load-controlled stress relaxation process was related to the increase or decrease in the applied load using the elastic flat punch theory. Finally, the residual stress in thin film was calculated from the changed applied load based on the equivalent stress interaction model. The evaluated stresses for diamond-like carbon films from this nanoindentation analysis were consistent with the results from the conventional curvature method.

• Applied Microscopy
• /
• 제46권3호
• /
• pp.167-169
• /
• 2016

Solder/electroless nickel immersion gold (ENIG) joint sample which is comprised of dissimilar materials with different mechanical properties has limited the level of success in preparing thin samples for transmission electron microscopy (TEM). This short technical note reports the operation parameters for ultramicrotomy of solder joint sample and TEM analysis results. The solder joint sample was successfully sliced to 50~70 nm thick lamellae at slicing speed of 0.8~1.2 mm/s using a boat-type $45^{\circ}$ diamond knife. Ultramicrotomy can be applied as a routine sample preparation technique for TEM analysis of solder joints.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.266-269
• /
• 2002

Research during the past several years has established the effectiveness of acoustic emission (AE)-based sensing methodologies for machine condition analysis and process. AE has been proposed and evaluated for a variety of sensing tasks as well as for use as a technique for quantitative studies of manufacturing process. STD11 has been known as difficult-to-cut materials. For this study, the micro-grooving machine was developed. The experiments were performed using diamond blade and CBN blade f3r machining STD11. Evaluating the machining conditions, frequency spectrum analysis of acoustic emission (AE) signals according to each conditions were applied.

• 산업기술연구
• /
• 제14권
• /
• pp.119-125
• /
• 1994

Ultra-precision machine tool equipped with the diamond bite tip is used to machine optical products, drums of VTR or computer hard disk. It needs nano technology in the surface roughness of workpiece. To perform the nano scale machining, ultra-precision machine tool must be designed and manufactured in consideration of the vibration characteristics. In this paper, using the finite element analysis, we investigate the modal parameters of the ultra-precision machine tool structures, which use cast iron, granite and alumina ceramic for the bed materials. To verify the numerical results, we manufacture a model of ultra-precision machine tool using granite bed and perform impulse test. Through the theoretical and experimental analyses, we could compare and estimate the vibration characteristics of the three models for the ultra-precision machine tools.

• 한국기계가공학회지
• /
• 제9권1호
• /
• pp.87-92
• /
• 2010

Micromachining technology using a ultra-precision micromachining system is widely applied in the fields of optics, biotechnology and analytical chemistry, etc. specially in microfabrication of fresnel lens, light guide panels of TFT-LED and PDP ribs with micro-patterns, machining errors have an effect on the performance of those products. The deflection of tool and tool holder is known to be one of the very important factors that is due to machining errors in micromachining. The deflections of diamond tool and tool holder used in micro-grooving are analysed by FEM. We analysed by FEM. With an linearity valuation of FEM, deflection of tool and tool holder is calculated by using the data of cutting force which is acquired from micro-V groove machining experiments in micromachining system.

• 한국정밀공학회지
• /
• 제21권3호
• /
• pp.139-146
• /
• 2004

In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation scratch test was studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass 7740) were used as specimens, and forming conditions to reduce the elastic recovery and pile-up were proposed. The indenter was modeled as a rigid surface. Minimum mesh sizes of specimens are 1-l0nm. Variables of the nanoindentation scratch test analysis are scratching speed, scratching load, tip radius and tip geometry. The nano-indentation scratch tests were performed by using the Berkovich pyramidal diamond indenter. Comparison between the experimental data and numerical result demonstrated that the FEM approach can be a good model of the nanoindentation scratch test. The result of the investigation will be applied to the fabrication of the hyper-fine pattern.