• 센서학회지
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• 제31권1호
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• pp.57-63
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• 2022

This study describes a system that monitors the tool and cutting state of automatic beveling operation in real time. As a signal for cutting state monitoring, a motor current detected from the spindle drive system of the automatic beveling machine is used to monitor abnormal state. Because automatic beveling is processed using a face milling cutter, the cutting force mechanism is the same as the milling process. The predicted cutting torque is obtained using a cutting force model based on specific cutting resistance. Then, the predicted cutting torque is converted into the spindle motor current value, and cutting state stability is diagnosed by comparing it with the motor current value detected during beveling operation. The experimental results show that the spindle motor current can detect abnormal cutting state such as overload and tool wear during beveling operation, and can diagnose the cutting stability using the proposed equip-current line diagram.

• 대한기계학회논문집A
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• 제30권11호
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• pp.1439-1446
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• 2006

The fatigue test of the fillet weldments was executed with different beveling angles and porosities. The beveling angles of $0^{\circ}$, $45^{\circ}$ and $55^{\circ}$ were compared with fatigue lives. After the fillet weldment failure, the porosities which found at the fractured surface were observed to account the effect on fatigue life. Finite element analysis was performed to correlate the fatigue strength and the sizes and the locations of porosities. The stress-strain field was severely affected by the length of notch and the sizes and locations of porosities. Based on the quantitative analysis of porosity effect, the total volume of porosities was a key factor for fatigue strength of the fillet weldment.

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2202-2209
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• 2009

모관과 지관의 다양한 접합형상에 대하여 접합궤적을 수학적으로 유도하였다. 이 접합궤적에 용접부의 루트갭 및 절단폭 등을 보정하여 실제적으로 절단궤적을 결정하여 NC 코드를 생성하고 그 경로를 확인하기 위하여 ghost 기능을 구현하였다. 척회전인 C축의 8개 구간별로 A, B축의 Tilting을 사용하여 개선 기능을 구현하였으며, 이는 절단궤적을 따라서 절단하면서 동시에 개선이 가능하도록 6축 CNC 파이프 코스터 전용 CAM 프로그램을 개발하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.149-150
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• 2005

Thyristor breakdown voltage variation acceleration aging test was investigated. The breakdown voltage was deceased after 1000 hours acceleration aging test. It temperature rising caused by electric field concentration at the edge beveling region of the thyristor was confirmed using Silvaco device simulation. The local temperature rising is driving force for the defect propagation. Consequently, propagated defects of the beveling region seems to decrease thyristor's breakdown voltage.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.120.1-120.1
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• 2005

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.17-30
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• 2022

The use of composite patches for the reduction of stresses at the level of the damaged zone in aeronautical structures has experienced rapid expansion given its advantages over conventional mechanical processes (riveting, bolting, etc.). Initially, The research axes in this field were aimed at choosing suitable mechanical properties for the composite and the adhesive, then to optimize the shape of the composite patch in order to ensure good load transfer and avoid having a debonding at the level of the edges essentially for the case of a repair by single side where the bending moment is present due to the non-symmetry of the structure. Our work falls within this context; the objective is to analyze by the finite element method the fracture behavior of a damaged plate repaired by composite patch. Stress reduction at the edge is accomplished by creating a variable angle chamfer on the composite patch. The effects of the crack length, the laminate sequence and the nature of the patch as well as the use of a hybrid patch were investigated. The results show clearly that a beveled patch reduces the stress concentrations in the damaged area and even at its edges. The hybrid patch also ensures good durability of the repair by optimizing its stacking sequence and the location of the different layers according to the fibers orientations.

• Restorative Dentistry and Endodontics
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• 제14권2호
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• pp.31-37
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• 1989

The purpose of these study was to compare the sealing ability of a injection-molded thermoplasticized gutta-percha and silver amalgam as retroseal material in vitro. Sixty two upper and lower extracted human teeth with single root were randomly selected and instrumented in a conventional method with H-file. After instrumentation the root canal was obturated with gutta-percha by lateral condensation technique with AH26 and an apicoectomy was performed by beveling the root tip 45 angle. In the experimental group 1 and 2, a class I preparation was made and filled with silver amalgam or gutta-percha and in the experimental group 3 an apicoectomy only was performed. All specimens were immersed in black Indian ink, decalcified and cleared. The depth of dye penetration into the canals were evaluated by califer. The results were as follows ; 1. The experimental group 1 displayed the smallest mean dye penetration as 0.45mm. 2. The experimental group 3 displayed the greatest mean dye penetration as 0.65mm. 3. There was the difference in dye penetration between each group, but the difference was not statistically significant(P>0.05).

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권1호
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• pp.34-39
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• 2006

In high-voltage devices such as thyristor, beveling is mostly used junction termination method to reduce the surface electric field far below the bulk electric field and to expand the depletion region thus that breakdown occurs in the bulk of the device rather than at the surface. However, coating material used to protect the surface of the device contain so many charges which affect the electrical characteristics of the device. And device reliability is also affected by this charge. Therefore, it is needed to analyze the effect of surface charge on electrical characteristics of the device. In this paper, we analyzed the breakdown voltage and leakage current characteristics of the thyristor as a function of the amount of surface charge density. Two dimensional process simulator ATHENA and two-dimensional device simulator ATLAS is used to analyze the surface charge effects.

• Steel and Composite Structures
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• 제32권5호
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• pp.571-582
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• 2019

This study aimed to assess the feasibility on the wide and long 9%Ni steel plate for use in the LNG storage inner tank shell. First, 5-m-wide and 15-m-long 9%Ni steel plates were test manufactured from a steel mill and specimens taken from the plates were tested for strength, toughness, and flatness to verify their performance based on international standards and design specifications. Second, plates with a thickness of 10 mm and 25 mm, a width of 4.8~5.0 m, and a length of 15 m were test fabricated by subjecting to pretreatment, beveling, and roll bending resulting in a final width of 4.5~4.8 m and a length of 14.8m with fabrication errors identical to conventional plates. Third, welded specimens obtained via shield metal arc welding used for vertical welding of inner tank shell and submerged arc welding used for horizontal welding were also tested for strength, toughness and ductility. Fourth, verification of shell plate material and fabrication was followed by test erection using two 25-mm-thick, 4.5-m-wide and 14.8-m-long 9%Ni steel plates. No undesirable welding failure or deformation was found. Finally, parametric design using wide and long 9%Ni steel plates was carried out, and a simplified design method to determine the plate thickness along the shell height was proposed. The cost analysis based on the parametric design resulted in about 2% increase of steel weight; however, the construction cost was reduced about 6% due to large reduction in welding work.

• Restorative Dentistry and Endodontics
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• 제12권1호
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• pp.119-129
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• 1986

The purpose of this study was to evaluate the marginal leakage of glass ionomer cement with different cavosurface margins. 192 class V cavities were prepared on freshly extracted non-carious teeth and glass ionomer cement were inserted according to the manufacturer's instructions. Cavity preparations for this investigation were performed in four groups. The experimental specimens were made by packing the glass ionomer cement (Fuji Ionomer Type II G-C Co. Japan) into the prepared 192 cavities of four groups with different modes: Group I. - The 48 cavities with $90^{\circ}$ butt-joint cavosurface preparation and restored with glass ionomer cement. Group II. - The 48 cavities with butt-joint preparation modified by $135^{\circ}$ beveling the cavosurface in the dentin and restored with glass ionomer cement. Group III. - The 48 cavities with butt-joint preparation modified by cutting a chamfer in the dentin and restored with glass ionomer cement. Group IV. - The same 48 cavities as group I, and overfilled with glass ionomer cement beyond the cavosurface angle. And four groups above described divided into three subgroups by means of conditioning the cavity walls: Control group. - Glass ionomer cement filled in the prepared 64 cavities after being cleaned with a stream of tap water. Phosphoric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% phosphoric acid. Citric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% citric acid. All 192 specimens were immersed in the 2.0% basic fuchsin solution and subjected to thermal stress at one-minute intervals ($4{\pm}2^{\circ}C$ to $60{\pm}2^{\circ}C$) for 70 minutes before exposure to the dye. The specimens were sectioned ecclesiologically through the center of the restorations for different periods of immersion time, 24 hours, 7 days, 14 days 30 days. The sections were examined under a stereoscopic microscope. The results were as follows: 1. The degree of marginal leakage in group II and III was greater than that in group I and IV. 2. The degree of marginal leakage in phosphoric acid treatment group was similar with that in control group. 3. The degree of marginal leakage in citric acid treatment group was less than that in control group. 4. In all groups, the degree of marginal leakage in phosphoric acid treatment group was greater than that in citric acid treatment group. 5. There is no statistical difference of the degree of marginal leakage according to the immersion time in the dye solution.