• 대한기계학회논문집
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• 제19권6호
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• pp.1411-1421
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• 1995

A rigid visco-plastic finite element method has been developed for modeling superplastic forming processes. The optimum pressure-time relationship for a target strain rate and thickness distributions was predicted using two-node line element based on membrane approximation for plane strain and axisymmetric condition. Analysis of superplastic forming was carried out using the developed program and the numerical results were compared to the values available in the literature for plane strain problems. For description of the contact between the dies and sheet, the direct projection method was applied to the complicated problem and the validity of the scheme was tested. Experiments for the various geometries such as hemisphere and cone were performed with the developed forming machine using the calculated optimum pressure-time curves. Comparison between analysis and experiments showed good agreement.

• 지식경영연구
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• 제20권2호
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• pp.137-153
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• 2019

This study aim to identifying important determinants of happiness from university students' view point. To identify the determinants of happiness, focus group interviews were conducted. After carrying content analysis, five main categories were identified: 'Enjoying the present(enjoy the hobby, group activities and trivial things)', 'Self-regulation not dictated by anyone', 'Pursuing self-generated personal goals(goal-oriented, process-oriented)', 'Enjoying hassle-free moment(physical comport, psychological comforts being alone), 'Forming a good relationships (wide range of relationships, quality of relationships). This result is expected to provide deep understanding of students' happiness in planning programs and policies.

• 소성∙가공
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• 제21권6호
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• pp.378-383
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• 2012

Laser forming is an advanced process in sheet metal forming in which a laser heat source is used to shape the metal sheet. This is a new manufacturing technique that forms the metal sheet only by a thermal stress. Analyses of the temperature and stress fields are very important to identify the deformation mechanism in laser forming. In this paper, temperature distributions and deformation behaviors of DP980 steel sheets are investigated numerically and experimentally. FE simulations are first conducted to evaluate the response of a square sheet in bending. The effects of process parameters such as laser power and scanning speed are then analyzed numerically and experimentally. It is observed that experimental and numerical results are in good agreement. These results provide a relationship between the line energy and the angles for laser bending of DP980 steel sheets.

• 한국주조공학회지
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• 제18권5호
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• pp.481-487
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• 1998

Shell sand is widely used to make a complex shape castings due to its good collapsibility. When molten metal is poured into the mold, various gases are generated by the thermal decomposition of binder in the shell core. Casting defects such as blow hole and blister come from these gases. If it is possible to predict the evolution of gas quantitatively, it may provide effective solutions for minimizing the casting defects. To examine the gas evolution by shell core quantitatively, casting experiment and calculation were carried out. Gas pressure and gas volume evolved by shell core were measured in the experiment, and temperature distribution in the shell core was obtained by heat transfer analysis. From the result above, prediction on the gas volume evolved during pouring was tried. As forming pressure of the shell core increased and forming temperature decreased, the gas evolution increased. There was a close relationship between the calculated gas volume evolved and the measured one.

• 오토저널
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• 제12권1호
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• pp.40-48
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• 1990

Bake hardenability of batch annealed steel sheets is investigated in connection with the amount of tensile deformation and the bake hardening condition. This study associates with the method for producing bake hardening materials by means of batch annealing process and for measuring bake hardenability which is not yet fully established. The experimental result demonstrates the relationship between strain distribution and bake hardening behavior in various bake hardening conditions, which provides an essential information for automobile design and related sheet metal forming in a press shop. The result also shows the bake hardenability of the tested material increases as the baking temperature is increased from 150.deg. C. The result assures the bake hardening materials can guarantee reasonably high strength as well as good uniformity in yield strength for the automobile body by sheet metal forming process.

• 대한기계학회논문집
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• 제8권2호
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• pp.111-118
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• 1984

본 연구에서는 상계해 이론으로부터 마찰 상수 m에 대한 해석을 시도하여 조 직의 치밀화, 링의 내경감소율 등의 소결금속에 대한 성형특성을 여러가지 상대밀도, 마찰상수에 대해서 계산했다. 실험은 철 분말 소결금속인 시편을 상대밀도가 0.75, 0.85, 0.9이고 링의 외경:내경:높이의 비가 6:3:1과 6:3.1:1.5로 제작했고, 평 금형 (parallel platens) 사이에서 여러가지 윤활상태로 시행하여 그 실험치와 이론치들을 비교 하였다.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1613-1624
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• 2007

첫인상이 대인관계에 있어서 유연성을 갖기 때문에 첫인상은 $4{\sim}10$초 정도의 짧은 시간에 결정되어진다고 볼 수 있다. 첫 만남에서 결정된 이미지를 새롭게 바꾸려 할 때에는 많은 시간과 노력이 필요하며 첫 만남에서 호감과 신뢰를 갖도록 하는 '라포형성'은 고객관리에 있어 매우 중요한 요소 중 하나이다. 본 논문은 이러한 경영환경의 변화에 따른 시대적 요구에 따라 고객만족경영에 매우 중요한 '라포 형성'에 관해 연구, 이를 상품판매 현장에 적용하여 판매 제고를 도모코자 한다. 본 연구를 위해서 인간 성격체계 중 가장 효과적인 도구로 평가되는 9가지 성격유형을 설명하는 '에니어그램'을 활용하였고 9가지 유형들의 각 특성 중에서 판매현장에서 적용가능 하리라 판단되는 특성들을 선별하고 이 요인들은 판매현장에서의 라포형성에도 영향을 미칠 것이라는 생각했다. 그리고 한국에니어그램 영성연구소에서 설문과 워크숍을 통해 자기 유형을 찾은 사람들 375명을 대상으로 설문을 통해 적용여부를 증명하였다.

• 전자공학회논문지A
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• 제28A권12호
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• pp.46-52
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• 1991

A new signal process circuit using two ISFETs as the input devices of the MOS differential amplifier stage for an ISFET biosensor has been developed. One chip integration of the newly developed signal process circuit, ISFETs and a Pt quasi-reference electrode has been carried out according to modified LOCOS p-well CMOS process. The fabricated chip showed gains of 0.8 and 1.6, good liniarity in the input-output relationship and very small power dissipation, 4mW. The chip was applied to realize a urea sensor by forming an immobilized urease membrane, using lift-off technique. on the gate of an ISFET. The urea sensor chip showed stable responses in a wide range of urea concentrations.

• Archives of Pharmacal Research
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• 제15권2호
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• pp.169-175
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• 1992

Anti-inflammatory glucocorticoid (GC) derivatives have been clinically used in immune-malfunctional diseases for their immunosuppressive activity. However, there is still a lack of knowledge on the relationship between anti-inflammatory and immunosuppressive activities. In order to compare immunosuppressive activities with the known anti-inflammatory activities of the GC derivatives, eight clinically used GC derivatives including hydrocortisone, prednislone, 6$\alpha$-methyl prednisolone, triamcinolone, dexamethasone, betamethasone, triamcinolone acetonide and fluocinolone acetonide were selected, and lymphoblastosis inhibition and plaque-forming cell (PFC) response in mice were studied as immunological parameters. In Con A-induced lymphoblatosis inhibition invitro, all derivatives showed potent inhibition $IC_{50}$ values of the derivaties except methyl prednisolone and triamcinolone were less than $10^{-7}$M and good dose dependency was obtained. This result was well correlated with that of their anti-inflammatory potencies obtained. This result was well correlated with that of their anti-inflammatory potencies and their receptor binding affinities. However, in PFC response, consistent result were not obtained. Total numbers of PFCs per spleen were decreased by some derivatives, but numbers of PFCs per $10^6$ cells were not decreased by systemic administration of but numbers of PFCs per $10^6$ cells were not decreased by systemic administration of GC at the dose of 0.05 mg/mouse. Furthermore, at the dose of 0.1 mg/mouse, numbers of PFCs per $10^6$ cells were found to be increased, although total PFCs per spleen were decreased.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.199-202
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• 2004

In this present study, an attempt was made to determine the deformation mode of the Zr-Ti-Cu-Ni-Be bulk metallic glass by compression test over a wide range of temperatures and strain rates. From the results, empirical deformation map could be constructed including the boundaries of different deformation modes. Considering power dissipation map and instability map developed on the basis of the Dynamic Materials Model (DMM), the processing map for extrusion could also be constructed. In addition, the macroscopic formability of this BMG alloy has also been examined through the extrusion in laboratory scale within undercooled liquid state. From the results of macroscopic extrusion formability, both deformation map and processing map present good criteria to determine optimal forming conditions.