• 대한기계학회논문집A
• /
• 제34권9호
• /
• pp.1299-1304
• /
• 2010

압연실험을 통해서 폭 방향 변형 편차가 존재하는 실리콘 강판의 가공파손을 고찰하였다. 폭 방향 변형 편차는 강판에 웨이브를 발생시키고 압연방향으로 소재의 에지 부위(혹은 센터 부위)에 인장(혹은 압축)을 준다. 실제 압연기에서 발생하는 웨이브를 실험실적으로 구현하기 위해서 공형롤을 설계 및 제작하였다. 실험에 사용한 소재는 고-실리콘(약 3%) 강판이다. 본 실험을 통해서 센터 웨이브에 의해 발생되는 에지 부위 인장응력이 가공파손에 가장 지배적인 요인이라는 것이 제시되었다. 센터 웨이브를 일으키는 폭 방향 변형 편차의 정도에 따라 에지 파손과 지그재그 형태의 시편 중심 절손을 유발한다는 결과도 도출하였다.

• 해양환경안전학회지
• /
• 제29권4호
• /
• pp.380-388
• /
• 2023

본 연구는 모형선박의 횡방향 무게분포를 변화시키면서 횡요주기 및 관성모멘트에 의한 GM을 추정하고 경사시험으로 계측되는 GM 값과 비교한다. 그 과정에서 각 수치를 분석하여 관계성을 파악한다. 실험 및 비교에 사용된 선박의 종류는 3종류로 7톤급, 20톤급 어선과 KVLCC의 모형선을 사용하였다. 실험은 스윙프레임 테스트와 자유 횡요 감쇠테스트를 수행하여 관성모멘트와 횡요주기를 계측하고, 경사시험으로 GM을 계측하였다. 관성모멘트와 횡요주기로 추정된 GM과 경사시험으로 구해진 GM은 선박의 무게 분포 변화에도 동일한 경향을 보였지만, 경사시험에서 구해진 GM이 더 작은 값을 보였다. 따라서 GM 추정 시에 관성모멘트나 횡요주기 외에도 추가적인 보정 계수나 파라미터가 필요하다고 판단된다. 추후 무게중심을 변화시켜 추정 GM과의 관계를 분석하여 보정 계수를 산출할 계획이다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
• /
• pp.336-345
• /
• 2004

Investigated via a series of finite-element(FE) process simulation is the effect of diverse process variables on some selected non-dimensional parameters characterizing the thermo-mechanical behavior of the roll and strip in hot strip rolling. Then, on the basis of these parameters, on-line models are derived for the precise prediction of the temperature changes occurring in the bite zones as well as in the inter-stand zones in a finishing mill. The prediction accuracy of the proposed models is examined through comparison with predictions from a FE process model.

• 패션비즈니스
• /
• 제1권2호
• /
• pp.20-30
• /
• 1997

The purpose of this study is to examine the influence of European middle class, ethos to costume. This study is concerned with historic situation about enlightment and French revolution, and the change process of costume before and after the French Revolution. In order to investigate the relationship, this studies include the phenomenon of costume in the basis of thoughts of the age (enlightment), political event (French revolution) and social system (middle classes). The Influence of enlightment to costume of man and children were which emphasized practical aspect. Children costume was developed independently from costume of adult before French revolution. French revolution played a roll in silhouette, color, texture of costume for man. Especially pantalons which names Sans-culotte generalized as modern clothing for man. Women freed from corset because of the influence of neo-classicism for a while. However, costume of woman did not change much because women were excluded from of enlightment.

• 한국해양공학회지
• /
• 제38권2호
• /
• pp.43-52
• /
• 2024

Investigating ship motion under real conditions is vital for evaluating the seakeeping performance, particularly in the design process stage. This study examined the influence of the principal particulars of a trawler on its seakeeping performance. The wave conditions in the Bering Sea are investigated using available data. The length-to-beam (L/B) and beam-to-draft (B/T) ratios of the ship are changed by 10% for the numerical simulation. The response amplitude operator (RAO) motion, root mean square (RMS) value and sensitivity analysis are calculated to evaluate the influence of the trawler dimensions on ship motions. The peak RAO motion affected the ship motions noticeably because of the resonance at the natural frequency. The L/B and B/T ratios are important geometric parameters of a ship that significantly influence its RMS motion, particularly in the case of roll and pitch. The change in the B/T ratio has a good seakeeping performance based on a comparison of the roll and pitch with the seakeeping criteria. The present results provide insights into the seakeeping performance of ships due to the influence of the principal dimensions in the design stage.

• 대한기계학회논문집B
• /
• 제27권3호
• /
• pp.275-285
• /
• 2003

A visualization study on the effect of forcing amplitude in tone-excited jet diffusion flames has been conducted. Visualization techniques are employed using optical schemes. which are a light scattering photography. Flame stability curve is attained according to Reynolds number and forcing amplitude at a fuel tube resonant frequency. Flame behavior is globally grouped into two from attached flame to blown-out flame according to forcing amplitude: one sticks the tradition flame behavior which has been observed in general jet diffusion flames and the other shows a variety of flame modes such as the flame of a feeble forcing amplitude where traditionally well-organized vortex motion evolves, a fat flame. an elongated flame. and an in-burning flame. Particular attention is focused on an elongation flame. which is associated with a turnabout phenomenon of vortex motion and on a reversal of the direction of vortex roll-up. It is found that the flame length with forcing amplitude is the direct outcome of the evolution process of the formed inner flow structure. Especially the negative part of the acoustic cycle under the influence of a strong negative pressure gradient causes the shapes of the fuel stem and fuel branch part and even the direction of vortex roll-up to dramatically change.

• 한국정밀공학회지
• /
• 제17권11호
• /
• pp.191-198
• /
• 2000

Laser direct patterning of the coated photoresist (PMER-NSG31B) layer was studied to make halftone dots on gravure printing roll. The selective laser hardening of photoresist by Ar-ion laser(wavelength: 333.6~363.8nm) was controlled by the A/O modulator. The coating thickness in the range of 5~11$\mu m$ could be obtained by using the up-down directional moving device along the vertically located roll. The width, thickness and hardness of the hardened lines formed under the laser power of 200~260㎽ and irradiation time of 4.4~6.6 $\mu$sec/point were investigated after developing. The hardened width increased as the coating thickness increased. Though the hardened thickness was changed due to the effect of the developing solution, the hardened layer showed good resistance to the scratching of 2H pencil. Also, the hardened minimum line widths of 10$\mu m$ could be obtained. The change of line width was also found after etching, and the minimum line widths of 6$\mu m$ could be obtained. The hardened lines showed the good resistance to the etching solution. Finally, the experimental data could be applied to make gravure halftone dots using the developed imaging process, successfully.

• 대한금속재료학회지
• /
• 제50권12호
• /
• pp.939-948
• /
• 2012

A 3-ply clad metal consisting of aluminum and copper was fabricated by roll bonding process and the microstructures and mechanical properties of the roll-bonded and post-roll-bonding heat treated Cu/Al/Cu clad metal were investigated. A brittle interfacial reaction layer formed at the Cu/Al interfaces at and above $400^{\circ}C$. The thickness of the reaction layer increased from $12{\mu}m$ at $400^{\circ}C$ to $28{\mu}m$ at $500^{\circ}C$. The stress-strain curves demonstrated that the strength decreased and the ductility increased with heat treatment up to $400^{\circ}C$. The clad metal heat treated at $300^{\circ}C$ with no indication of a reaction layer exhibited an excellent combination of the strength and ductility and no delamination of layers up to final fracture in the tensile testing. Above $400^{\circ}C$, the ductility decreased rasxpidly with little change of strength, reflecting the brittle nature of the intermetallic interlayers. In Cu/Al/Cu clad heat treated above $400^{\circ}C$, periodic parallel cracks perpendicular to the stress axis were observed at the interfacial reaction layer. In-situ optical microscopic observation revealed that cracks were formed in the Cu layer due to the strain concentration in the vicinity of horizontal cracks in the intermetallic layer, promoting the premature fracture of Cu layer. Vertical cracks parallel to the stress axis were also formed at 15% strain at $500^{\circ}C$, leading to the delamination of the Cu and Al layers.

• 한국항공우주학회지
• /
• 제48권11호
• /
• pp.927-933
• /
• 2020

본 논문에서는 항공기 자세 변화를 고려한 항공기 보조연료탱크 연료량측정시스템을 제시하였다. 개발된 연료량측정시스템은 연료센서, 데이터 처리장치, 계기 및 센서 데이터로부터 연료량을 추정하는 소프트웨어로 구성되었다. 지상에서의 롤 및 피치 자세 변화를 모사하기 위해 모사시험 장치가 개발되었다. 모사시험장치를 이용하여 다양한 연료량, 롤 및 피치 각도의 센서 데이터를 자동으로 측정하여 트레이닝 데이터 세트를 획득하였다. 연료량을 추정하는 연료량 측정 소프트웨어를 트레이닝 데이터 세트와 함께 삼선형보간법을 사용하여 개발하였다. 개발된 연료량측정시스템은 참값을 알고 있는 테스트 데이터 세트의 연료 추정 오차를 측정하여 검증하였다. 테스트를 통해 개발된 연료량측정시스템의 오차가 TSO-C55 문서의 기준을 충족하는 것을 확인하였다.

• 제어로봇시스템학회논문지
• /
• 제7권8호
• /
• pp.680-688
• /
• 2001

In this paper, the fuzzy control with variable input gain is applied to maintain the consistent tension in the process of taking up and releasing texture. In the process of discharging web on one side rolling it on another, the take-up drum gets smaller on the release drum side as it gets bigger on the rolling side, thus it is necessary to change the balance of velocity between the sides. In order to solve the problem a tension controller is necessary. The PI control method has been employed to maintain the consistent tension, but the PI control method produces a problem which requires an experienced worker with the traits of the machine, in order to perform the fine adjustments according to the environment of the process. For solving the above problem, we apply fuzzy control to the tension system, in order to produce a uniform roll. For the performance test, the fuzzy controller does not need to revise the parameters. Therefore the fuzzy controller exhibits an excellent additivity for the tension system where the system is changed with time.