• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.42-45
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• 2007

Recrystallization behavior during ingot-breakdown process of Alloy 718 was investigated with finite element analysis and experimental approaches. In order to analyze microstructural changes during the cogging process of an Alloy 718 ingot, the side-pressing and heat treatment tests were performed at different temperatures and ram speed. From the side-pressing and heat treatment test results, it was found that microstructural changes during hot forging of Alloy 718 ingot greatly influenced on a close interaction between dynamic and static-recrystallization behaviors. A recrystallization model of Alloy 718 was used to predict the complex microstructural variation during continuous heating and forging processes of the cogging, and the predicted grain size and its distribution were compared with the actual cogged Alloy 718 billet.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.741-743
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• 2000

In this paper the relationship between the pressing force applied to rotors and the characteristics of ultrasonic motor are discussed. The characteristics of ultrasonic motor using a piezoelectric vibrator were systematically studied. And these were applied to the construction of a card forwarding device. The principle of ultrasonic motor is to use an elliptical motion generated on the side of the vibrator, and the elliptical motion of the ultrasonic motor was obtained by complex oscillation of $L_1-B_4$ mode. As the experimental results. the forwarding speed of the card increased linearly as the pressing force applied to rotors increased. The forwarding speed of the card was 16.0 cm/s when the pressing force applied to rotors was 1 N. The forwarding force of the card increased linearly as the pressing force applied to rotors increased. The forwarding force of the card was 398 mN when the pressing force applied to rotors was 1 N. Therefore, this ultrasonic motor can be expected to be used for card-forwarding device and so on.

• 소성∙가공
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• 제4권3호
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• pp.267-281
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• 1995

Preform design is one of the critical fields in metal forming. The finite element method(FEM) has been effective in designing preforms and process sequence, for which the backward tracing scheme of the rigid-plastic FEM has been explored. In this work a program using the backward tracing scheme by the rigid-plastic FEM is developed for three-dimensional plastic deformation, which is an extension of the scheme from two-dimensional cases. The calculation of friction between workpiece and die, and handling of boundary conditions during backward tracing require sophisticated treatment. The developed program is applied to upsetting of a rectangular block and to side pressing of a cylindrical workpiece. The results of the two applications show feasibility of the program on three-dimensional plastic deformation.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.433-435
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• 2005

We have studied the realigning behavior of liquid crystal molecules in liquid crystalline polymer/liquid crystal(LCP/LC) system when they are exposed to external stimulation such as bending and pressing. The birefringence of the LCP/LC in a flexible display device was measured as a function of bending or pressing deformation. The microscopic dynamic behavior of main chain, side chain, and the LC were characterized by FTIR and polarization optical microscopy. When the device is deformed in scattering memory state, liquid crystal(LC) director is found to align from randomly oriented domain state(scattering state) to homeotropic state.

• 대한기계학회논문집A
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• 제27권9호
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• pp.1539-1545
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• 2003

A lot of researches have been performed on the equal channel angular pressing (ECAP) which produces ultra-fine grains. Along with the experiments, the finite element method has been widely employed to investigate the deformation behavior of specimen during ECAP and the effects of process parameters of ECAP. In this paper, pure-Zirconium is considered for ECAP process by using three-dimensional finite element analysis. The results have been compared with those of previous two-dimensional analysis and with the experimental results

• 소성∙가공
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• 제20권2호
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• pp.110-117
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• 2011

The purpose of this work is to develop of a press forming process for mobile phone battery cover as an alternative to the current manufacturing process by laser welding. This press forming process consists of a combination of bending, side pressing and side bending operations. The dimensional error for each process was investigated by finite element(FE) analysis and the Taguchi optimization method. The spreading of the cover width in the side pressing process was adjusted by modifying the blank shape with a notch. The over-bending method was adopted to compensate the spring-back which occurs after bending. Forming experiments were performed to verify the reliability of the developed press forming process. In addition, the strength of the product was evaluated to verify the suitability of the battery cover manufactured with this new press forming process. The results of the forming experiments indicate that the dimensional accuracy of the battery cover is within the required tolerance. The strength of the battery cover was evaluated to 547N which is larger than required strength of 400N.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.69-74
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• 2008

The heat generated by the brake system of vehicles results in reduction of friction force on the brake surface and vibration during a braking. To solve these problems, extensive research for the brake shape has been conducted such as drilling cooling holes on the brake disc, accommodating ventilated holes and etc. In this study, we suggest the circumferential pressing type brake disc in order to improve its cooling performance. In order to compare the cooling-down efficiency between the conventional side-pressing type and the circumferential-pressing type, we adopted the FMVSS 105-77 as thermal analysis conditions and This newly proposed concept has been verified using Thermal-structure Coupled Field Analysis along with comparative analysis with the existing ventilated disk.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.661-665
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• 2002

A lot of investigations have been made in recent years on the equal channel angular pressing (ECAP) which produces ultra-fine grains. The finite element method has been used to investigate this issue. In this paper, pure-Zirconium is considered far ECAP process by three dimensional finite element analysis. The effects of fiction on the deformation behavior have been investigated and compared with two dimensional finite element analysis.

• 동국한의학연구소논문집
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• 제8권2호
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• pp.155-173
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• 2000

한의학의 진단(診斷)에는 망(望) 문(聞) 문(問) 절(切)의 사진법(四診法)과 여러 가지의 변증체계(辨證體系), 즉 기혈진액변증(氣血津液辨證) 장부변증(臟腑辨證), 육경변증(六經辨證), 위기영혈변증(衛氣營血辨證), 삼초변증(三焦辨證), 사상체질변증(四象體質辨證) 등이 응용되어 지고 있으며, 또한 그와 더불어 병상(症狀) 증후감병진단법(證候鑑別診斷法)등이 선택적으로 활용되어 지고 있다. 이러한 광범위(廣範位)한 진단방법(診斷方法)가운데 절진(切診)은 손가락 및 손바닥의 감각(感覺)을 운용(運用)해서 일정부위(一定部位)를 촉지(觸指), 접압(接壓)하는 검사방법(檢査方法)으로써 절맥진(切脈診)과 접진(接診)으로 크게 나눌 수 있다. 이중 안진(按診)이란 손을 사용하여 직접 환부에 촉모(觸摸) 안압(按壓)하여 이상변화를 알아내고 나아가서는 질병(疾病)의 부위(部位)와 성질(性質)과 병정(病情)의 경중(輕重) 등의 내부(內部)의 변화(變化)와 체표(體表)의 반응(反應)을 관찰(觀察)하여 중요(重要)한 변증자료(辨證資料)를 얻는 진단방법(診斷方法)의 한 종류(種類)를 말한다. 또한 접진(接診)에는 안기표(按肌表), 접수족(接手足), 안흉복(按胸腹), 접유혈진법(接兪穴診法)등을 들 수 있다. 배유혈(背兪穴)의 진단법(診斷法)은 경기(經綺)이라는 반응로(反應路)를 통(通)하여 체표(體表)에 발현(發現)되는 압통(壓痛), 자발통(自發痛), 긴장(緊張), 이완(弛緩), 경결(硬結) 및 조색상물(條索狀物) 등의 현상(現象)으로 부터 내부장기(內部臟器)의 병변(病變)을 진단(診斷)하는 방법(方法)이다. 이에 저자(著者)는 접진(接診)의 내용(內容)과 방법(方法)을 연구하면서 십이경맥(十二經脈)의 시동병(始動病) 소생병(所生病)을 알아보고 혈위진단(穴位診斷)의 방법(方法) 및 주의점(注意點)등을 아울러 정리하므로써 다음과 같은 결론(結論)을 얻었다. 1. 유혈(兪穴)은 각(各) 장부(臟腑)의 사기(邪氣)가 주입(注入)하는 곳으로 장병(臟病) 한증(寒症) 허증(虛症)의 의미를 내포한 음성병증(陰性病症) 치료(治療)에 중요(重要)한 곳이다. 2. 유차(兪次)의 촉진(觸診) 즉(卽) 모지(母指)로서 척추극돌기(脊椎棘突起) 좌우측(左右側)을 접압(接壓)하여서 상향(上向)이나 하향(下向)으로 추압지(推壓指)하면 극돌기(棘突起)의 돌(突), 함요(陷凹), 긴장(緊張), 이완(弛緩) 및 압통(壓痛)의 출현부위(出現部位)에 따라 계통별(系統別) 질환(疾患)을 판단(判斷)할 수 있다. 3. 실제(實際) 임상(臨床)에서 환자(患者)의 진단(診斷) 치료(治療)에 있어서 배부접진(背部接診)은 중요(重要)한 진단(診斷)의 한 영역(領域)으로 빠뜨리지 말고 꼭 참고(參考)하여야 할 것으로 사료(思料)된다. 4. 장부질환(臟腑疾患)에 대한 진단방법(診斷方法)의 다양화(多樣化)와 치료영역(治療領域)의 확대(擴大) 및 치료율(治療率)의 상승(上昇)을 위해 배부유혈(背部兪穴)의 정확(正確)한 인식(認識)과 유혈접진(兪穴接診)을 통하여 정확(正確)한 진단(診斷)이 되었으면 한다.

• 한국초전도ㆍ저온공학회논문지
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• 제19권3호
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• pp.27-32
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• 2017

The effects of artificial holes on the trapped magnetic fields and magnetic levitation forces of very large single-grain $Y_{1.5}Ba_2Cu_3O_{7-y}$ (Y1.5) bulk superconductors were studied. Artificial holes were made for Y1.5 powder compacts by die pressing using cylindrical dies with a diameter of 30 mm or 40 m, or rectangular dies with a side length of 50 mm. The single grain Y1.5 bulk superconductors (25 mm, 33 mm in diameter and 42 mm in side length) with artificial holes were fabricated using a top-seeded melt growth (TSMG) process for the die-pressed Y1.5 powder compacts. The magnetic levitation forces at 77 K of the 25 mm single grain Y1.5 samples with one (diameters of 4.2 mm) or six artificial holes (diameters of 2.5 mm) were 10-17% higher than that of the Y1.5 sample without artificial holes. The trapped magnetic fields at 77 K of the Y1.5 samples with artificial holes were also 9.6-18% higher than that of the Y1.5 sample without artificial holes. The 33 mm and 42 mm single grain Y1.5 samples with artificial holes (2.5 mm and 4.2 mm in diameter) also showed trapped magnetic fields 10-13% higher than that of the Y1.5 samples without artificial holes in spite of the reduced superconducting volume fraction due to the presence of artificial holes. The property enhancement in the large single grain Y1.5 bulk superconductors appears to be attributed to the formation of the pore-free regions near the artificial holes and the homogeneous oxygen distribution in the large Y123 grains.