• Design & Manufacturing
• /
• 제12권2호
• /
• pp.34-39
• /
• 2018

The biggest topics in the automobile industry are light weightening and fuel efficiency improvement. There's a lot of research going on. It is focused on light weight materials. Light weight material is seen as the best way to reduce fuel consumption and to solve the problem of environmental pollution and resource depletion. For the light weight materials, new materials such as aluminum, magnesium, and carbon-hardening materials can be found. Research on the joining techniques of dual materials, improvement of material properties by improving the method of manufacture of existing materials, and studies on ultra-high strength steel sheets are expected to take up the most weight in lightweight materials. As the strength of the ultra-high strength steel sheets increases during forming, it is difficult to obtain dimensional precision due to the increase in elastic restoring force compared to mild or high strength steel sheets. Spring back is known to be affected by a number of factors due to poor plastic molding, and can be divided into the effects of the material spraying and the process. The study on the plasticitic variables were studied as plasticitic factors that can be controlled by a part company. Tensile testing of ultra-high strength materials was conducted to derive properties for plasticitic analysis and to analyze spring back with two factors controlling the height of the bead and blank holding force by adding tensile force and controlling the flow rate.

• 한국강구조학회 논문집
• /
• 제20권6호
• /
• pp.711-722
• /
• 2008

기존 콘크리트충전 각형강관(CFT) 구조에 사용하는 각형강관은 4개의 판을 용접하여 제작하는 박스칼럼이 일반적이다. 그러나 이러한 강관은 제작효율이 저하되며, 또한 기둥-보 접합부에는 내측 다이아프램과 관통 다이아프램을 용접하는데 특수한 용접기술이 필요하다. 따라서, 얇은 강판을 절곡하는 방식으로 응력집중 위치의 용접을 피하고, 단면효율이 극대화된 내부앵커 돌출형의 각형강관을 개발하게 되었다. 본 연구에서는 이 개발된 강관의 기둥-보 접합부로 외다이아프램형식을 채택하고. 보 플랜지의 응력 전달을 명확히 하기 위한 기둥-보 접합부 상세를 확 정하고자 이 접합부에 대한 단순인장 실험체를 제작하여 성능평가 실험을 수행하였다. 이 실험을 통해 콘크리트충전 기둥-보 접합부의 기둥-보 플랜지 용접 유무, 기둥-다이아프램 용접량, 콘크리트 충전유무, 다이아프램 설치 기둥과 일반기둥의 비교 등에 따른 인장영역 응력분포 및 내력평가를 진행하고 내부 앵커와 콘크리트 사이의 합성효과를 파악하였다.

• 한국산학기술학회논문지
• /
• 제15권2호
• /
• pp.666-671
• /
• 2014

최근 디젤 차량과 같은 내연기관의 고효율화에 따라, 보조난방 열원으로서 PTC 히터의 사용이 증가하는 추세이다. 디젤 차량의 시동 초기에는 냉각수의 온도가 난방으로 직접 사용하기에 충분히 높지 않으므로, 동절기 난방을 위해 보조난방 열원은 필수적이다. 본 연구에서는 스크린 인쇄 전극공정을 바탕으로 한 PTC 소자를 제작하였고, 이를 활용한 PTC 소자 모듈 및 히터를 설계 및 제작하였다. PTC 소자 모듈의 방열핀 접촉형상 및 전열소자의 크기 변경에 따른 난방성능 변화를 열유동 해석을 통해 분석하였고, 난방성능 실험을 수행하여 PTC 히터의 난방성능 및 효율 특성을 살펴보았다. PTC 히터 시작품의 경우, 기존 PTC 히터와 동등한 수준 이상의 난방성능 및 효율을 나타내었으며, 향후 이를 바탕으로 PTC 소자와 히터에 대한 공정개선 및 성능증대 연구를 수행할 계획이다.

• 대한비뇨기종양학회지
• /
• 제15권3호
• /
• pp.178-186
• /
• 2017

Purpose: Poloxamer 407 (P407) thermo-sensitive hydrogel formulations were developed to enhance the retention time in the urinary bladder after intravesical instillation. Materials and Methods: P407 hydrogels (P407Gels) containing 0.2 w/w% fluorescein isothiocyanate dextran (FD, MW 4 kDa) as a fluorescent probe were prepared by the cold method with different concentrations of the polymer (20, 25, and 30 w/w%). The gel-forming capacities were characterized in terms of gelation temperature (G-Temp), gelation time (G-Time), and gel duration (G-Dur). Homogenous dispersion of the probe throughout the hydrogel was observed by using fluorescence microscopy. The in vitro bladder simulation model was established to evaluate the retention and drug release properties. P407Gels in the solution state were administered to nude mice via urinary instillation, and the in vivo retention behavior of P407Gels was visualized by using an in vivo imaging system (IVIS). Results: P407Gels showed a thermo-reversible phase transition at $4^{\circ}C$ (refrigerated; sol) and $37^{\circ}C$ (body temperature; gel). The G-Temp, G-Time, and G-Dur of FD-free P407Gels were approximately $10^{\circ}C-20^{\circ}C$, 12-30 seconds, and 12-35 hours, respectively, and were not altered by the addition of FD. Fluorescence imaging showed that FD was spread homogenously in the gelled P407 solution. In a bladder simulation model, even after repeated periodic filling-emptying cycles, the hydrogel formulation displayed excellent retention with continuous release of the probe over 8 hours. The FD release from P407Gels and the erosion of the gel, both of which followed zero-order kinetics, had a linear relationship ($r^2=0.988$). IVIS demonstrated that the intravesical retention time of P407Gels was over 4 hours, which was longer than that of the FD solution (<1 hour), even though periodic urination occurred in the mice. Conclusions: FD release from P407Gels was erosion-controlled. P407Gels represent a promising system to enhance intravesical retention with extended drug delivery.

• 핵의학기술
• /
• 제18권1호
• /
• pp.49-61
• /
• 2014

인구의 고령화와 함께 골다공증성 척추압박골절 환자의 발병률은 매년 증가하는 추세이며 경피적 척추성형(percutaneous vertebroplasty, PVP)은 가장 많이 시행되는 표준화된 치료 방법이다. 시술 전 후의 정확한 진단평가에 있어 SPECT/CT 검사의 유용성이 우수하다는 연구 보고가 있으나 시술에 사용되는 골 시멘트(bone cement) 물질은 CT 영상에서 인공물(artifact)을 생성하여 영상품질에 영향을 미친다. 이에 본 연구에서는 골 시멘트가 SPECT/CT 영상에 미치는 영향을 평가하는 데 목적을 두었다. NEMA-1994 팬텀(phantom)에 배후방사능(3.6 kBq/ml), 열소(29.6 kBq/ml), 냉소(물)를 설정한 후 각 원통(cylinder)에 모형 시멘트를 삽입하여 영상 획득하였다. Astonish (Iterative: 4, Subset: 16)으로 재구성하였고, CT 보정 방법은 비감쇠보정(NAC), 감쇠보정(AC+SC-), 감쇠 및 산란보정(AC+SC+) 3가지 방법을 사용하였다. 각각의 보정방법에 따른 평균계수와 시멘트물질의 유 무에 따른 계수 변화율을 비교하고 대조도 회복 계수(contrast recovery coefficient, CRC)를 구했다. 또한, 압박골절 진단을 받은 환자 107명 중 PVP를 시행한 20명을 선별하여 추체를 골절, 정상, 시멘트로 나누고 연조직(척추기립근)을 포함 4곳의 평균 계수를 측정한 후, 뼈/연조직 간 계수 비(bone/soft tissue ratio, B/S ratio)을 구했다. NAC를 기준으로 AC+SC-, AC+SC+의 평균계수는 증가하였고, AC+SC-의 평균계수가 가장 높았으며, AC+SC+는 AC+SC-에 비해 상대적으로 낮았다. 시멘트 물질의 유 무에 따른 평균계수는 시멘트가 존재할 때 NAC, AC+SC-, AC+SC+에 따라 팬텀의 열소에서 12.4%, 6.5%, 1.5%, 냉소 75.2%, 85.4%, 102.9%, 배후방사능 13.6%, 18.2%, 9.1%, 임상영상의 골절부에서 33.1%, 41.4%, 63.5%, 정상부 53.1%, 61.6%, 67.7%, 연조직 10.0%, 4.7%, 3.6%의 증가율을 보였다. 반면 원통 내부의 시멘트 인접부에서 상대적 계수감소를 확인할 수 있었고, 병소에 대한 팬텀영상과 임상영상간의 계수 증가율은 상반된 양상을 보였다. 대조도 비를 나타내는 CRC와 B/S ratio는 NAC, AC+SC-, AC+SC+순으로 향상되었고, 팬텀의 냉소에서는 큰 변화 없이 일정하였다. 정량적 계수는 AC+SC-가, 대조도 비는 AC+SC+가 가장 높게 분석되었다. PVP 시행 환자의 척추 뼈 SPECT/CT 검사에서 AC+SC- 의 사용은 영상계수를 대폭 향상시켜 특히 병소의 농도가 높은 영상을 얻는 반면에 골 시멘트의 영향과 함께, 연부조직 및 산란영역의 영상잡음 계수까지 증가시키므로 대조도비를 향상시키는 AC+SC+의 적용을 병행한다면 임상진단에 유용할 것으로 사료된다.

• 동서간호학연구지
• /
• 제2권1호
• /
• pp.96-106
• /
• 1997

In Chinese medicine, the activities of removing and solving the inner cause are called the regimen in preventing the disease and the good condition of mind emphasizes us to practice ourselves the doctrine of regimen of the mind to promote the health and long life of the living body, in other words, it means we should have clean mind, less desire, less thought, less agony and widely open our emotion and will, and it also means the raising of good nature, the moral cultivation, and we can be healthy when we live by good virtus as the root of regiem. The meaning of the Qi has been expanded more and more since its origination throught the process of practice and perception of man. 1) Matter is changed to the smoke when burned, the energy of water becomes the rain in the sky and the rain raises all living creatures by making them wet. Throught these changes of circulation, men could realize the energy to be the common and original matter of forming all the creatures. 2) The direction of showing the breathing of men in and out has been expended. 3) It was widely understood as the meaning of showing vitality of men, and it was the original root of chinese medicine. 4) It was expended to be showing spirit of nature such as the sun, moon, star, sky, land, mountain and the moral spirit of men as peacefullness. By the original meaning of the word of energy expanded to the wider side of sky, land, men and things, nature, society, man and the moral spirit could get the unified basis of the matter. As the above, the word of Qi has been used in wider meaning at this time from the past. In other words, all things in the universe come into being and extinct by the chang of motion of the Qi and it is recognized to be the living activity in human body. The Qi-kong based on this energy and the motion applied to our daily life are very extensive (Lee, Hye - lung, 1997). Here are the summaries of the effect of the Qi-kong ; 1) The physical constitution is strenthened, physiological function is prosperous and we are free from various geriatric disease and psychosomatic disease not to mention the cold and indigestion. 2) It maintains the clear spirit, elevates intelligence, strengthens the spiritual power and demonstrates the potentiality at the amximum. 3) It maintain beautiful figure and clean skin never losing the charm but full of energy and vitality. 4) It keeps the balanced body never suffering from the unbalance of the bones, various and neuralgia. 5) It maintain the spiritual comfort, the natural posture in everything and real happiness (Lee, Hye-Jung, 1997 : Suh, Yong Kyu, 1989). Chinese medicine mentions the motion by Qi with Qi - kong. But the motion does not require special method in Western medicine. I t is the only way of living of our ancestor indaily life. It is maintaining the healthy lifr by training the Qi, and it is the motion of being with the nature with the open mind in breathing rather than artificially restricting our daily life, it is the motion of the body.