Microstructure and High Temperature Mechanical Property of Fe–Cr–B Based Metal/Ceramic Composite Manufactured by Metal Injection Molding Process

Kee‑Ahn Lee,Jin‑Han Gwon,윤태식 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.2

This study investigated the microstructure and the room and high temperature mechanical properties of Fe–Cr–B alloy manufacturedby metal injection molding. In addition, hot isostatic pressing was performed to increase the density of the material,and a comparison of properties was made. Microstructural observation confirmed a bi-continuous structure composedof a three-dimensional network of α-Fe phase and (Cr,Fe)2B phase. The HIPed specimen featured a well-formed adhesionbetween the α-Fe phase and boride, and the number of fine pores was significantly reduced. The tensile results confirmed thatthe HIPed specimen (RT to 900 °C) had higher strengths compared to the as-sintered specimen, and the change of elongationstarting from 700 °C was significantly greater in the HIPed specimen. Fractography suggested that cracks propagatedmostly along the interface between the α-Fe matrix and boride in the as-sintered specimen, while direct fracture of boridewas observed in addition to interface separation in the HIPed specimen.

외상성 횡격막 손상

안성국,이상목,이기형,고석환,김용호,박호철,고영관,조규석 대한응급의학회 1995 대한응급의학회지 Vol.6 No.1

Fifty two cases of traumatic diaphragmatic injuries that we have experienced from Jan. 1973 to Oct. 1994 were evaluated. The following results were obtained. The age of the patient was ranged from 1 to 74 years. Male was 38 and female was 14 in number with a ratio of 2.7 : 1. The traumatic diaphragmatic injuries were due to blunt trauma in 35 cases(motor vehicle accident 25, fall down 8, press 1, kick by fight 1) and penetrating trauma in 17 cases(stab wound 15, shot wound 1, explosion 1). In the blunt trauma, the preoperative diagnosis of the diaphragmatic injury was possible in 25 out of 35 cases(71%) and in the penetrating trauma, 15 out of 17 cases(88%). In the blunt trauma, the repture site was located in the left in 22 cases(63%) and in the right in 13 cases(31%). In the penetrating trauma, the rupture site was located in the left in 9 cases(53%) and in the right in 8 cases(47%). In the blunt trauma, 20 cases(63%) were treated within 24 hours and in the penetrating, 15 cases(88%) within 24 hours. In the blunt trauma, the herniated organs into the thorax were stomach(7), omentum(6), spleen(6), liver(5), colon(4), small bowel(2) and in the penetrating, stomach(7), colon(6), omentum(3), liver(2), and spleen(1) were herniated. Injury severity score(ISS) of 35-blunt trauma ranged from 11 to 66 with mean value of 30.6. Mean ISS of survivors and nonsurvivors was 27.6 and 52.7 respectively. The diaphragmatic repair of 49 cases was performed with thoracic approach in 23 cases, thoracoabdominal approach in 7 cases and abdominal approach in 19 cases, and 3 cases were not operated. The postoperative complication and mortality were developed in 16 out of 49 cases(33%) and in 5 cases(9.6%) respectively, and the causes of death were hypovolemic shock(1), combined head injury(2), asphyxia(1), and pulomnary edema and renal failure(1). In conclusion, the injuries of the diaphragm should be suspected in all patients with severe blunt trauma or penetrating injuries at thorax and upper abdominal area near the diaphragm. All of the cases had associated injury and most of deaths were related to the severity of associated injuries.

β-CuZn 합금의 항복강도 이상거동에 미치는 변형률 속도와 온도의 영향

이기안,장영원,이종수 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.3

A series of tensile and load relaxation behaviors in B2 type β-CuZn alloy have been examined to clarify the strain rate & the temperature dependence of yield stress anomaly. It has been found in tensile tests that the region showing anomalous peak of yield stress moves to a higher stress and higher temperature region with increasing strain rate. The anomalous yielding region below peak temperature(T_p) revealed slightly positive strain rate dependence, while the region above T_p showed considerably positive strain rate dependence. The slip lines formed below peak temperatures (T_P) were clearly visible with naked eye(coarse slip lines), and became finer near T_p(fine slip lines), while they disappeared completely above T_p. Based on the different tendency of temperature and strain rate dependence of anomalous yielding as the above-mentioned results, two types of deformation modes were suggested and incorporated into the flow curve analysis, which was in accord well with the experimental results. The slightly positive strain rate dependence of yield stress anomaly indicated that the yield stress anomaly in β-CuZn alloy mainly seemed to be attributed to the vacancy hardening.

Fe-29%Ni-17%Co 코바 합금의 고온 내산화성 및 열간 가공성에 미치는 Mo 첨가의 영향

이기안,조창완,성병근,김병문,김문철 대한금속ᆞ재료학회 2006 대한금속·재료학회지 Vol.44 No.3

甲狀腺 홀몬의 受容體에 關한 硏究

李民化,安鳳煥,李起榮,朴鐘一 全南大醫大 1980 전남의대학술지 Vol.17 No.1

질화 분위기에서 결정화 된 Fe_(73.5)Si_(13.5)B_(9)Cu₁Nb₃ 연자성 합금의 자기적 성질

이기선,박인수,이기안,김문철,장석훈 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.11

Amorphous Fe_(73.5)Si_(13.5)B_(9)Cu₁Nb₃ alloy was crystallized in nitriding atmosphere of mixture gas of NH₃ and hydrogen. The crystallization at 823K showed the high electrical resistivity ranging from 494 to 538 mW-cm, which was higher level compared with nano-crystalline Fe_(73.5)Si_(13.5)B_(9)Cu₁Nb₃ alloy with a resistivity of about 110 mW-cm. Through the nitridation treatments, the amorphous alloy was transformed into nano-sized crystalline Fe3Si including iron nitrides such as γ' -Fe₄N phases. EPMA-concentration depth profiles confirmed an existence of nitrogen-rich region on the surface of the alloy ribbon, leading to the preferential formation of g -Fe4N phase. The formation of γ' -Fe₄N phase leaded to an increase of the resistivity and provided stable permeability and a low core loss at high frequency.

고속핵에서 GABA가 동맥압에 미치는 영향

이정헌,오기화,안동국,박재식 慶北大學校 醫科大學 1996 慶北醫大誌 Vol.37 No.3

목적 : NTS (nucleus tractus solitarius)는 압감수성 반사 구심성 신경이 처음 시냅스를 형성하는 곳으로 동맥압 조절에 중요한 역할을 한다. NTS에서 어떤 특정 물질이 동맥압 조절에 관여하는지는 정확히 밝혀지지는 않았지만, NTS에 존재하는 많은 물질들이 이들 과정에 관여하고 있다. 그중 하나인 GABA성 약물이 NTS에서 순환계에 미치는 영향을 구명하고자 본 실험을 시행하였으며 아울러 반대편 NTS를 lidocaine으로 억제하였을 경우의 변화를 관찰하여 NTS에서 신경회로 일단을 밝히고자 하였다. 대상 및 방법 : 실험동물은 체중 300-500g 되는 숫컷 Wistar쥐를 사용하였다. 동맥압 측정과 약물 주입을 위하여 대퇴 동정맥에 삽관하였다. 이어서 기관지절개술을 시행하였으며 체온을 36-37℃ 되게 열판을 이용하여 조절하였다. 쥐를 뇌 정위 고정 장치에 두고 머리를 45°숙여 NTS를 노출시킨 다음 약물을 10초간에 걸쳐 80nl주입하였다. 결과 : 인공 뇌척수액을 주입하면 동맥압의 변화가 거의 없었으나 동량의 GABA를 NTS에 주입하면 동맥압이 증가하였다. GABA에 의해 동맥압이 증가된 상태에서 반대측 NTS에 lidocaine을 주입하여 한쪽 기능을 억제시키면 동맥압이 더욱 증가하였다. 또한 lidocaine주입 후 반대쪽의 건전한 NTS에 GABA를 재차 주입하면 동맥압 증가가 적었다. 그리고 GABA를 NTS에 주입 후 정맥으로 nitroprusside를 주입하면 GABA 주입이 없는 대조군에 비해 동맥압 감소가 더 컸으며, lidocaine으로 마취하여 한쪽 NTS의 기능을 차단한 후 반대쪽 건전한 NTS에 GABA를 주입한 경우는 동맥압 감소가 적었다. 동일한 방법으로 lidocaine을 주입한 후 phenylephrine으로 승압을 시키면 동맥압 증가가 적었다. 압감수성 반사는 NTS에 GABA를 주입하거나 또는 반대편 NTS를 lidocaine으로 마취하여 기능을 억제시킨 경우에 둔화되었다. 결론: NTS에서 GABA가 동맥압의 조절 인자로 작용하며, 양쪽 NTS는 상호작용하고 있는 것으로 보인다. The nucleus tractus solitarius (NTS), the site of termination within the brain of baroreceptor afferent fibers, has been shown to be involved in the regulation of arterial pressure (AP). Many neuroactive substances present within the NTS have been shown to be involved in this process, although the manner in which any specific neurotransmitter acts physiologically in the regulation of AP has not been completely elucidated. The present study was intended to clarify the mechanism of action of GABA in the NTS and also to examine the cardiovascular response to inhibition of the contralateral NTS by lidocaine. Male Wistar rats weighing 300-500 g were employed for the experiment. The femoral artery and vein were cannulated to record the arterial pressure (AP) and to inject nitroprusside or phenylephrine, respectively. The tracheotomy was performed and body temperature was kept to 36-37℃. Rats were mounted in a stereotaxic frame with the head flexed downward to an angle of 45°. After the NTS was exposed. GABA or lidocaine was microinjected into the NTS in a volume of 80 nl over 10 seconds through a glass micropipette (outer diameter of the tip 50 ㎛) connected to a 1 ㎕ Hamilton microsyringe. The results obtained are summarized as follows. Microinjection of artificial CSF into the ipsilateral NTS did not alter basal AP. In contrast, microinjection of the same volume of GABA into the NTS produced a significant increase in the AP. The results presented thus far indicated that the volume injected did not affect AP. In animals with elevated AP by GABA injection, injection-of lidocaine into the contralateral NTS resulted in a further increase in AP. After the contralateral NTS was inhibited with lidocaine. injection of GABA into the NTS produced a less increase in AP. After microinjection of GABA into the NTS, the nitroprusside administered i.v. accentuated the increase of AP but not after microinjection of lidocaine into the contralateral NTS. Similar results were obtained with i.v. injection of phenylephrine after pretreatment of lidocaine into the NTS. The baroreflex sensitivity was reduced by microinjection of GABA into the NTS or microinjection of lidocaine into the contralateral NTS. These results suggest that alterations in GABA-mediated neural transmission in the NTS contribute to the regulation of AP and the NTS of both sides have a mutual interaction.

한국산 바질(Ocimum basilicum L.)의 휘발성 성분

이재곤,안대진,곽재진,장희진,정기택,이종철 한국식품영양학회 1999 韓國食品營養學會誌 Vol.12 No.5

동시증류추출장치를 사용하여 분리한 Sweet계 바질(Ocimum basilicum)의 4개 품종(anise, darkopal, lettuce, sweet)의 휘발성 성분을 GC/MSD로 확인하였다 확인된 성분을 기능기별로 분류하면 alcohol 성분들이 11종, carbonyl 화합물이 6종, terpene 관련 화합물이 19종. ester 화합물이 5종으로 나타났다. 주요 화합물들은 1,8-cineole(2.86∼5.04%), camphor(1.07∼l.87%), α-Bergamotene(2.05∼5.40%), methyl chavicol(0∼25.49%), eugenol (3.55∼13.53%) 등의 carbonyl 화합물과 linalool(28.52∼36.50%), bornyl acetate(0.48∼2.79%), methyl cinnamate(0∼23.12%)등의 alcohol과 ester류, cis-ocimene(1.15∼2.02%), β -cubebene(2.77∼4.80%), cadinene(1.08∼1.70%)등의 terpene 화합물이 주요 성분으로 확인되었다. Darkopal, lettuce, sweet 바질은 linalool(30.09∼35.50%), methyl chavicol(8.09∼25.49%)이 주요 성분으로 나타났고, Anise 바질은 linalool(28.52%), methyl cinnamate(23.12%)가 주요 성분으로 확인되었으나 바질의 주요성분으로 알려져 있는 methyl chavicol은 검출되지 않았다. The essential oils of anise, darkopal, lettuce and sweet basils cultivated in Korea were extracted by simultaneous steam distillation and extraction method and were analyzed by GC/MSD. Total 41 components were identified in essential oils including 11 alcohols, 6 carbonyls, 19 hydrocarbons and 5 esters components. The major components were 1,8-cineole, linalool, α-bergamotene, β-elemene, methyl chavicol, β-cubebene, methyl cinnamate and eugenol. Darkopal, lettuce and sweet basils were rich in linalool(30. 1∼36.5%), methyl chavicol(8.1∼25.5%) and relatively poor in methyl cinnamate(0∼2.71%). Anise basil was rich in linalool(28.5%) and methyl cinnamate(23.1%). However, methyl chavicol, which was known as one of the main components of basil, was not detected.

Fe-Ni-Co 저열팽창성 합금의 고온 변형 특성 및 열간가공에 따른 열팽창 거동 연구

이기안,박종혁,조봉현,남궁정,김문철 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9

The high temperature deformation behavior and the effect of hot compression on the thermal expansion behavior of Fe-29Ni-17Co low thermal expansion Kovar alloy were investigated in the compressive temperature range of 900~1300℃ at the strain rate range of 25~0.01 sec.^(-1). The temperature (T) and strain rate (ε˙) dependence of the flow stress (σ_(0.7)) could be well described by hyperbolic sine law as ε˙= A [sinh(0.0084 σ)^(5.2018)] exp(-330.41/RT). Surface hot cracking and significant voids around grain boundary could be found at low temperature below 1000℃ and low strain rate (0.01 sec.^(-1)). Thermal expansion coefficient α_(30~400) generally increased with increasing compressive temperature. Moreover, α_(30~400) remarkably increased as strain rate decreased at high temperature above 1100℃. However the thermal expansion coefficient α_(30~400) of low compressive temperatures (900℃ and 1000℃) anomalously increased especially at high strain rates. Experimental results indicated that not only α phase appearance but also grain size had definite influence on the thermal expansion behavior with hot deformation. The correlation between microstructure and thermal expansion behavior of Kovar alloy were also discussed.

非特異性 PHOSPHATASE에 關한 硏究 : 사람 胎盤 Alkaline Phosphatase의 燐蛋白 燐酸水解活性에 關하여

李民化,安鳳煥,李起榮,曺仲東 全南大醫大 1980 전남의대학술지 Vol.17 No.2