Selective Laser Sintering of Co-Cr Alloy Powders and Sintered Products Properties

이동완,Thuyet-Nguyen Minh,김진천 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.1

Metal-additive manufacturing techniques, such as selective laser sintering (SLS), are increasingly utilized for new biomaterials, such as cobalt-chrome (Co-Cr). In this study, Co-Cr gas-atomized powders are used as charge materials for the SLS process. The aim is to understand the consolidation of Co-Cr alloy powder and characterization of samples sintered using SLS under various conditions. The results clearly suggest that besides the matrix phase, the second phase, which is attributed to pores and oxidation particles, is observed in the sintered specimens. The as-built samples exhibit completely different microstructural features compared with the casting or wrought products reported in the literature. The microstructure reveals melt pools, which represent the characteristics of the scanning direction, in particular, or of the SLS conditions, in general. It also exposes extremely fine grain sizes inside the melt pools, resulting in an enhancement in the hardness of the as-built products. Thus, the hardness values of the samples prepared by SLS under all parameter conditions used in this study are evidently higher than those of the casting products.

Antimicrobial Cyclic Peptides for Plant Disease Control

이동완,김범석 한국식물병리학회 2015 Plant Pathology Journal Vol.31 No.1

Antimicrobial cyclic peptides derived from microbesbind stably with target sites, have a tolerance to hydrolysisby proteases, and a favorable degradability underfield conditions, which make them an attractive propositionfor use as agricultural fungicides. Antimicrobialcyclic peptides are classified according to the types ofbonds within the ring structure; homodetic, heterodetic,and complex cyclic peptides, which in turn reflectdiverse physicochemical features. Most antimicrobialcyclic peptides affect the integrity of the cell envelope. This is achieved through direct interaction with the cellmembrane or disturbance of the cell wall and membranecomponent biosynthesis such as chitin, glucan,and sphingolipid. These are specific and selective targetsproviding reliable activity and safety for non-targetorganisms. Synthetic cyclic peptides produced throughcombinatorial chemistry offer an alternative approachto develop antimicrobials for agricultural uses. Thosesynthesized so far have been studied for antibacterialactivity, however, the recent advancements in powerfultechnologies now promise to provide novel antimicrobialcyclic peptides that are yet to be discovered fromnatural resources.

반응표면분석법에 의한 머위 잎의 petasin 추출공정 최적화

이동완(Dong Wan Lee),이세열(Se Yeul Lee),정헌식(Hun Sik Chung),최영환(Young Whan Choi),임동순(Dong Soon Im),이영근(Young Guen Lee) 한국생명과학회 2013 생명과학회지 Vol.23 No.11

머위 잎에서 알레르기성 천식에 효과적 치료제로 알려져 있는 petasin을 효율적으로 추출하기 위해 반응표면분석법을 사용하여 petasin 추출공정 최적화를 실시하였다. Box-Behnken design에 따라 설정한 에탄올 농도(40-80%), 추출 rpm (125-225), 추출시간(1-3 hr)을 독립변수로 하고 추출물의 특성 즉, 추출수율과 petasin 함량을 종속변수로 하여 분석을 실시하였다. 추출물의 petasin 함량은 에탄올 농도, 추출 rpm, 추출시간의 유의적인 영향을 받으며 특히, 에탄올 농도의 영향이 크며 이의 수준이 높아짐에 따라 증가하는 것으로 나타났다. 추출조건에 따른 petasin의 거동은 유의적인 회귀식으로 설명이 가능한 것으로 확인되었다. 반응표면분석 결과, 머위 잎으로부터 petasin의 추출에 최적인 조건으로 에탄올 농도는 79.92%, 추출 rpm은 178.10, 추출시간은 2.06 hr로 각각 결정되었다. Petasin extracted from Petasites japonicus leaves has been well known to be effective in the treatment of allergic asthma. This study was carried out to optimize the extraction process of petasin from P. japonicus leaves by response surface methodology (RSM). The dried powder of P. japonicus leaves was extracted at ethanol concentrations ranging from 40% to 80%, extraction rpm ranging from 125 rpm to 225 rpm, and extraction time ranging from 1 to 3 hours. The effects of the extraction conditions on the dry yield and petasin content of the extracts were investigated using a second-order Box-Behnken design. The petasin content was significantly affected by ethanol concentration, extraction rpm, and extraction time, tending to increase more with increasing ethanol concentration. The optimum condition for petasin extraction from Petasites japonicus leaves was 79.92% in ethanol concentration, 178.10 rpm in extraction rpm, and 2.06 hours in extraction time, respectively.

Isolation and Genomic Characterization of the T4-Like Bacteriophage PM2 Infecting Pectobacterium carotovorum subsp. carotovorum

임정아,이동완,Sunggi Heu 한국식물병리학회 2015 Plant Pathology Journal Vol.31 No.1

In order to control Pectobacterium carotovorum subsp. carotovorum, a novel virulent bacteriophage PM2 wasisolated. Bacteriophage PM2 can infect 48% of P. carotovorumsubsp. carotovorum and 78% of P. carotovorumsubsp. brasilliensis but none of atrosepticum, betavasculorum,odoriferum and wasabiae isolates had beeninfected with PM2. PM2 phage belongs to the familyMyoviridae, and contains a large head and contractiletail. It has a 170,286 base pair genome that encodes291 open reading frames (ORFs) and 12 tRNAs. MostORFs in bacteriophage PM2 share a high level of homologywith T4-like phages including IME08, RB69,and JS98. Phylogenetic analysis based on the aminoacid sequence of terminase large subunits confirmedthat PM2 is classified as a T4-like phage. It contains nointegrase- or no repressor-coding genes related to thelysogenic cycle, and lifestyle prediction using PHACTsoftware suggested that PM2 is a virulent bacteriophage.

Powder Bed Fusion 공정으로 제조한 STS 316L의 미세조직과 후속 열처리 특성

송승윤,이동완,Dinh Van Cong,김진우,이성모,주승환,김진천 한국분말재료학회 2022 한국분말재료학회지 (KPMI) Vol.29 No.1

In the powder bed fusion (PBF) process, a 3D shape is formed by the continuous stacking of very fine powder layers using computer-aided design (CAD) modeling data, following which laser irradiation can be used to fuse the layers forming the desired product. In this method, the main process parameters for manufacturing the desired 3D products are laser power, laser speed, powder form, powder size, laminated thickness, and laser diameter. Stainless steel (STS) 316L exhibits excellent strength at high temperatures, and is also corrosion resistant. Due to this, it is widely used in various additive manufacturing processes, and in the production of corrosion-resistant components with complicated shapes. In this study, rectangular specimens have been manufactured using STS 316L powder via the PBF process. Further, the effect of heat treatment at 800 °C on the microstructure and hardness has been investigated.

연하 유발성 심방세동 1예

이현국,전국진,이동완,이혜정,김준홍,홍택종,신영우 대한내과학회 2005 대한내과학회지 Vol.69 No.5S

상부 위장관 내시경 검사의 전처치 약물에 대한 고찰

강영진,양웅석,송근암,이동완 대한소화기내시경학회 1988 Clinical Endoscopy Vol.8 No.1

In order to assess the effects of diazepam and meperidine as premedication for upper gastrointestinal endoscopy, eighty eight patients undergone an elective upper gastrointestinal endoscopy were studied. Studied patients were divided into two groups; one group was premedicated with buscopan and stropine(group I), and the other group was premedicated with diazepam and meperidien (group II). The results obtained were summarized as follows; 1) 83.0% of the group II (44/53) did not eomplain any discomfort by the procedure, but only 23.9% (8/35) of the group I showed no discopmort. The difference between two groups is statiatieally significant (p<0.005). 2) In 41 patients with previous experience of endoscopy, 22 patients from 27 of the graup Il(81.5%) did not feel any discomfort but it wes only 3 patients among 14 of the group I (21.4%) who did not feel discomfart (p<0,005). 3) In 47 patients without previous experience of endoscopy, 23 patients from 26 of the group II (88. 5%) did not show discomfort but it way only 5 patients among 21 of the group I (23.7%) (p<0.005). 4) In the patients with previous experience of endoscopy, 21 patients among 27 of the group II (77. 8%) felt better than that of the previous experience but it was only 3 patients among 14 of the group I (21.4%) (p<0.005). From the above results, we would emphasize that it is more effective to use diazepam and, meperidien as premendication for the gastrointestinal endoscopic procedure since it removes pstients apprehension rendering them a good cooperation with very minimal side effects,

A Case of Inflamatory Bowel Disease Involving Esophagus

문한규,김진도,허윤,이동완,양웅석,송근암,유방현 대한소화기내시경학회 1989 Clinical Endoscopy Vol.9 No.1

간농양을 유발한 Sparganosis 1 예

문한규,허윤,송철수,이동완,강필중,문원국,양웅석,송수복 대한내과학회 1990 대한내과학회지 Vol.39 No.5

Sparganosis, an infection transmitted to humans by sparganum, was first reported by Manson at 1882. Many cases have been reported in korea, the sites are subcutaneous tissue, fascia, body cavities, urinary tract, orbit, brain, and spinal canal. This 59-year-old male, who had a history of having eaten snakes frequently 15-20 years ago, suffered from right upper quadrant pain and intermittent fever and chills. An abdominal ultrasound revealed an echolucent area on the right lower lobe of the liver. Aspiration was done, and through a drainage tube, the parasite was expelled. On parasitologic evaluation, sparganum was confirmed. It was the first report of sparganum found in liver parenchyme in korea. We report a case of sparganosis combined with liver abscess with a review of the literature,

내시경적 담석 제거술의 임상적 고찰

문한규,양웅석,유방현,송근암,이동완,허윤 대한소화기내시경학회 1988 Clinical Endoscopy Vol.8 No.2

Endoscopic sphincterotomy (E.S.T.) has relatively low complications and is the theraphy of choice in patients with common bile duct stones. It is also an useful technique for decompression of biliary tract obstruction. Thirty two cases of patients were selected according to opedrative risks: old age, severe jaundice and recurrent or retained bile duct stones after cholecystecomy from 1986 to 1988. The results were as follows, 1) In thirty two cases nf E.S.T., male to female ratio was 1:1.46. Most frequent age was older than 40 years. (male, 84.6%, female, 84.2%). 2) Out of thirty two cases, 20 cases (62.5% were under post clholecystectomy state, 12 eases (37.5%) were obstructive jaundice. 3) Spontaneous stone passage after E.S.T. was 81.3% (26 cases), and total stone remoral rate was 87.5% (28 cases), 4) Complications of E.S.T. were noted in three cases. In the two cases of bleeding, it was spontaneously improved and a case of acute pancreatitis was treated by medical care.