Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

아세클로페낙 연질캡슬(클란자 에스 연질캡슬)의 개발

용철순,이경희,최진석,박병주,정세현,김용일,박상만,배명수,김귀자,김영식,유창훈,강성룡,유봉규,이종달,최한곤 한국약제학회 2004 Journal of Pharmaceutical Investigation Vol.34 No.1

To develop and aceclofenac soft capsule, four preparations with various solubilizers were prepared and their dissolution test was carried out. Among four preparations tested, a preparation with ethanolamine was selected a formula of aceclofenac soft capsule (Clanza S^(™), since it showed the fastest dissolution rate. Bioequivalence of aceclofenac tablet, Airtal^(™)(Dae-Woong Pharmaceutical Co., Ltd.) and aceclofenac soft capsule, Clanza S^(™)(Korea United Pharmaceutical Co., Ltd.) was evaluated according to the guideline of KFDA. Fourteen normal male volunteers (age 20-25 years old) were divided into two groups and a randomized 2×2 cross-over study was employed. After oral administration of one tablet or capsule containing 100 ㎎ of aceclofenac, blood ws taken at predetermined time intervals and the concentration of aceclofenac in plasma wa determined with an HPLC method under UV detector. The pharmacokinetic parameters (C_(max), T_(max) and AUC_(t)) were calculated and ANOVA was utilized for the statistical analysis of parameters using logarithmically transformed AUC_(t), C_(max) and T_(max) between Airtal tablet and Clanza soft capsule were 2.89%, 0.18% and 43.0%, respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals using logarithmically transformed data were within the acceptance range of log(0.8) to log(1.250(e.g.log(0.81) - log(1.23) and log(0.89) - log(1.14)) for AUC_(t) and C_(max), respectively. Thus, the criteria of the KDFA guidelines for the equivalence was satisfied, indicating that Clanza S^(™) soft capsule is bioequivalent to Airtal^(™) tablet.

원격 영상 정보 시스템의 개발

김선호,유선국,김용구,박성욱,김성림,김남현 대한의료정보학회 1996 Healthcare Informatics Research Vol.2 No.1

야뇨증 환아들의 심리사회적 특성에 대한 다기관 연구 : 행동 및 정서 문제를 중심으로

조수철,김재원,신민섭,황준원,한상원,박관현,이상돈,김경도,김건석,서홍진,이유식,정재용,김영균,문두건,남궁미경,한창희,조원열,김영식,배기수,이종국,정우영,신의진 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.6

Objectives : The aim of this study was to examine the behavioral and emotional problems associated with nocturnal enuresis in Korean children. Methods : Three hundred eighteen children with nocturnal enuresis, together with their parents, completed the Child Behavior Checklist (CBCL), Disruptive Behavior Disorder Scale according to DSM-IV (DBDS), Children's Depression Inventory (CDI), State-Trait Anxiety Inventory for Children (STAIC), and Piers-Harris Children's Self-Concept Scale (PHCSC). Ninety-three normal students were selected as the control group. Results : Compared to the normal control group, the mean scores with regard to the withdrawn, social problems, attention problems, delinquent behavior, aggressive behavior, externalizing problems and total problems profiles were significantly higher in the nocturnal enuresis group according to the CBCL results. The nocturnal enuresis group also scored significantly higher in the ADHD and ODD profiles of the DBDS. The nocturnal enuresis group was more depressed and anxious than the control group according to the results of the CDI and STAI. The mean score of the PHCSC was significantly lower in the nocturnal enuresis group when compared to the normal control group. Conclusion : The results of this study suggest that children with nocturnal enuresis in Korea have clinically relevant behavioral and emotional problems. The findings support the link between nocturnal enuresis and psychopathology in Korean children.

항갑상선제로 치료한 그레이브스병 환자의 관해예측인자

남일송,윤여일,김선규,김용현,이주영,목지오,윤석기,김철희,김영선,변동원,서교일,유명희 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

Background: Most cases of Graves' disease have been treated by antithyroid drugs in Korea. The major drawbacks of antithyroid drugs are the relative high rate of relapse and the inconvinience of long term therapy. Measurement of TBII and TRH stimulation test have been considered as the most reliable tests predicting relapse, but the predictive power is not high enough to use in clinical situation. This study was performed to find good prognostic indicators in Graves' disease patients after the discontinuation of antithyroid drug therapy. Subjects and methods : We restrospectively evaluated 96 patients with Graves' disease who showed normal TRH test at the end of antithyroid drug therapy and were followed for more than one year. Serum T3, T4, T3/T4 ratio, TBII, Anti-TPO Ab and TGAb levels were measured at the time of diagnosis and at the end of therapy. Two to three months after withdrawal of antithyroid medication, serum TSH and free T3 responses to TRH were examined. These parameters were compared between the relapse group and the remission group. Results : Among the 96 patients, 22 patients(22.9%) relapsed(Group Ⅱ) and 74 patients(77.1%) remained in remmision(Group Ⅰ). No significant difference was observed between the relapse and the remission group in clinical parameters, serum T3, T4, TSH, T3/T4 ratio, TBⅡ and Anti-TPO Ab determined before and after treatment. Serum TSH and free T3 levels measured after TRH stimulation were also similar in both groups. Serum TGAb levels determined at the end of treatment were significantly higher in the remission group(p<0.05). Relapse following the discontinuation of therapy occured within 24 months in 72.7% of the relapsed cases. After 24 months, relapse rate was reduced significantly. Conclusion : These results suggest that high serum TGAb levels could be a favorable prognostic indicator for the long term remission of Graves' disease treated with antithyroid drugs, and may suggest that Hashimoto's thyroiditis is combined with Graves' disease in those patients.

M-Commerce에서 Secure Card 기반의 결제 프로토콜 설계

김성열,조성지,유성진,배용근 조선대학교 전자정보통신연구소 2002 電子情報通信硏究所論文誌 Vol.5 No.2

In order to provide a reliable M-Commerce, a payment solution with security functions should be required. User's mobile terminals used in M-Commerce services are diversifying to cellular phone, PDA, Smart phone etc. Among them, integration of PDA's interface and mobile connection overcomes the weak point of existing cellular phone depending on information via the internet. In this paper, the Secure Card based protocol for a credit card transaction on PDA using ECC is presented. Secure Card module on this protocol encrypts user's information such as private information, delivery information and credit card information and stores it on PDA in order to free from inputting information whenever it is used. This scheme also offers security services on M-Commerce including authentication, confidentiality, integration, non-repudiation and so on.

국소침 윤마취시 Epinephrine 효과에 대한 관찰

金鳳謙,金容培,方裕鉉,朴種燮,柳在德 大韓成形外科學會 1983 Archives of Plastic Surgery Vol.10 No.1

The local anesthetics play a central and frundamental role, for they comprise, probably, the single most widely used group of durgs in the field of plastic surgery. Also many plastic surgical procedures require the use of a vasoconstrictor to reduce operative bleeding under both general and local anesthesia. Among local anesthetics, lidocaine, introduced by Lofgren in 1948, is one of most widely used local anesthetics and most frequently used for infiltration anesthesia with 0.5% to 1 0%solution. Also eqinephrine is one of the most potent and most useful vasoconstrictors for admixture with thesolution of local anesthetics for infiltration of tissue. In the clinical practice, it has been said that the concentration of lidocaine and epinephrine should be kept at the minimal level of effectiveness because of the epinephrine performs a dual service when is combined with lidocaine. In order to clarify the minimum concentration of the lidocaine and epinephrine respectively necessary for adequate duration of anesthesia, with less irritation of local tissue and less bleeding, the clinical observation and animal experiment were undertaken, and the following results were summarized. The most effective skin blanching by epinephrine was obtained with epinephrine concentration of 1 : 50,000 although some effect was still presented with epinephrine concentration of 1 : 800,000. The onset of maximum skin blanching following the local infiltration of lidocaine with epinephrine(1 : 50,000 to 1 : 400,000) was within 5 minutes and was lasting 20 to 40 minutes. When the skin incision was made 5 minutes to 15 minutes following local infiltration of epinephrine, the amount of bleeding was markedly decreased and no significant difference in the time of hemostasis was noticed(p〉0.1). Also no significant difference in the time of hemostasis was noticed in the different concentration (1 : 100,000 and 1 : 200,000) of epinephrine(p〉0.1). The optimum concentration of epinephrine is between 1 : 200,00 to 1 : 400,000 solution and the optimum concentration of lidocaine is 0.5%.

중원지역의 설화를 동화화하기 위한 연구 및 개발

김정란,유소영,박혜숙,박용식 건국대학교 중원인문연구소 1999 중원인문논총 Vol.19 No.-

This study describes the research and development of fairy tales from the folk tales in Joung-Won area. The need for this problem was assessed through the special training course of fairy tale writing sponsored by Cho-Bang. The first step was the study of the suitable definition and types of fairy tales. Assuming that the problem in defining the field of folk tales is the lack of common agreement in the labels, definitions and standard classification models of folk tales, literature related to these areas were reviewed. The application of this research and development will be the fairy tale writing. The next step was therefore to select the folk tales suitables to the fairy tale writing and to explore the Joong-Won area related to these stories. By this study we found that Joon-Won area's folk tales have few supernatural, fantastic elements which are the common characteristics of fairy tales. Considering the lack of these characteristics, we selected and wrote the story of "General Shin Lip", "the funny stories", "the story of the Castle Mago"(from the Nam mountain folk tales), "princess Ari and prince Koko"(from the folk tales of Kye-Myung mountain), etc... We found the development of the fairy tales a meaningful and rewarding work and experience. Our purpose to gain the basic knowledge in the development of this field has been met. But these fairy tales need to be visualized to be published. We should prepare for the implementation of practical application of this study and development: contact with a higher administrator in Joong Won area, discussion on the support possibility, visual production, addition of necessary materials, etc... Only the surface has been touched in this study. But the authors hope that in the near future, we will be able to create the new cultural work needed in the Joon-Won area.

제 2형 당뇨병 환자에서 혈중 Metalliproteinase-9의 농도

김상용,김희중,주유철,최동현,배학연 조선대학교 2000 The Medical Journal of Chosun University Vol.25 No.2

Purpose : Diabetic nephropathy is a serious complication of diabetes and accounts for much of its morbidity and mortality. It is well known that the overt clinical phase of diabetic nephropathy is preceded for many years by the presence of microalbuminuria. Microalbuminuria is thought to be a marker of widespread vascular damage and may underlie the propensity toward severe extrarenal vascular disease in microalbuminuric patients. Metalloproteinase-9 has a broad substrate specificity for native collagens as well as proteoglycan and elastin. One study reported that an increased plasma metalloproteinase-9 concentration precedes the development of microalbuminuria in type 2 diabetic patients. Another study reported that a high glucose concentration cause a abnormality on the activity of metalloproteinase by the mesangeal cell. The purpose of the present study was to examine whether palsma metalloproteinase-9 concentrations are altered at various complications in type 2 diabetic patients. Methods : Sixty patients with type 2 diabetes and thirty healthy control were recruited for the present study. No patient had any malignancy or history of heart disease, liver disease, collagen disease. We recorded age, duration of diabetes, and blood pressure. After an overnight fast, blood was drawn from an antecubita1 vein of measurement of glucose, metalloproteinase-9, HbA1C, and serum creatinine. To measure plasma concentration of metalloproteinase-9, a one step sandwich enzyme immunoassay using two monoclonal antibodies was used. Patients were divided into two group according to the presence or abscence of microalbuminuria. The groups were then compared with regard to clinical and laboratory characteristics and serum concentration of metalloproteinase-9. Results : The mean serum levels of metalloproteinase-9 in diabetic patients (62.32±25.83ng/㎖) were significantly higher than in healthy controls(12.92±4.97ng/㎖) (p<01). The mean serum levels of metalloproteinase-9 in diabetic patients with microalbuminuria(81.16±41.43ng/㎖) were significantly higher than in those with normoalbuminuria(31.48±7.34ng/㎖) (p<01) and much more than in healthy control(12.92±4.97ng/㎖) (p<05). Furthermore, the severity of nephropathy were closely associated with the serum metalloproteinase-9 level and the serum metalloproteinase-9 level was significantly correlated with microalbuminuria. The mean serum level of metalloproteinase-9 in diabetic patients with retinopathy(61.74±39.07ng/㎖) was significantly higher than in those with no retinopathy(34.98±9.02ng/㎖) (p<05). But, in diabetic patients with normoalbuminuria, there is no difference between the groups with retinopathy versus no retinopathy. Conclusion : In summary, a sustained increase in serum metalloproteinase-9 in patients with type 2 diabetes is associated with a high risk for the development of microalbuminuria. The results of this study suggest that the serum rnetalloproteinase-9 was a useful and noninvasive marker for the development of diabetic nephropathy. It could be also used to predict the development of diabetic complications and to assess therapeutics or the prognosis of diabetes. The usefulness of this model will be clarified by a larger scale and serial study.

매복 미맹출 제 1대구치의 외과적 노출과 교정력을 이용한 견인의 치험례

유정민,김종수,김용기 大韓小兒齒科學會 1996 大韓小兒齒科學會誌 Vol.23 No.4

It is a relatively rare clinical experience to see the impacted first molar. The first permanent molar is the dey in normal occlusion. Abnormal eruption of the first permanent molars would inflict normal development of dental arches and give rise to abnormal root resorption of the adjacent teeth. Therefore, the abnormally erupted first permanent molars should be detected and treated early in order to obtain proper occlusal guidance in mixed dentition period. This report presents two cases on distally tilted and impacted mandibular first molars which were treated by surgical exposure and orthodontic traction using facial mask.