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Seed를 이용한 일방향응고 Ti-46A1-1.5Mo-0.2C 합금의 크리프 특성
李鎬年,丁仁洙,吳明勳,山口正治,韋當文 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.1
Creep properties of directionally solidified Ti-46A1-1.5Mo-0.2C alloys with well aligned lamellar microstructure have been dramatically improved. The ingots were manufactured by seeding technique directional solidification. Directionally solidified Ti-46A1-1.5Mo-0.2C alloys showed excellent creep properties. However, the creep resistance decreased as the angle between lamellar orientation and loading axis increased. It is found that the control of the lamellar orientation is most important to improve the creep resistance of TiAI alloys. In the results of TEM analysis of creep specimen before and after creep test, it was found that no carbides were formed before creep test. But, after creep test, carbides were formed in γ lath, γ / γ interfaces, γ / α_2 interfaces and dislocations. In the case of creep test at 750℃, the quantity of carbides found in dislocations decreased as the load level increased. It was thought that superior thermal stability of Ti-46A1-1.5Mo-0.2C alloy suppressed the dynamic recrystallization and the coarsening of the lamellar microstructure, and the excellent creep resistance was maintained for long time due to this thermal stability.
α상분율의 변화가 층상조직 TiAl 합금의 열적안정성에 미치는 영향
金聖雄,이호년,吳明勳,山口正治,韋當文 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.6
The thermal stability of lamellar microstructure in TiAl-Mo PST crystals containing C or Si was investigated. In addition, the variation of α-phase volume fraction in Ti-Al-Mo-(C, Si) systems was also investigated at several temperatures. It was found that Ti-46Al-1.5Mo-O.2C and Ti-46Al-1.5Mo-1.0Si alloys were very stable during heat treatments at various heating rates and temperatures. Moreover, the, α-phase volume fraction of Ti-46A1-1.5Mo-0.2C and Ti-46A1-1.5Mo-1.OSi alloys (stable composition) was less changed than those of Ti-47Al and Ti-46Al-1.5Mo alloys (unstable composition). From these results, the instability of the latter alloys was thought to be resulted from relatively higher variation of α-phase volume fraction during heating. Therefore, it could be suggested that the variation of α-phase volume fraction is an important factor that control the thermal stability of lamellar microstructure.
( Ho Myung Lee ),( Chang Wook Nam ),( Yun Kyeong Cho ),( Hyuck Jun Yoon ),( Hyoung Seob Park ),( Hyung Seop Kim ),( In Sung Chung ),( Yun Seok Heo ),( Seung Ho Hur ),( Yoon Nyun Kim ),( Kwon Bae Kim ) 대한내과학회 2014 The Korean Journal of Internal Medicine Vol.29 No.5
Background/Aims: Although complex bifurcation stenting in patients with nonleftmain (LM) bifurcation lesions has not yielded better clinical outcomes thansimpler procedures, the utility of complex bifurcation stenting to treat LM bifurcationlesions has not yet been adequately explored. Methods: In the present study, patients who underwent LM-to-left anterior descending(LAD) coronary artery simple crossover stenting to treat significantde novo distal LM or ostial LAD disease, in the absence of angiographically significantostial left circumflex (LCX) coronary artery disease, were consecutivelyenrolled. The frequencies of 3-year major adverse cardiovascular events (MACEs;cardiac death, myocardial infarction, and target lesion revascularization), wereanalyzed. Results: Of 105 eligible consecutive patients, only 12 (11.4%) required additionalprocedures to treat ostial LCX disease after main vessel stenting. The mean percentagediameter of ostial LCX stenosis increased from 22.5% ± 15.2% to 32.3% ±16.3% (p < 0.001) after LM-to-LAD simple crossover stenting. The 3-year incidenceof MACEs was 9.7% (cardiac death 2.2%; myocardial infarction 2.2%; target lesionrevascularization 8.6%), and that of stent thrombosis 1.1%. Of seven cases (7.5%)requiring restenosis, pure ostial LCX-related repeat revascularization was requiredby only two. Conclusions: Simple crossover LM-to-LAD stenting without opening of a struton the LCX ostium was associated with acceptable long-term clinical outcomes.
권호장(Ho Jang Kwon),하미나(Mina Ha),김붕년(Bung Nyun Kim),임명호(Myung Ho Lim) 대한소아청소년정신의학회 2016 소아청소년정신의학 Vol.27 No.4
Attention-deficit hyperactivity disorder (ADHD) is a common, childhood-onset, neuropsychiatric disorder with an estimated prevalence of 2–7.6% in Korean children. Although the etiology of ADHD is not well understood, evidence from genetic factor and environmental factor studies suggests that ADHD results from a gene environmental interaction. In the current study, we reviewed the evidence for and clinical implications of the hypothetical roles of organophosphate pesticides, organochlorine pesticides, polychlorinated biphenyls, phthalate, bisphenol, polyfluoroalkyl chemicals, polycyclic aromatic hydrocarbons, mercury, lead, arsenic, cadmium, manganese, tobacco, alcohol as harmful risk factors in the development of ADHD.
또래중재 역할놀이가 자폐성 유아의 사회적 행동에 미치는 효과
김호년 ( Ho Nyun Kim ),도명애 ( Myung Ae Do ) 한국정서·행동장애아교육학회(구 한국정서학습장애아교육학회) 2012 정서ㆍ행동장애연구 Vol.28 No.2
본 연구의 목적은 또래중재 역할놀이 활동이 자폐성 유아의 사회적 행동(긍정적 행동, 부정적 행동)에 미치는 효과를 알아보기 위하여 소아정신과에서 자폐증으로 진단을 받은 자폐성 유아 3명과 일반유아 18명(또래중재 유아 6명 포함)으로 역할놀이를 실시하고 그 결과를 빈도표와 그래프로 제시하였다. 본 연구의 목적을 이루기 위하한 적용한 연구설계는 ABA실험설계로 기초선, 중재기간, 제2기초선 기간의 데이터를 측정하였다. 실험기간은 총 34회기로 기초선 기간은 5회기, 중재기간은 24회기, 제2기초선 기간은 5회기로 실시하였다. 본 연구의 결과는 다음과 같다. 첫째, 또래중재 역할놀이가 자폐성 유아의 긍정적 사회적 행동을 증가시켰다. 둘째, 또래중재 역할놀이가 자폐성 유아의 부정적 사회적 행동을 감소시켰다. 또래중재 역할놀이가 자폐성 유아 3명 모두에게 기초선 단계에서 보이지 않았던 긍정적 사회적 행동의 증가에 영향을 가져왔다. 중재기간이 끝난 후에도 자폐성 유아의 긍정적 사회적 행동이 상당히 유지되었다. 이러한 결과는 또래중재 역할놀이가 자폐성 유아의 사회적 행동의 개선에 유용하다는 것을 나타낸다. The purposes of this study are to find out the effects of the peer intervention role playing on the social behaviors of the autistic infant. The subjects of this study were three infants with autistic disabilities as well as 18 infants without disabilities(including six peer intervention infants). ABA experimental design was used to allow autistic infants and peer infants without disabilities to do role-playing. The baseline measurement had five sessions during 3 weeks, the intervention measurement had a total of 24 sessions during 6 weeks, and the second baseline measurement had five sessions during 3 weeks. The results of this study are as followings: First, the peer intervention role-playing increased positive social behaviors(not seen in the basic phase) of three autistic infants. Second, the peer intervention role-playing decreased negative social behaviors of three autistic infants. These results indicate that peer intervention role-playing is effective for improvement of social behaviors of autistic infants.
Lee, Ho-Nyun,Shin, Chi-Ho,Hwang, Duck Kun,Kim, Haekyoung,Oh, Kyeongseok,Kim, Hyun-Jong Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.644 No.-
<P><B>Abstract</B></P> <P>In this study, a novel pressurized polyol method is proposed to synthesize aluminum-doped ZnO (AZO) nanoclusters without utilizing additional thermal treatment to avoid the merging of nanoclusters. The size of the AZO nanoclusters range from 100 to 150nm with a resistivity of 204Ωcm. The AZO nanoclusters primarily consist of approximately 10-nm nanocrystals that form a spherically clustered morphology. A two-stage growth model has been proposed based on the results of scanning electron microscopy and transmission electron microscopy images, nanocluster sizes, and X-ray diffraction patterns. The primary AZO nanocrystals first nucleate under pressurized conditions and then spontaneously aggregate into larger nanoclusters. Optically, the AZO nanoclusters exhibit a significant decrease in the near-infrared (NIR) transmittance compared to pure ZnO nanoparticles. The NIR blocking efficiency of AZO nanoclusters reached 85%. Moreover, the doping efficiency, resistivity, and NIR transmittance of AZO nanoclusters are influenced by the reaction time in the pressurized polyol solution. On the other hand, the reaction time has no effect on the particle size and crystallinity. An optically transparent coating for the AZO nanoclusters, which consisted of iso-propanol solvent and ultraviolet-curable acrylic binder, was also demonstrated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Low-temperature pressurized polyol method synthesized Al-doped ZnO nanoclusters. </LI> <LI> Reaction time affected the doping efficiency, resistivity, and NIR transmittance. </LI> <LI> The near-IR blocking efficiency of Al-doped ZnO (AZO) nanoclusters reached 85%. </LI> <LI> AZO nanocluster coatings could be used for heat reflectors or artificial glasses. </LI> </UL> </P>
김윤년(Yoon Nyun Kim),배장호(Jang Ho Bae),신경목(Kyeung Mok Shin),한성욱(Sung Wook Han),허승호(Seung Ho Huh),김기식(Kee Sik Kim),김권배(Kweon Bae Kim) 대한내과학회 1997 대한내과학회지 Vol.52 No.1
N/A Objectives : Among the current therapeutic options for paroxysmal supraventricular tachycardias, only surgery and ablative techniques are curative. However, surgery is associated with substantial cost, morbidity, and rarely death. Recently, catheter ablation techniques have been developed to treat paroxysmal supraventricular tachycardias. These techniques are effective and low-risk curative treatment for supraventricular tachycardias. This article shall describe our clinical experiences in radiofrequency catheter ablation for supraventricular tachycardias and review the literature. Methods: The study population consisted of 154 patients with supraventricular tachycardias from January 1993 to August 1995. Eighty one patients were men and seventy three patients were women, and their mean age was 41.29±15.41 years. Radio-frequency currents(mean) were applied through a catheter electrode positioned against the mitral or tricuspid annulus or a branch of the coronary sinus or atrioventricular node. Results: Among 154 patients, the mechanisms for paroxysmal supraventricular tachycardias were found to be atrioventricular reentrant tachycardia involving a concealed accessory pathway in 51(33.1%), Wolff-Parkinson-White syndrome in 57(37%), and atrioventricular nodal reentrant tachycardia in 46 (29.9%). Successful outcomes were achieved in 46 of 46 patients(100%) with atrioventricular nodal reentrant tachycardia, 7 of 8 patients(87.5%) with double accessory pathways, 69 of 72 patients(95.8%) with left-sided accessory pathway, and 19 of 28 patients (67.9%) with right-sided accessory pathway. Total 141 of 154 patients(91.6%) with supraventricular had a successful outcome with radio- frequency current application(mean). Conclusions: Radiofrequency catheter ablation techniques are highly effective in ablating accessory pathways or modifying atrioventricular node, with low morbidity and no mortality.