Effect of Ultrasonic Melt Treatment on Solidification Microstructure of Al–5Ti–1B Alloy Containing Numerous Inoculant Particles

Soo‑Bae Kim,Jae‑Gil Jung,Young‑Hee Cho,Su‑Hyeon Kim,Kwangjun Euh,Jung‑Moo Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The effect of ultrasonic melt treatment (UST) on the solidification microstructure of an Al–5Ti–1B alloy containing highvolumefractions of Al3Tiand TiB2particles is investigated for various UST times with different melt holding times. Theas-cast Al–5Ti–1B alloy is composed of TiB2and polygonal Al3Tiparticles (present prior to UST), plate-like Al3Tiparticles,and Al grains (formed during UST and/or solidification). The UST causes a size reduction and homogeneous distributionof the TiB2-agglomerated region containing many submicron-sized TiB2particles pushed to the grain boundaries. The USTslightly decreases the size and improves the distribution of polygonal Al3Tiparticles enriched in the TiB2-agglomeratedregion. Unlike the TiB2and polygonal Al3Tiparticles, which exhibit a minor refining effect, the plate-like Al3Tiparticlesshow a significant refinement with UST application. The UST has a significant effect on the size distribution of Al grains byinducing the formation of medium-sized grains at the expense of small and large grains; however, it only has a slight effecton grain refinement. The degree of microstructure modification increases with increasing UST time but decreases with meltholding time after UST. The mechanisms for the refinement and dispersion of the TiB2and Al3Tiparticles and Al grains arediscussed considering fragmentation, nucleation, and growth behaviors induced by the UST and subsequent solidification.

에타놀 섭취 후 두부 상하위시 혈역학적 변화

김지영,김형진,홍정길 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.1

사이클론 내부의 유동특성에 관한 연구

김대욱,윤완중,손현철,박길문 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.2

For manufacturing the small-type incinerator with collecting performance of high efficiency, the experimental study was carried out with considering cyclone characteristics, tangential velocity, radial velocity and pressure of the internal cyclone. The model cyclone consisted of slick acryl was made for similarity and data of tangential inflow velocity were acquired by using a vinyl particle as a working fluid. The results obtained from the experimentation are summarized as follows : 1. Tangential velocity of internal cyclone increases as the size of particle become bigger 2. Pressure is maximum value at the wall of cyclone and decreases toward the center of cyclone. 3. The difference of pressure between maximum and minimum value is increased as the size of particle become bigger.

음낭외상시 초음파 촬영술의 유용성

김형지,진정환,이해원,이길호 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Background: Testicular rupture is a surgical emergency which command immediate repair. If surgery is delayd, a hematoma causes severe pain and loss of spermatogenesis as well as hormonal functions. Scrotal ultrasonography has been helpful in early diagnosis of testicular rupture. But disadvantage of ultrasonography include a relatively low signal-to-noise level, tissue nonspecificity, lack of contrast media, a small field of view, and dependence on the operators skill and the patients physique. Also the diagnostic accuracy, sensitivity or specificity of scrotal ultrasonography was variable in regard to authors. And so, a diagnostic accuracy of scrotal ultrasonography was evaluated in scrotal trauma. Methods·. We reviewed 38 patients of scrotal trauma from May, 1994 to March, 1998. 6 patients were treated conservatively fellowing sonography and 10 patients treated only surgical exploration without ultasonography Surgical exploration was performed in 22 case, which were evaluated by ultasound before surgical treatment. In a such 22 cases, diagnostic accuracy of scrotal ultasonography was evaluated. Results: We compared ultrasound before treatment with surgical exploration finding in a such 22 cases. The ultrasonographic features in 7(31.8%) out of 22 cases, which showed testicular ruptured, but surgical exploration revealed testicular rupture in5 and epididymal rupture in 1, simple hematocele in 1. In 15(68.2%) out of 22cases the simple hematocele was diagnosed by ultrasonography, but surgical finding feature in of the 7 cases revealed testicular rupture, epididymal rupture in 1, simple hematocele in 7. The sensitivity and specificity for the ultrasonography are 42.9% and 87.5%, and the positive and negative predictive values are 86.5%and 46.7%, respectively. Ultrasonography is low sensitive in identifying testicular rupture. Conclusion: 7trasonography include a relatively low signal-to-noise level, tissue nonspecificity, lack of contrast media, a small field of view, and dependence on the operators skill and the patients physique. Therefore, early surgical exploration for saving the testis should be performed that sonographically by seeing hypoehoic peripheral lesions and disappearance of normal ovoid form of testis, hematocele in scrotal sac.

제품보호용 포장재 개발

김정필,강재현,박대연,유성구,서길수 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.1

The environment to which a packaged-product is exposed, during handling and transportation, very often includes temporary storage. In the interest of conserving warehouse cube, packaged-products are stacked upon one another to a height which far exceeds that possible in a railcar, truck-trailer, aircraft or other conveyance. the hight to which the height to which a packaged-product may be stacked will vary depending upon the warehouse ceiling height-seldom over twenty feet. This procedure for expirimental covers testing of packaged-products weighing under 100 pounds when prepared for shipment. The BASIC requirements of this procedure consist of vibration and drop tests-which must be performed in that sequence.

관동맥 우회로술 중 경식도 심초음파도로 관찰한 도부타민 투여후와 우회로술후의 좌심실 국소벽운동

김희열,김종진,윤호중,유기동,박지원,이길환,노태호,채장성,김재형,홍순조,최규보 대한순환기학회 1997 Korean Circulation Journal Vol.27 No.8

거짓말탐지기(POLYGRAPH) 검사 사례

김정길,최효택 內務部 國立科學搜査硏究所 1996 國立 科學 搜査 硏究所 年報 Vol.28 No.-

지도자의 경쟁가치리더십과 선수만족 및 인지된 경기력의 관계

김종욱,양용길,이정수,장갑석,정종환 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.3

The purpose of this study was to identify the relationships among competing value leadership, athlete satisfaction and performance in sport field, The instrument for data collection was a questionnaire in which competing value leadership consisted as identified by Ha(1996), athlete satisfaction consisted as identified by Che(1997), and performance consisted as identified by An(2002), 350 subjects were selected from universities in Seoul by the stratified cluster sampling method, Among these selected subjects, 322 responded, and data analyses consisted of employing descriptive statistics, one-way ANOVA, multiple-regression using SPSS/PC version 11.0. First, competing value leadership and athlete satisfaction differ statistically and partially according to socio-demographic variables of athletes, Second, athlete satisfaction and performance statistically and significantly is influenced by competing value leadership of leader, Third, athlete satisfaction statistically and significantly influence performance of athletes.

열응답성 나노복합재료의 합성과 LCST에서의 열적특성

김정필,최현국,서길수 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.2

Thermal responsive nanocomposite were synthesized by copolymerization of N-isopropyl acrylamide and methylene bisacrylamide(crosslinking monomer) in an aqueous suspension of MAPTC-montorillonite at room temperature. Hydrogels containing 2.0 ∼5.0wt% of montmorillonite exhibited a lower critical solution temperature(LCST) similar to unmodified PNIPAM hydrogel (approximately 33.7℃). However, hydrogels containing 10wt% montmorillonite did not exhibit a measurable LCST. TGA result shows thermal stability of thermal responsive nanocomposite imoroved a little more than the thermal responsive polymer.

발열이 있는 호중구 감소증 환자에서의 위험도 예측인자

정중식,권운용,김규석,임용수,이중의,서길준,윤여규 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Background: Most febrile neutropenic patients are treated in an aggressive manner. However, identification of low-risk patients may enable clinicians to administer risk-based treatment. The object of this study is to certify the factors associated with increased risk at the time of visiting the emergency department. Methods: This is a retrospective study. We reviewed the medical records of 101 febrile neutropenic patients who had visited the emergency department of Seoul National University Hospital from January 1998 to August 1999. We assumed 22 risk prediction factors that could be assessed at admission to the emergency department and 5 factors that could be assessed during treatment course. To find independent risk-prediction factors, we analyzed these factors respectively by using multiple regression analysis. Results: Tachycardia(aOR=136.5), altered mentality(aOR=28.8), decreased renal function(aOR=20.1), and significant comorbidity(aOR=17,2) are the independent factors associated with higher mortality. Altered mentality(aOR=31.6) and decreased renal function(CCr < 75㎖/min, aOR=5.4) are those associated with a higher incidence of septic shock. Independent factors associated with persistent(more than 3 days) fever are the early(within 10 days) onset of fever after last chemotherapy(aOR=8.8) and the existence of new pulmonary infiltrates on a simple chest X-ray(aOR=4.3). Conclusion: The stability of vital signs, the change of mentality, the renal function, the existence of significant comorbidity, the existence of new pulmonary infiltrates, and the rate of neutropenia are clinically useful risk-prediction factors in febrile neutropenia at the time of visiting the emergency department.