Microstructure‑Strengthening Interrelationship of an Ultrasonically Treated Hypereutectic Al–Si (A390) Alloy

Soo‑Bae Kim,Young‑Hee Cho,Jae‑Gil Jung,Woon‑Ha Yoon,Young‑Kook Lee,Jung‑Moo Lee 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6

Ultrasonic melt treatment (UST) was applied to an A390 hypereutectic Al–Si alloy in a temperature range of 750–800 °Cand its influence on the solidification structure and the consequent increase in strength was investigated. UST at such a hightemperature, which is about 100 °C above the liquidus temperature, had little effect on the grain refinement but enhanced thehomogeneity of the microstructure with the uniform distribution of constituent phases (e.g. primary Si, α-Al and intermetallics)significantly refined. With the microstructural homogeneity, quantitative analysis confirmed that UST was found tosuppress the formation of Cu-bearing phases, i.e., Q-Al5Cu2Mg8Si6, Al2Cuphases that form in the final stage of solidificationwhile notably increasing the average Cu contents in the matrix from 1.29 to 2.06 wt%. A tensile test exhibits an increasein the yield strength of the as-cast alloy from 185 to 208 MPa, which is mainly associated with the solute increment withinthe matrix. The important role of UST in the microstructure evolution during solidification is discussed and the mechanismcovering the microstructure-strengthening interrelationship of the ultrasonically treated A390 alloy is proposed.

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.

하악골 절제술후 재이식된 돌결자가골 재이식 : 치험 3례

김 식,김수관,김운규,김수민,류종희,이준길,조경안,김수흥,정태영,여환호 대한악안면성형재건외과학회 2001 Maxillofacial Plastic Reconstructive Surgery Vol.23 No.2

We described three cases of immediate reimplantation of a frozen-thawed autogenous mandible composed of a mixture of iliac bone, marrow, and particulate hydroxyapatite in tumors of the mandible. Acceptable outcomes were obtained in three patients who underwent immediate autogenous mandibular graft reconstruction. The conditions leading to successful outcome of the procedure are also discussed. Reimplantation of frozen autogenous lesioned mandible was performed in three patients with mandibular tumors. Two reimplanted grafts survived without complications following surgery. One case had postoperative infection that resolved with appropriate antibiotic treatment. There were no recurrences of the primary lesions. Satisfactory facial contour after surgery was achieved. These results are most promising, and we believe that, with further refinement, this technique will offer a new and acceptable modality for facial reconstruction in patients with cancer.

모터내장형 주축의 온도분포해석에 관한 연구

김용길,김수태 國立 昌原大學校 産業技術硏究所 1997 産技硏論文集 Vol.11 No.-

Unsteady-state temperature distributions in the motor integrated spindle for a high precision machine tool are studied. For the analysis, three dimensional model is built for the high precision spindle. The three dimensional model includes the estimation on the mount of heat generation of bearing and built-in motor and the thermal characteristic values such as heat transfer coefficient. Temperature distributions are computed using the finite element method. Analysis results are compared with the measured data. Analysis show that temperature distributions of a motor integrated spindle can be estimated reasonably using the three dimensional model through the finite element analysis.

更生保護事業의 活性化 方案

金秀吉 濟州大學校 法과政策硏究所 1996 法과 政策 Vol.- No.2

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.

公務員犯罪의 要因分析과 그 對策에 關한 硏究

金秀吉 제주대학교 1983 논문집 Vol.16 No.2

This study was conducted to consider a counter-measure to meet Korea public official's crime through the analysis and investigation of its general situation and factors. In Korea, a certain specified factor does not exert influence on the occurance of the public official's crime; rather, various factors(politic, economic, socia1, and cultural ones including the problems of remuneration and administrative control) jointly exercise effects upon it. Therefore, in order to prevent the public official's crime the government has to consider a reasonable, long-term counter-measure which can remove various, direct or indirect factos affecting the occurence of public official's crime. The counter-measure to cope with the crime of Korean public official is as follows: 1. Public officials have to reform their prevented their views of public duty and establish their democratic views of public servant by themselves. 2. Politic corruption must be prevented, and politic stability established, too. 3. The governmment must pay public officials more amount than mminimum cost of living as salary and improve reasonably its annuity system. In addition, the government must rationalize personnel management system and intensify education and training for improving the qualities of the whole civil servants. 4. Economic balance and stability must be established. 5. The whole people have to establish sound social climate through the enhancement of their sense of value and their spirit of obeying laws. 6. The government has to make its best to prevent the occurence of its official's crime, and the public official who commit crime must be punished in strict fairness.

감꼭지나방(나비목:감꼭지나방과)의 발육생태

김정화,김길하,조수원,박은철,박형진 충북대학교 첨단원예기술개발연구센터 2000 연구보고서 Vol.5 No.-

충북 영동의 감나무 가로수에서 감꼭지나방(Stathmopoda masinissa)을 채집하여 온도 25±1℃,광주기 16L:8D, 상대습도 85%의 실내조건에서 이들의 발육생태를 조사하였다. 각 충태별 발육일수는 알기간 7.4일, 유충기간 34.8일, 번데기기간이 15.5일이었다. 1령에서 5령의 영기간은 각각 3.5일, 4.2일, 5.2일, 6.5일, 15.4일이었으며, 유충의 두폭은 각각 0.20, 0.40, 0.65, 0.87, 1.07mm이었다. 용화율과 우화율은 각각 68.0%, 59.9%이었다. 성충 수명은 수컷이 6.2일, 암컷이 10.1일이며, 암컷 한 마리당 평균 산란수는 24.4개였다. Persimmon fruit moth, Sathmopoda masinissa, collected from roadside persimmon trees planted as shade trees in yeongdong area was used to investigate their developmental ecology under laboratory condition; 25±1℃, 16L : 8D and 85% RH. Developmental periods for eggs, larvae, and pupae were 7.4, 34.8 and 15.5 days, respectively. The duration for each larval instar from the 1st to the 5th was 3.5, 4.2, 5.2, 6.5 and 15.4 days, respectively, and the head capsule width of corresponding stage was 0.20, 0.40, 0.65, 0.87 and 1.07mm. Rates of pupation and emergence were 68.0 and 59.9%, respectively. Longevity of adult males was 6.3 days while that of females was 10.1 days. Average fecundity was 25.4 eggs.

방위특징 탐지 단순신경세포들의 배열순서에 관한 연구

김길중,김정국,서광명,서용수 동서대학교부설연구소 1998 연구소 논문집 Vol.3 No.-

Cells in avisual cortex line in columns which are perpendicular to the cortical surface and the cortical cells in a column prefer to respond to an orientation of each line segments of an sesory image. orientation preference of each cortical column is highly correlated to those of nearbycolumns and varies smoothly anlong the surface of the cortex. To elucidate the mechanism of this columnar organization, we propose a simple model consisting of orientation selective neruons(OSNs) with local facilitation and lateral inhibition. it is playsible that modifiable connections play an important role in forming and refining the organization togher with the sensory experience. Thus the feed-forward connections between OSNs and LGN cells are modifiable. The interactions between OSNs in the same layer take place by way of feedback pathways and are excitatory and inhibitory. The behavior of the model is described by a STM equations of Growwberg and critical parameter of negative one dimensional ??G function, σ would give variety to the differences in detected orientations.

여름철 참나무속의 이소프렌 배출속도 비교에 관한 연구

김조천,김기준,홍지형,선우 영,임수길 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.1

In order to compare the NVOC (Natural Volatile Organic Compound) emission rates from oak trees, the emission rates of isoprene were quantitatively measured in situ based on tree species and region. As a result, the emission rates from Quercus serrata T. were found to be 1000 times greater than those from Quercus acutissima C. However, the emission rates at the Chiri and Gumsung mountain sites did not show any significant differences in summer. Cuvette tests using four different oak species also supported that there was a tremendous difference in emission rates between Quercus serrata T. and Quercus acutissima C. It was found that the emission rates from the trees were highest on the order of Quercus serrata T., Quercus aliena B., Quercus acutissima C. and Quercus variabilis B.