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마이크로파-수열 합성법을 이용한 나노 수산화아파타이트 합성과 특성평가
한재길,이치우,이병택,Han, Jae-Kil,Lee, Chi-Woo,Lee, Byong-Taek 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.2
Nano-sized hydroxyapatite (HAp) powders were synthesized by a microwave-hydrothermal method using $H_3PO_4\;and\;Ca(OH)_2$ as starting materials. The applied microwave powers and mole ratio of Ca/P were served as powerful factors in the synthesis of calcium phosphate. In the case of relatively low microwave power of 450 Wand Ca/P ratio of 1.57, the mixed calcium phosphate compounds were detected in the synthesized powders. But in the case of running at 550 Wand 1.67(Ca/P), the synthesized powder showed the monophase of HAp having two kinds of morphologies. One was a needle shape with $5\~15\;nm$ in width and $20\~50\;nm$ in length, and the other was a spherical shape of $10\~40\;nm$ in diameter.
나노 Ag spot-coated TiO<sub>2</sub>-SrO 복합분체의 합성과 광촉매 활성 평가
한재길,김형철,홍원석,최성창,Han, Jae-Kil,Kim, Hyeong-Chul,Hong, Won-Seok,Choi, Sung-Chang 한국재료학회 2008 한국재료학회지 Vol.18 No.7
Nano-sized $TiO_2$-60 wt% SrO composite powders were synthesized by a sol-gel method using titanium isopropoxide and $Sr(OH)_2\;{\cdot}\;8H_2O$ as precursors. 3, -5, -7 wt%Ag spot-coated $TiO_2$-60 wt% SrO composite powders were synthesized by a Ag electroless deposition method using $TiO_2$-60 wt% SrO composite powders calcined at $1050^{\circ}C$, which mainly exhibited the $SrTiO_3$phase. However, a small number of rutile $TiO_2$, $Sr_2TiO_4$ and $SrO_2$ phases were also detected. In the Ag spot-coated powders synthesized by electroless deposition, nano-sized particles about 5-25 nm in diameter adhered to the $TiO_2$-60 wt% SrO composite powders. The photocatalytic activity of Ag spot-coated $TiO_2$-SrO and $TiO_2$-SrO composite powders for degradation of phenol showed that all of $TiO_2$-SrO composite powders were highly active under UV light irradiation. 7 wt%Ag spot-coated $TiO_2$-60wt.%SrO composite powders had a relatively higher photocatalytic activity than did $TiO_2$-SrO composite powders under visible light.
ZrO<sub>2</sub>-Ag의 복합화 공정에 따른 기계적 특성 및 미세조직 평가
여인철,한재길,강인철,Yeo, In-Chul,Han, Jae-Kil,Kang, In-Cheol 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.6
This paper introduces an effect of a preparing $ZrO_2$-Ag composite on its mechanical properties and microstructure. In present study, $ZrO_2$-Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into $ZrO_2$ powder during wetting dispersive milling in D.I. water. Each sample was sintered at $1450^{\circ}C$ for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated $ZrO_2$ showed homogeneously dispersed Ag in $ZrO_2$ in where pore defect did not appear. However, $ZrO_2$-nano Ag and $ZrO_2$-micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.
급속승온공정을 이용한 사출성헝된 Fe 소결체의 미세조직 및 소결거동
김기현,한재길,유지훈,최철진,이병택,Kim Ki-Hyun,Han Jae-Kil,Yu Ji-Hun,Choi Chul-Jin,Lee Byong-Taek 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.6
Using the nano Fe powders having 50 nm in diameter, Fe compact bodies were fabricated by injec-tion molding process. The relationship between microstructure and material properties depending on the volume ratio of powder/binder and sintering temperature were characterized by SEM, TEM techniques. In the compact body with the volume percentage ratio of 45(Fe powder) : 55(binder), which was sintered at $700^{\circ}C,$ the relative density was about $97{\%},$ and the values of volume shrinkage and hardness were about $66.3{\%}$ and 242.0 Hv, respec-tively. Using the composition of 50(Fe powder) : 50(binder) and sintered at $700^{\circ}C,$ the values of relative density, volume shrinkage and hardness of Fe sintered bodies were $73.3{\%},\;47.6{\%}$ and 152.8 Hv, respectively. They showed brittle fracture mode due to the porous and fine microstructure.
수열흡착법을 이용한 은 점코팅된 구리 나노분말의 합성과 미세조직
김형철,한재길,Kim, Hyeong-Chul,Han, Jae-Kil 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.6
Ag spot-coated Cu nanopowders were synthesized by a hydrothermal-attachment method (HA) using oleic acid capped Ag hydrosol. Cu nano powders were synthesized by pulsed wire exploding method using 0.4 mm in diameter of Cu wire (purity 99.9%). Synthesized Cu nano powders are seen with comparatively spherical shape having range in 50 nm to 150 nm in diameter. The oleic acid capped Ag hydrosol was synthesized by the precipitation-redispersion method. Oleic acid capped Ag nano particles showed the narrow size distribution and their particle size were less than 20 nm in diameter. In the case of nano Ag-spot coated Cu powders, nanosized Ag particles were adhered in the copper surface by HAA method. The components of C, O and Ag were distributed on the surface of copper powder.
10 wt%, 20 wt%Li-TiO<sub>2</sub> 복합분말의 합성과 광촉매 활성평가
김형철,한재길,Kim, Hyeong-Chul,Han, Jae-Kil 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.1
10 wt.% and 20 wt.%$Li-TiO_2$ composite powders are synthesized by a sol-gel method using titanium isopropoxide and $Li_2CO_3$ as precursors. The as-received amorphous 10 wt.%$Li-TiO_2$ composite powders crystallize into the anatase-type crystal structure upon calcination at $450^{\circ}C$, which then changes to the rutile phase at $750^{\circ}C$. The asreceived 20 wt%$Li-TiO_2$ composite powders, on the other hand, crystallize into the anatase-type structure. As the calcination temperature increases, the anatase $TiO_2$ phase gets transformed to the $LiTiO_2$ phase. The peaks for the samples obtained after calcination at $900^{\circ}C$ mainly exhibit the $LiTiO_2$ and $Li_2TiO_3$ phases. For a comparison of the photocatalytic activity, 10 wt.% and 20 wt.% $Li-TiO_2$ composite powders calcined at $450^{\circ}C$, $600^{\circ}C$, and $750^{\circ}C$ are used. The 20 wt.%$Li-TiO_2$ composite powders calcined at $600^{\circ}C$ show excellent efficiency for the removal of methylorange.
유성 볼밀을 통해 제조된 TiO<sub>2-x</sub>N<sub>x</sub> 광촉매의 가시광 활성도와 NH<sub>3</sub>양 및 분쇄시간과의 상관 관계
강인철,고준빈,한재길,김광희,최성창,Kang, In-Cheol,Ko, Jun-Bin,Han, Jae-Kil,Kim, Kwang-Hee,Choi, Sung-Chang 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.3
A visible-light photoactive $TiO_{2-x}N_x$ photocatalyst was synthesized successfully by means of cogrinding of anatase-$TiO_2(a-TiO_2)$ in $NH_3$ ambient, followed by heat-treatment at $200^{\circ}C$ in air environment. In general, it is well known that the grinding-operation induces phase transformation of a-$TiO_2$ to rutile $TiO_2$. This study investigates the influence of the amount of $NH_3$ gas on the phase transformation rate of a-$TiO_2$ and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a-$TiO_2$ to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than $NH_3$ amount injected, which means that the doping amount of nitrogen into $TiO_2$ more effective to mechanical energy than $NH_3$ amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.
드라이버 헤드의 어택각과 타격점 변화가 골프볼의 비거리에 미치는 영향
김광혁(Kim, Kwang-Hyeuk),한재길(Han, Jae-Kil),강인철(Kang, In-Cheol) 한국체육과학회 2018 한국체육과학회지 Vol.27 No.4
This study was focused on variation of ball"s trajectory depending on the attack angle and impact position on the clubface between clubhead and ball. At 115 mph(mile per hour) of an average clubhead speed, total distance, carry, ball speed, rpm of ball, top height and launch angle were compared according to the change of the attack angle (0°, 3°, 6°) and impact position (‘center’, ‘5 ㎜ up’, ‘5 ㎜ down’, ‘10 ㎜ up’), respectively. Total distance was increased with larger launch angle, and launch angle increased with larger attack angle. On the other hand, total distance was decreased with higher rpm, and rpm increased depending on the impact position in the order of ‘up’, ‘center’, ‘down’ due to the gear effect. Generally, total distance of ball was longer with increasing of ball speed, but this study showed that total distance of ball was longer even lower ball speed in condition of the ‘up’ impact position, because of lower rpm due to gear effect. But outside the normal impact range as like the impact position of ‘10 ㎜ up’, gear effect can not be fully expected. In other words, ‘10 ㎜ up’ impact position showed a gear effect resulting to lower rpm, but it showed lower ball speed due to outside the effective impact range. In result, the best for total distance of ball was under condition of an attack angle 6° and impact position at ‘5 ㎜ up’. On contrary, the minimum for total distance of ball was under condition of an attack angle 0° and impact position at ‘5 ㎜ down’ due to low launch angle, high rpm and ineffective delivery of clubhead energy to ball. Finally it have to be considered an attack angle, gear effect and effective delivery of clubhead energy to ball for the most total distance of ball.
김광혁(Kim, Kwang-Hyeuk),최재원(Choi, Jae-Won),강인철(Kang, In-Cheol),한재길(Han, Jae-Kil) 한국체육과학회 2018 한국체육과학회지 Vol.27 No.4
The purpose of the study is to provide objective data on the performance of golf balls by comparing ball compression and coefficient of restitution(COR) using seven types of products. Seven types of golf balls weighed 45.442 to 45.711 g, while the outside diameter was measured at 42.703 to 42.773 mm, with a distribution of 0.59 % in weight and 0.16 % in diameter. As a result of measuring the outer diameter of a golf ball by increasing the compression load from 200 lb to 300 Ibrahim, the four-piece golf ball was altered by 0.600 mm and the three-piece golf ball was changed by 0.638 to 0.820 mm. The coefficient of restitution(COR) of golf balls tends to decrease to 0.852, 0.846 and 0.801 as the ball speed of firing was increased to 80, 85 and 125 mph. After measuring the deformation of a golf ball with a high-speed camera, the deformation of the ball was not related to coefficient of restitution and increased in cases of large changes in compressive strength. The results of the seven types of golf swing robot tests showed a ball speed of 2.3 mph, a total distance of 6.023 m, and a standard deviation of 1.4 % and 2.2 %. The difference in ball rotation was 361 rpm, which resulted in a relatively large standard deviation of about 14 %.