Zr₂WP₂O₁₂ 세라믹스의 합성과 소결거동 연구

김용현,김남옥,이상진,Kim, Yong-Hyeon,Kim, Nam-Ok,Lee, Sang-Jin 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.6

$Zr_2WP_2O_{12}$ powder, which has a negative thermal expansion coefficient, was synthesized by a solid-state reaction with $ZrO_2$, $WO_3$ and $NH_4H_2PO_4$ as the starting materials. The synthesis behavior was dependent on the solvent media used in the wet mixing process. The $Zr_2WP_2O_{12}$ powder prepared with a solvent consisting of D. I. water was fully crystallized at $1200^{\circ}C$, showing a sub-micron particle size. According to the results obtained from a thermal analysis, a $ZrP_2O_7$ was synthesized at a low temperature of $310^{\circ}C$, after which it was reacted with $WO_3$ at $1200^{\circ}C$. A new sintering additive, $Al(OH)_3$, was applied for the densification of the $Zr_2WP_2O_{12}$ powders. The cold isostatically pressed samples were densified with 1 wt% $Al(OH)_3$ additive or more at $1200^{\circ}C$ for 4 h. The main densification mechanism was liquid-phase sintering due to the liquid which resulted from the reaction with amorphous or unstable $Al_2O_3$ and $WO_3$. The densified $Zr_2WP_2O_{12}$ ceramics showed a relative density of 90% and a negative thermal expansion coefficient of $-3.4{\times}10^{-6}/^{\circ}C$. When using ${\alpha}-Al_2O_3$ as the sintering agent, densification was not observed at $1200^{\circ}C$.

Electrical, structural and etching characteristics of ZnO:Al films prepared by rf magnetron

김용현,이경석,Taek Sung Lee,정병기,성태연,Won Mok Kim 한국물리학회 2010 Current Applied Physics Vol.10 No.2

Al doped ZnO (AZO) films were prepared by radio frequency (rf) magnetron sputtering with varying substrate temperature, working Ar gas pressure and rf power imposed on 2-inch ZnO–Al2O3 (2 wt%) target,and their electrical and structural properties together with the corresponding etching behavior in 0.5%HCl solution were examined. The effect of rf power on the electrical and structural properties of AZO films was marginal, but in the case of working Ar gas pressure and substrate temperature, substantial variations in the electrical and structural properties were observed. The optimum electrical properties were obtained for AZO film deposited at 150 ℃ in lowest working pressure of 1.2 mTorr. The behavior of crater formation upon etching varied significantly depending on the structure of the film, and it was shown that the etching rate could be expressed in inversely proportional function of the crystallinity represented as (002) peak intensity. Also, for films with similar crystallinity, i.e. (002) peak intensity, dense structured film deposited at high temperature had much lower etching rate than open structured films deposited under high working Ar gas pressure.

천맥탕(天麥湯)이 항알러지 염증반응에 미치는 영향

김용현,이승연,김원일,Kim, Yong-Hyeon,Lee, Seung-Yeon,Kim, Won-Il 대한한방소아과학회 2008 대한한방소아과학회지 Vol.22 No.1

Objectives The purpose of this study was to examine the anti allergic reaction with Cheonmaec-tang. Methods We examined Cell Viability, ${\beta}$-hexosaminidase, TNF-${\alpha}$, IL-4 secretion from RBL-2H3 cell after pretreatment with 2 ㎎/ml, 4 ㎎/ml of Cheonmaec-tang. Results We observed that Cheonmaec-tang is reduced to ${\beta}$-hexosaminidase, TNF-${\alpha}$, IL-4 secretion in RBL-2H3 cell. Conclusions These results indicate that Cheonmaec-tang has anti-histamic effect and controls TNF-${\alpha}$, IL-4 secretion on allergic reaction.

폴리머용액법 및 알루미나 seed를 도입한 YAG:Ce³⁺ 형광체 분말 합성

김용현,이상진,Kim, Yong-Hyeon,Lee, Sang-Jin 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.1

$YAG:Ce^{3+}$ phosphor powders were synthesized using a $Al_2O_3$ seed (average particle size: 5 ${\mu}m$) by the polymer solution route. PVA solution was added to the sol precursors consisting of the seed powder and metal nitrate salts for homogeneous mixing in atomic scale. All dried precursor gels were calcined at $500^{\circ}C$ and then heated at $1400^{\circ}C{\sim}1500^{\circ}C$ in $N_2/H_2$ atmosphere. The final powders were characterized by using XRD, SEM, PSA, PL and PKG test. All synthesized powders were crystallized to YAG phase without intermediate phases of YAM or YAP. The phosphor properties and morphologies of the synthesized powders were strongly dependent on the PVA content. Finally, the synthesized $YAG:Ce^{3+}$ phosphor powder heated at $1500^{\circ}C$, which is prepared from 12:1 PVA content and has an average particle size of 15 ${\mu}m$, showed similar phosphor properties to a commercial phosphor powder.

천맥탕(天麥湯)의 알레르기 염증반응 및 기전탐색에 관한 연구

김용현,이승연,김원일,Kim, Yong-Hyeon,Lee, Seung-Yeon,Kim, Won-Il 대한한방소아과학회 2010 대한한방소아과학회지 Vol.24 No.1

Objectives The purpose of this study was to examine the pathway of anti-allergic effects of Cheonmaec-tang (CMT). Methods We examined the cell viability, $\beta$-hexosaminidase release, pro-inflammatory cytokines secretion and mRNA expressions, nuclear factor-kappa B (NF-${\kappa}B$) (p65) activation, inbibitor kappa B-alpha ($I{\kappa}B-{\alpha}$) degradation, and MAPKs activation in RBL-2H3 cells pre-treated by CMT of 2.0 mg/ml, 4.0 mg/ml separately. Results We observed that CMT reduced the secretion of $\beta$-hexosaminidase, TNF-$\alpha$, IL-4 and the expression of COX-2 mRNA in RBL-2H3 cells. Furthermore, CMT inhibited the levels of activation of NF-${\kappa}B$ (p65) protein, ERK MAPK, and degradation of $I{\kappa}B-{\alpha}$ in RBL-2H3 cells. Conclusions These results show that CMT has an anti-histamine effect and inhibitory effect of NF-${\kappa}B$ (p65) through regulation of $I{\kappa}B-{\alpha}$ degradation. These suggest that CMT could be used as an anti-allergic medicine.

유도무기 획득단가 추정 모델 개발에 관한 연구

김용현,이용복,정원일,김동규,강성진,Kim, Yonghyun,Lee, Yongbok,Jung, Wonil,Kim, Dongkyu,Kang, Sungjin 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.5

Cost estimates are necessary for government acquisition program to support decisions about funding, to develop annual budget requests and to validate resource requirements at key decision points. Many researches have been done about cost estimating technique recently. Parametric cost estimating models based on CERs(Cost Estimating Relationships) have been mainly used using regression method with historical data. However, there are many restrictions in developing Korean version CERs because the number of data points are too small. Specially, data collection and data management system are unstable in Korean defense environment, when developing CERs. In this research, we analyzed the historical data, and found some cost drivers in guided weapon system area. We developed the Acquisition Unit Cost CER using the regression to remove multicollinearity in the historical data. So we could overcome the restriction of the insufficient sample number. This research as a first attempt is meaningful in terms of obtaining our own Acquisition Unit Cost CER using historical cost and physical characteristic in Korean development environment.

The Tensile Properties and Wear Behavior of Mixing-reinforced Composites by Squeeze Casting Process

김용현,이광학,Kim, Yong-Hyeon,Lee, Gwang-Hak Materials Research Society of Korea 1999 한국재료학회지 Vol.9 No.4

The tensile strength and water resistance of ADC12 alloy matrix composites reinforced with saffil/ceraklwool and saffil/Si particle prepared by squeeze casting have been investigated in room temperature and $250^{\circ}C$. Adhesive and scuffing wear phenomena was studied when load was changed to 10~40N and wear velocity was 2.0m/s at room temperature and $250^{\circ}C$. Generally, the morphology of tensile fractured surface revealed dimple pattern which implies ductile fracture of the composites. However, cleavage fracture was also observed in case of ADC12 alloy based saffil/Si particle composite. The maximum tensile strength of 320MPa was obtained in ADC12 alloy based composites reinforced by saffil/cerakwool(5:5) preformed fibers. In the results of dry wear test, it was observed that scuffing was occurred at 40N in room temperature and 30N for $250^{\circ}C$.

선박엔진용 P-V 주철의 내마모성에 관한 연구

김용현,김대영,이광학 ( Yong Hyun Kim,Dae Young Kim,Kwang Hak Lee ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.3

N/A In thia study, wear resistance of P-V cast iron which is used as a material of cylinder liner for marine engine was investigated. Wear test was conducted by the wear test machine of Suzuki type(EFM-III-E model, 5000N for load, 4.0㎧ for velocity, Japan). Adhesive and scuffing wear phenomena was studied when load was changed from 60N to 400N and wear velocity was 0.25㎧ at room temperature and 250℃. In the case of dry friction at room temperature, scuffing phenomena of wear test specimens without vanadium was occurred at 400N, specimens with vanadium at the 400N was observed only adhesive wear phenomena. In the case of dry friction at 250℃, scuffing phenomena was observed at 180N for wear specimens without vanadium and 240N for wear specimens with vanadium.

좌제기제가 아스피린 좌제의 생체내이용율에 미치는 영향

김용현,이진환,최준식,Kim, Yong-Hyun,Lee, Jin-Hwan,Choi, Jun-Shik 한국약제학회 1988 Journal of Pharmaceutical Investigation Vol.18 No.2

The influence of different suppository bases on the dissolution, and the bioavailability of aspirin suppositories in rabbits and humans was investigated using Witepsol H15 (WIT), WIT-Tween 80 (TWE), WIT-sodium lauryl sulfate (SLS), polyethylene glycol (PEG), hollow WIT (WIT-HOLL) and capsule incorporated into WIT (WIT-CAP). The results obtained were as follows: 1) Dissolution rates of aspirin suppositories with different bases in distilled water were faster in the order of WIT-TWE >WIT-SLS >PEG >WIT-HOLL >WIT >WIT-CAP. 2) The maximum blood levels $(C_{max})$ of aspirin in rabbits and humans were highest in WIT-TWE and WIT-SLS bases, but $C_{max}$ from WIT base was lower than that in oral administration of aspirin suspension. 3) The times reaching the maximum blood levels $(T_{max})$ in rabbits were 1 hr for oral administration, 1.5-2.5 hr for WIT-TWE, WIT-SLS, PEG, and WIT bases, and 2.5-4.0 hr for WIT-HOLL and WIT-CAP bases, but $T_{max}$ in humans were 1 hr for oral administration and WIT-TWE base, and 2-4 hr for WIT and WIT-HOLL bases. 4) Relative bioavailability (RBA) of aspirin suppositories in rabbits was higher in WIT-SLS, WIT-TWE and PEG bases than that in oral administration, and RBA of aspirin suppositories in humans was higher in the order of WIT-TWE >PEG >WIT-HOLL >oral >WIT bases tested. 5) Good correlation between dissolution rates and $C_{max}$ was obtained: y = 0.60x+32.23 (r = 0.96) for rabbits, and y = 0.60x+35.74 (r = 0.97) for humans.

증례 : 혈액종양 ; 소화기계 및 호흡기계에 발생한 이시성 4중복암

김용현 ( Yong Hyun Kim ),박건우 ( Keon Woo Park ),이순일 ( Soon Il Lee ),임도형 ( Do Hyoung Lim ),이현숙 ( Hyun Suk Lee ),현경희 ( Kyung Hee Hyun ) 대한내과학회 2012 대한내과학회지 Vol.82 No.1

한 사람에서 다발성으로 악성종양이 발생하는 다발 원발암은 1889년 Billroth에 의해 처음 발표되었다. 최근 들어 악성종양에 대한 점진적인 진단 및 치료기술의 발달로 다발 원발암의 발생률은 증가되는 추세이다. 국내에서도 3중복암에 대한 몇몇 증례 보고가 있었으나 4중복암에 대한 발표는 드물다. 최근 저자들은 69세 남자에게서 발생한 이시성 4중 복암-폐, 식도, 성문, 하인두-을 경험하였기에 문헌고찰과 함께 보고하는 바이다. Multiple primary neoplasms, defined as the occurrence of multiple malignant neoplasms in the same individual, were first reported by Billroth in 1889. With gradual improvements in diagnostics, and the early detection and effective treatment of malignant neoplasms, the prevalence of multiple primary neoplasms seems to be increasing. Although there have been several reports of triple primary neoplasms in Korea, cases of quadruple neoplasms are rare. Recently, we diagnosed a 69-year-old male with primary neoplasms in the Lung, esophagus, vocal cords, and hypopharynx. The authors report this rare case of four metachronous primary neoplasms and provide a review of the Literature. (Korean J Med 2012;82:110-114)