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Gwang-Mook Choi(최광묵),Jin-Ju Choi(최진주),Woo-Cheol Kim(김우철),Hwanmin Hwang(황환민),Myungwoong Kim(김명웅),Min-Jun Kim(김민준) 한국고분자학회 2021 폴리머 Vol.45 No.6
본 연구에서는 나트륨-알지네이트/폴리아크릴아마이드(SA/PAM) 하이드로겔의 온도 및 가교제로 작용하는 N,N′-메틸렌비스아크릴아마이드(MBAAm) 농도에 따른 수용 형태 및 시간 변화를 분석하였다. 실험 결과, 수온이 증가하거나 가교제 농도가 감소할수록 SA/PAM 하이드로겔의 팽윤 및 수용 속도가 증가함을 확인하였다. 수온 상승 시 이온결합이 불안정하고 아마이드 결합이 깨지면서 하이드로겔의 수용 속도를 증가시키는 반면, MBAAm의 밀도 감소 시에는 주요 결합력인 이온결합력이 약화되어 고온수에 취약함을 확인하였다. 본 연구를 통해 SA/PAM 하이드로겔의 수용속도의 제어가 가능함을 증명하였고 선택적 수용이 가능한 차수재로서의 가능성을 제시하였다. The objective of this study was to examine changes in the dissolution rate of sodium-alginate/polyacrylamide (SA/PAM) hydrogel according to water temperature and concentration of cross-linking agent N,N"-methylenebisacrylamide (MBAAm). Results confirmed that swelling and dissolution rates of the SA/PAM hydrogel were increased when the temperature of the water was increased or the amount of MBAAm was decreased. When water temperature was increased, ionic crosslinks became unstable and amide bonds were broken due to hydrolysis, causing the hydrogel to rapidly dissolve in the hot water. Also, after the amount of MBAAm was decreased, ionic crosslinks became dominant and SA/PAM hydrogel became more vulnerable to hot water. Here, we analyzed the dissolution rate of hydrogel following temperature and MBAAm density changes. We also developed a selectively dissolvable water-blocking hydrogel that could be stable in cold water and become dissolved quickly in hot water.
PEDOT:PSS/Polyacrylamide Nanoweb: Highly Reliable Soft Conductors with Swelling Resistance
Choi, Gwang Mook,Lim, Seung-Min,Lee, Yoo-Yong,Yi, Seol-Min,Lee, Young-Joo,Sun, Jeong-Yun,Joo, Young-Chang American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.10
<P>According to the recent growth in interest of human-friendly devices, soft conductors, which are conductive materials with an inherent compliance, must have a low electrical strain sensitivity under large deformation conditions, environmental stability in water, and reliability even for complex and repeated deformation, as well as nontoxic characteristics. In this study, we fabricated a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/polyacrylamide nanoweb that satisfies all of the above requirements through a web microstructure with entangled conductive nanofibers. Since the web structure can be deformed through structural alignment, the conductive path is stably maintained during deformation, which makes it highly conductive, electrically stable, and electrically strain insensitive. The tangled nanofibers are composed of PEDOT:PSS as a conductive component and polyacrylamide as a binding material, so it is nontoxic and has the soft properties of the material itself, which can withstand large deformations. Additionally, the material has a good electrical stability against repeated deformation so that the resistance increased by only 13% after a 50% strain was repeated 1000 times. Notably, electrical instabilities such as noise and hysteresis were not evident during the repeated deformations. Finally, the nanoweb has excellent swelling resistance and maintains its mechanical and electrical characteristics in water.</P> [FIG OMISSION]</BR>
최재묵(Jae Mook Choi),이성학(Sung Hak Lee),김일환(Il Hwan Kim),박지은(Jie Eun Park),김덕열(Deog Yeor Kim),노현정(Hyun Jung Noh),김택로(Taekrho Kim),최광도(Do-Gwang Choi),김영훈(Young Hoon Kim),김진완(Jin Wan Kim),장준환(Joon Hwan Jan 한국독성학회 2004 Toxicological Research Vol.20 No.2
Safety pharmacological properties of CJ-11555, an anti-cirrhotic agent, were investigated in experimental animals and in vitro test system. CJ-11555 had no effects on normal body temperature in rats, motor coordination, chemoshock induced by pentetrazol, electric shock induced by electric shocker and writhing syndromes in mice at dose levels of 100, 300 and 1,000 mg/kg. CJ-11555 inhibited intestinal activity and prolonged hexobarbital-induced sleeping time in mice at the dose level of 1,000 mg/kg. CJ-11555 affected on general activity and behaviour tests in SD rats, such as<br/> lacrimation, ptosis, piloerection, decreased body tone, abnormal dispersion within the cage, diarrhoea, red colored faeces, slight hypothermia and decreased grooming, at the dose level of 1,000mg/kg in rats. CJ-11555 was effected on cardiovascular and respiratory system in anesthetized beagle dogs, such as tachycardia, increase of mean blood pressure and decrease of PR interval, decrease of respiratory rate and minute volume, at dose levels of 10 and <br/> 30mg/kg. However, these effects were also observed in vehicle treated anesthetized beagle dogs. In in vitro experiments, CJ-<br/> 11555 inhibited agonists (histamine, acetyl-choline or BaCl2) induced contraction of isolated guinea-pig at the concentration of 30x10-6 M. CJ-11555 was weekly inhibited hERG channel current at concentrations of 10 and 30x10-6 M, and IC50 was estimated to be higher than 30x10-6 M. Based on these results, it was concluded that CJ-11555 affected on cardiovascular and respiratory system, general activity and behaviour and hexobarbital-induced sleeping time at the dose level of 1,000 mg/kg and contraction of the smooth muscle and hERG channel current at the concentration of 30x10-6 M.
최재묵(Jae-Mook Choi),이성학(Sung-Hak Lee),김일환(Il-Hwan Kim),박지은(Jie-Eun Park),김덕열(Deog-Yeor Kim),노현정(Hyun-Jung Noh),김택로(Taekrho Kim),최광도(Do-Gwang Choi),김영훈(Young-Hoon Kim),김진완(Jin-Wan Kim),장준환(Joon-Hwan Jan 한국독성학회 2004 Toxicological Research Vol.20 No.1
Safety pharmacological properties of CJ-11555, an anti-cirrhotic agent, were investigated in experimental animals and in vitro test system. CJ-11555 had no effects on normal body temperature in rats, motor coordination, chemoshock induced by pentetrazol, electric shock induced by electric shocker and writhing syndromes in mice at dose levels of 100, 300 and 1,000 mg/kg. CJ-11555 inhibited intestinal activity and prolonged hexobarbital-induced sleeping time in mice at the dose level of 1,000 mg/kg. CJ-11555 affected on general activity and behaviour tests in SD rats, such as lacrimation, ptosis, piloerection, decreased body tone, abnormal dispersion within the cage, diarrhoea, red colored faeces, slight hypothermia and decreased grooming, at the dose level of 1,000<br/> mg/kg in rats. CJ-11555 was effected on cardiovascular and respiratory system in anesthetized beagle dogs, such as tachycardia, increase of mean blood pressure and decrease of PR interval, decrease of respiratory rate and minute volume, at dose levels of 10 and 30 mg/kg. However, these effects were also observed in vehicle treated anesthetized beagle dogs. In in vitro experiments, CJ-11555 inhibited agonists (histamine, acetyl-choline or BaCl2) induced contraction of isolated guinea-pig at the concentration of 30×10-6 M. CJ-11555 was weekly inhibited hERG channel current at concentrations of 10 and 30×10-6 M, and IC50 was estimated to be higher than 30×10-6 M. Based on these results, it was concluded that CJ-11555 affected on cardiovascular and respiratory system, general activity and behaviour and hexobarbital-induced sleeping time at the dose level of 1,000 mg/kg and contraction of the smooth muscle and hERG channel current at the concentration of 30×10-6 M.
Al-Si계 합금의 분말 크기 및 조성에 따른 반사율 변화 특성
최광묵,채홍준,Choi, Gwang Mook,Chae, Hong Jun 한국분말재료학회 (*구 분말야금학회) 2019 한국분말재료학회지 (KPMI) Vol.26 No.1
In this study, the effects of powder size and composition on the reflectance of Al-Si based alloys are presented. First, the reflectance of Al-Si bulk and powder are analyzed to confirm the effect of powder size. Results show that the bulk has a higher reflectance than that of powder because the bulk has lower surface defects. In addition, the larger the particle size, the higher is the reflectance because the interparticle space decreases. Second, the effect of composition on the reflectance by the changing composition of Al-Si-Mg is confirmed. Consequently, the reflectance of the alloy decreases with the addition of Si and Mg because dendrite Si and $Mg_2Si$ are formed, and these have lower reflectance than pure Al. Finally, the reflectance of the alloy is due to the scattering of free electrons, which is closely related to electrical conductivity. Measurements of the electrical conductivity based on the composition of the Al-Si-Mg alloy confirm the same tendency as the reflectance.
김증기,최광묵,서혁,Kim, Jeung-Ki,Choi, Gwang-Mook,Seo, Hyeok 한국국방경영분석학회 2005 한국국방경영분석학회지 Vol.31 No.2
As more advanced and complicated equipments are introduced, effective operation and maintenance, along with acquisition of the equipments, commands more significance lately. In order to perform effective depot maintenance, the Republic of Korea Army is continually developing the concept, cycle and method for operating the depot maintenance. Not only the high-cost testing and maintenance equipments but the highly developed maintenance technologies are required for the depot maintenance of the latest weapon system. In order to have the depot maintenance capability, this paper provides the standard and procedure for estimating the development cost of the depot maintenance elements to be utilized in the depot maintenance elements development project.