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포타슘 술포네이트 폴리스타이렌 아이오노머의 기계적인 성질에 미치는 Crown ether의 영향
나연화,조규성,이법원,김준섭,유지강,박기주 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.1
The effects of crown ether on the dynamic mechanical properties of potassium sulfonated polystyrene ionomer were investigated. As expected, it was found that when crown ether molecules were added to the ionomer, the crown ether molecules interacted with K^(+) cations and weakened the ionic interaction between K^(+)/sulfonate ion pairs of the ionomer significantly. Thus, no multiplets were present, and, in turn, no clustering was found. When the ether was added to interact with 50% of K^(+) cations, weak clustering was observed: the clustering was slightly stronger than that of a 50% neutralized ionomer. From this result, it was speculated that in the 50% neutralized sample H^(+) ⇔ K^(+) cation exchange occurs rapidly between -SO₃H and -S0₃K groups in multiplets. which weakens ionic interactions. In the 50% crown ether-added sample, however, -S0₃- group, instead of -S0₃H, is present, and thus no cation exchange is expected to occur.
폴리(스타이렌-b-아이소부틸렌-b-스타이렌) 삼블록 공중합체 아이오노머의 기계적인 성질
나연화,김희석,김준섭,유지강,박기주,이영관 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.2
The dynamic mechanical properties of poly(styrene-b-isobutylene-b-styrene) and its sulfonated ionomers were investigated. The triblock copolymer showed a tan δ peak at ca. -25℃, which is ascribed to the T_(g) of polyisobutylene blocks. The copolymer also showed a shoulder on a tan δ curve at ca. 50℃, which is probably associated with crystallization and/or melting of the crystalline polyisobutylene blocks. Above 100℃, the copolymer started to flow. In the cases of ionomers, well developed rubbery plateaus, extended to ca. 150-160℃, were seen in modulus-temperature plots. A tan δ peak for the T_(g) of the polyisobutylene blocks and a shoulder peak were also observed for the tetramethylammonia neutralized sulfonated ionomer. However, the shoulder peak became smaller and shifted to low temperatures, which implies that the ionic interactions in this system reduces the ability of crystallization or/and melting of the polyisobutylene blocks. For the K neutralized ionomer sample, only a tanδ peak for the T_(g) of the isobutylene blocks was seen. This different result in these two ionomers is believed to be due to the difference in the strength of ionic interactions.
Styrene-co-lithium methacrylate ionomer의 기계적인 성질에 미치는 LiCl의 영향
나연화,김준섭,유지강,박기주 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.2
The effect of LiCl salt added to styrene-co-lithium methacrylate ionomer on the mechanical properties of ionomers was studied dynamic rnschanically. When the LiCl salt was added to a 100% Li-neutralized ionomer, the amount of added salt. in the range of 100-300% to ionic groups of the ionomer, did not change the mechanical properties of the ionomers, This implies that the added salt may form isolated LiCl salt aggregates in the polymer matrix. However, when LiCl was added to a 200% neutralized ionomer, the cluster T_(g) shifted to a low temperature and then the sample started to flow. This result suggests that in this case the LiCl salts reside in and near the multiplets, resulting the weakening of ionic interactions between ionic groups in multiplets.
카복실레이트 유기염을 포함하고 있는 폴리(스타이렌-co-메타크릴레이트) 아이오노머의 성질
나연화,윤두수,이법원,김준섭,최재곤,유지강 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.1
The dynamic mechanical properties of polyfstyrene-co-sodium methacrylate) ionomer (3.4 mol% of ions) blended with three low-molecular-weight carboxylate organic salts. i.e. sodium benzoate, sodium isophthalata, and sodium benzenetetrabenzoate, were studied. When organic salts were added to ionomers to make 1:1 and 1:2 ratio of mole of caboxylate groups of ionomer/organic salts, it was found that the ionic modulus increased, but that cluster Tg shifted to lower temperature. Thus, it was suggested that part of organic salts participate in the multiplets with ionic groups of the ionomer, resulting in lowering cluster Tg, and that the rest of salts reside in matrix and form ionic aggregates, which act as filler. However. in a 1:8 blend, very weak clustering was found. This means that the ionic groups of ionomer start to form ionic aggregates with any ionic groups in their proximity; thus the number density of chains surrounding multiplets drops drastically, esulting in a very small amount of clusters.
나연화(Yeon Hwa La),신병식(Byoung Shick Shin),박영하(Young Hwa Park),금형용(Hyung Yong Keum),김종철(Zong Chul Kim),이동욱(Dong Ook Lee),정우철(Woo Chuel Jung),이성원(Sung Won Lee),조용(Yong Cho),노의선(Eu Sun Ro) 대한산부인과학회 2001 Obstetrics & Gynecology Science Vol.44 No.11
Trisomy 18, called Edward syndrome, occurs in about 3500-8000 births. It is much more common at conception, with about 95% of cases resulting in spontaneous abortion or stillbirth. Postnatal survival is poor, with the majority of patients dying in early infancy. Characteristic findings include cardiac malformations, mental retardation, growth retardation, a prominent occiput, micrognathia, clenched hands, and rocker-bottom feet, omphalocele. The prenatal sonographic findings of our case include delayed growth, omphalocele, wrist joint fixation, choroid plexus cyst, hydramnios and postnatal gross findings include growth retardation, omphalocele, wirst joint fixation, absence of radius, syndactyly, focal absence of phalanges and flexion deformities of fingers and toes. We report a case of prenatally diagnosed Edward syndrome, which is confirmed by chromosome analysis, with brief review of related literatures.
유채로부터 갓으로 유전자이동에 의한 교잡종의 휴면에 따른 잡초화 가능성
임연화,육민정,장전걸,나경주,박수형,김도순 한국잔디학회 2015 Weed & Turfgrass Science Vol.4 No.1
To assess the dormancy associated weedy risk of the F1 hybrid generated by hybridization between Brassica juncea(maternal) and Brassica napus (paternal), seed germination, dormancy and longevity were examined sequentially after seedharvest. The F1 hybrids exhibited the intermediate characteristics of their parents in seed germination and dormancy withrelatively high dormancy rate of 41.1%. In summer, F1 hybrid seeds buried in the 3 cm soil exhibited greater viability (52.4%) thanthose in the soil surface with greater seed longevity (74.6%) than its maternal (63.3%) and paternal (33.7%) parents at 100 days ofover-summering in soil. In winter, F1 seeds buried in the soil surface were more viable than those in the 3 cm soil with greater seedlongevity (83.5%) than its maternal (39.0%) and paternal (71.7%) parents at 100 days of over-wintering in soil. Therefore, it isconcluded that F1 hybrid resulted from gene flow from OSR to mustard has high seed dormancy and longevity during summerand winter, suggesting its weedy risk potential. Further studies are required to examine the reproductivity and fitness cost of F1hybrid to make a clearer conclusion of its weedy risk. 본 연구는 유채의 화분이동으로 근연종 갓과의 교잡을통해 형성된 교잡종의 발아휴면특성과 월하 및 월동성을 평가하여 교잡종의 잡초화 가능성을 예측하고자 본 연구를 수행하였다. 교잡종은 부본인 유채와 모본인 갓에 비해전반적인 발아특성이 갓에 근접한 중간적인 특성을 보여주었으며, 휴면성도 41.1%로 갓에 근접한 높은 휴면성을보여주었다. 수확 직후 종자를 토양에 매립하여 월하특성을 평가한 결과 표토보다는 3 cm 토심에서 월등히 높은 월하특성을 보여주었으며, 월하기간과 상관없이 3 cm 토심조건에서 부본인 유채에 비해 매우 높고 모본인 갓에 비해약간 높은 월하특성을 보여주었다. 반면 종자의 월동특성은 월하특성과 반대로 표토조건에서 교잡종이 부모종보다높은 월동성을 가지는 것으로 확인되었다. 따라서 유채-갓교잡종은 휴면성이 비교적 높고 월하 및 월동성이 높아 잡초화 가능성이 있음을 시사한다. 유채-갓 교잡종의 보다 명확한 잡초화 가능성 평가를 위해서는 교잡종의 종자생산가능성 및 자연 생태계 적응성 여부에 대한 추가적인 연구가 필요하다.