• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.45-52
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• 2010

Two different imide oligomers(6FDA-ODA/APA and 6FDA-MDA/MA) having crosslinkable end groups were prepared by using a solution imidization method and their properties were investigated. Also, semi-interpenetrating polymer networks(semi-IPN) were prepared using the blends of imide oligomers with polyetherimide $Ultem^{(R)}$, which is used in dual-ovenable packaging materials. The characteristic properties of semi-IPN films were interpreted by using TGA, Thin Film Diffusion Analyzer, and WAXD. Molecular weights of imide oligomers were successfully controlled utilizing 2-aminophenylacetylene(APA) and maleic anhydride(MA) as an endcapping agent. Exotherm reactions by crosslinking appeared and the amount of exthotherm heat was linearly increased as the content of imide oligomers was increased. For semi-IPNs of $Ultem^{(R)}$ and imide oligomers, 5% and 10% weight loss temperatures increased as the contents of imide oligomers were increased. Diffusion coefficient and water uptake of semi-IPNs decreased as the content of imide oligomers was increased, which might be resulted from hydrophobic fluorine group and high packing density. It was concluded that relatively low thermal stability and hydrolytic stability of polyetherimide $Ultem^{(R)}$ were improved by incorporating new developed imide oligomers.

• Polymer(Korea)
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• v.38 no.4
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• pp.510-517
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• 2014

A series of polyimide (PI) was prepared by reacting 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) as the anhydride and bis(3-aminophenyl) sulfone (APS), bis[4-(3-aminophenoxy)-phenyl] sulfone (BAPS), 2,2-bis(4-aminophenyl)-hexafluoropropane (6FPD), 2,2-bis[4-(4-aminophenoxy)-phenyl]hexafluoropropane (6FBAPP), 2,2'-bis(trifluoromethyl)benzidine (TFDB), or 1,4-phenylenediamine (PDA) as the diamine. Residual stress behaviors were detected in-situ during thermal imidization of the polyimide precursors using a thin film stress analyzer (TFSA), and interpreted with respect to their morphology. According to the molecular orientation and packing order, the residual stress varied from 23.1 to 12.5 MPa, decreased with increasing chain rigidity. The thermal properties of the PI films were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA). Their optical properties were measured by ultraviolet-visible spectrophotometer (UV-vis), and spectrophotometry. The properties of PI films were found to be strongly dependent upon the morphological structure. However, trade-offs between residual stress and optical properties were identified.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.31-36
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• 1977

The monthly distribution of marine bacteria in the coastal waters of Chung-Mu was investigated from April, 1976 to March, 1977. The aim of this study was to obtain basic data for the prevention of food poisoning and for the efficient aquaculture of the area. Samples of sea water, mud, fish and shell fish were taken every month. The results are as follows: 1. One thousand four hundred and twenty-six strains were isolated from 732 samples of sea water, mud, fish and shell fish. They were 450 strains of Pseudomonas fluorescens, 422 strains of Achromobacter liquefacience, 72 strains of Vibrio parahaemolyticus, 234 strain of Vibrio alginolyticus, and 248 strains of Proteus vulgaris. 2. V. parahaemolyticus occupied $9.84\%$ of the total samples and $52\%$ of them were found in the sea water and mud. 3. The muds sampled districtly beneath the aquaculture raft contained much gas. They seemed to originate from the deposition of excretion of shell fish. The fatness of the shell fish was low where the gas was abundant. 4. It was .found that the shell fish with low fatness contained much Vibrio sp. 5. Regional distribution shows that marine bacteria were abundant in the order of station 10, 9, 8, 11, 1. The area around station 9 was polluted by reclamation of the area, and station 8 showed the influence of the excrement treat tank located nearly.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.320-326
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• 2013

In this study, various polyimide films were synthesized via low temperature cure in order to understand changes in their physical properties when using 4,4'-oxydianiline (ODA) as a diamine and dianhydride molecules with different backbones on a single diamine such as 4,4'-Oxydiphthalic anhydride (ODPA), 4,4-hexafluoroisopropylidene diphthalic dianhydride (6FDA), and 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA). After the synthesis of poly(amic acid), polyimide films were fabricated by adding 1,4-diazabicyclo [2.2.2]octane (DABCO), a low-temperature catalyst, at various wt% to poly(amic acid)s. Changes of optical and thermal properties were compared and analyzed between polyimide films without catalyst and polyimide films with catalyst by FT-IR, UV-Vis transmittance, DSC/TGA, and WAXD analysis. Wide-angle X-ray diffraction (WAXD) analysis revealed that the mean intermolecular distance decreased with the use of a catalyst by the type of dianhydride. Thus, while the optical properties of the films improve by a low-temperature cure performed using a catalyst, their thermal properties decrease. These changes can be explained by the changes in the morphological structure of the films triggered by a catalyst-induced reduction in the mean intermolecular distance. Moreover, the results show that the type of dianhydride determines the degree of change in the optical and thermal properties in each types of polyimide, demonstrating that changes in the optical and thermal properties are directly associated with the backbone of the polyimide structure.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.43-53
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• 2015

This study analyzes economic feasibility of the LED lighting system compare to the halogen. To evaluate economic feasibility of the LED devices, we analyzed the size of theater, current value of the lighting devices in kinds, annual cost and annual cost according to the surface in case of designing stage lighting system with LED using WEELS 2011. Also, to compare energy consumption, we analyzed consumption and amount of electric energy by the surface and the amount of CO2 emission. Data showed that annual cost of the LED devices are highly inexpensive than halogen and now the value is of great. However initial cost of the equipment 200% higher than halogen. Though LED devices are expensive in startup setting, the value of utilization factor is large and depreciation years of LED(30years) are longer than halogen(2years). Therefore, annual cost of LED can make up the minus. Consider the tendency of reducing price of LED devices, we can assume that annual cost of the LED will be lower than halogen devices. Further, in 3years the expense of LED and halogen is reversed.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.181-188
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• 2009

Pt catalyst was adsorbed on Carbon nanofiber (CNF) by modified polyol method after acid treatment of the carbon support with $HNO_3$ and $H_{2}SO_{4}$. As the time for acid treatment increases, more oxygen functional groups on carbon surface were produced which improve the loading amount and dispersion of Pt catalyst on carbon supports. In order to inspect the effect of CNF acid treatment time on electrochemical corrosion, constant potential of 1.4 V was applied to a single cell for 30 min and the amount of $CO_2$ emitted was monitored with on-line mass spectrometry. According to the results of our experiment, more $CO_2$ was produced with Pt/ oxidized-CNF catalyst in compared to that with unoxidized-CNF. Increasing acid treatment time also induces the more $CO_2$ emission. Besides, performance degradation after corrosion test expanded with severer carbon corrosion. From the observed results, it can be concluded that the acid treatment of CNF is beneficial to catalyst loading, but it also is a significant factor declining the fuel cell durability by accelerating electrochemical oxidation of carbon support.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.621-627
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• 2013

In order to apply eco-friendly poly(propylene carbonate) (PPC) into barrier packaging materials, six different PPC/exfoliated graphite (EFG) nanocomposite films with different EFG were successfully prepared by a solution blending method. Their water sorption behavior was gravimetrically investigated as a function of the EFG content and interpreted with respect to their chemical structure and morphology. The water sorption isotherms were reasonably well fitted by Fickian diffusion model, regardless of morphological heterogeneities. With increasing the EFG content, the diffusion coefficient and water uptake decreased from $12.5{\times}10^{-10}cm^2sec^{-1}$ to $7.2{\times}10^{-10}cm^2sec^{-1}$ and from 8.9 wt% to 4.2 wt%, respectively, which indicates that the moisture resistance capacity of PPC was greatly enhanced by incorporating EFG into PPC. The enhanced water barrier property of the PPC/EFG nanocomposite films with the high aspect ratio EFG makes them potential candidates for versatile packaging applications. However, to maximize the performance of the nanocomposite films, further researches are required to increase the compatibility of EFG in the PPC matrix.

• Journal of Korean Medical classics
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• v.13 no.1
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• pp.146-183
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• 2000

통과이상적연구(通過以上的硏究), 장상한학술적성숙기(將傷寒學術的成熟期), 칙지명대여청대관여상한의학사적내용정리(則至明代與淸代關與傷寒醫學史的內容整理) 여하(如下). 1. 명청시대적시대배경사상한학적내용갱풍부(明淸時代的時代背景使傷寒學的內容更豊富), 촉진상한학술적발전(促進傷寒學術的發展) 병차출현료흔다관여상한적저작(幷且出現了?多關與傷寒的著作), 단실제상야출현료상한론내용적중복여지론술일반부분(但實際上也出現了傷寒論內容的重複與只論述一般部分), 혹저자립안조잡적처방지폐단(或著者立案粗雜的處方之弊端). 차기우출현각종상한학파적리유(此期又出現各種傷寒學派的理由), 시인위당시류행적사조(是因爲當時流行的思潮), 칙정주리학적영향여명대문단부고(則程朱理學的影響與明代文壇復古), 의고적추향(擬古的趨向), 환유금원시대적백가쟁오등(還有金元時代的百家爭嗚等), 성료형성상한학파적기초(成了形成傷寒學派的基礎). 2. 위료불실거상한론적본래의식(爲了不失去傷寒論的本來意識), 주장정리화고정원문회부왕숙화이전모양적착간중정파시왕안도기료개단(主張整理和考訂原文恢復王叔和以前模樣的錯簡重訂派是王安道起了開端), 방유집확대료기의식(方有執擴大了其意識). 유창여침명종시대표저학파학자(喩昌與沈明宗是代表這學派學者), 장로(張?) 정응모(程應?) 주양준(周揚俊) 오겸등수료저학설(吳謙等隨了這學說). 3. 주장(主張)'존왕(尊王)(숙화(叔和))찬성(贊成)(무기(无己))'적유호구론파(的維護舊論派), 주장료불능수변개상한론삼음삼양편적배렬여순서(主張了不能隨變改傷寒論三陰三陽篇的排列與順序), 문자(文字), 구문(句文), 문장(文章), 고세식(高世?), 진념조등인(陳念祖等人). 4. 주장상한론적정수재어변증론치(主張傷寒論的精髓在於辨證論治), 선우운용칙능득상한핵심리론적학파시변증론치학파(善于運用則能得傷寒核心理論的學派是辨證論治學派). 저학파분사개계통(這學派分四?系統), 이처방수집증상적의가유허굉(以處方收集證狀的醫家有許宏), 가금(柯琴), 서대춘(徐大椿); 이치법수집증상적의가유오인구(以治法收集證狀的醫家有吳人駒), 우이(尤怡); 이분유륙경찰증상적의가유진념조(以分有六經察證狀的醫家有陳念祖), 포성(包誠); 이증상분류증후적의가유류순(以證狀分類證候的醫家有劉純), 왕긍당(王肯堂), 진지정(秦之楨), 침금오등인(沈金鰲等人). 5. 회통파유량종류형(?通派有兩種類型), 일시수통상한여온병적학파(一是誰通傷寒與溫病的學派), 간칭회통파(簡稱?通派), 대표의가유도화(代表醫家有陶華), 오정(吳貞), 유근초등인(兪根初等人), 령일개유회통중의여서의적립장상해석상한적의가당종해(?一?有?通中醫與西醫的立場上解釋傷寒的醫家唐宗海). 6. 경전학파시이상한론위보귀적경전래인식(經典學派是以傷寒論爲保貴的經典來認識), 병차지유숭상차경여사상적학파(幷且持有崇尙此經與思想的學派), 차리분량개편우원문적고증래연구적경전고증파(此里分兩?偏于原文的考證來硏究的經典考證派), 화인위지유상한론(和認爲只有傷寒論), 재능총괄치료외감병(才能總括治療外感病), 부정온병학설병배척적경전림상파(否定溫病學說幷排斥的經典臨床派).

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.305-312
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• 2005

Poly(urethane-imide)s were prepared by reaction between crosslinkable endgroup containing soluble polyimide (PI) by chemical imidization and acrylate end-capped polyurethane (PU). Poly (amic acid) was prepared from 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 4,4'-oxydianiline (ODA) and then end-capped with maleic anhydride (MA). The PU prepolymers were prepared by the reaction of polycaprolactone diol, tolylene 2,4-diisocyanate and end-capped with hydroxyl ethyl acrylate. The effect of PU content on the residual stress behavior, morphology and thermal property was studied. The poly(urethane-imide)s were characterized by thin film stress analyzer (TFSA), XRD, TGA and DMTA. Low residual stress and slope in cooling curve were achieved by higher PU content. Compared to typical polyurethane, these polymers exhibited better thermal stability due to the presence of the imide groups. Finally the residual stress of poly(urethane-imide)s was strongly affected by the morphological structure.

• Polymer(Korea)
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• v.38 no.6
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• pp.752-759
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• 2014

Crosslinked polyimides (PIs) were synthesized by reacting 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) and 2,2'-bis(trifluoromethyl)benzidine (TFDB) with various ratios of the cross-linkable, end-capping agent cis-1,2,3,6-tetrahydrophthalic anhydride (CDBA) via ring-opening metathesis polymerization. Residual stress behaviors were investigated in-situ during thermal imidization of the crosslinked PI precursors using a thin film stress analyzer (TFSA) by wafer bending method. The thermal properties were investigated via differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and thermogravimetric analysis (TGA). The optical properties were measured by ultraviolet-visible spectrophotometer (UV-vis) and spectrophotometry. All properties were interpreted with respect to their morphology of crosslinked networks. With increasing the amounts of the end-capping agent, the residual stress decreased from 27.9 to -1.3 MPa, exhibited ultra-low stress and high thermal properties. The minimized residual stress and enhanced thermal properties of the crosslinked PI makes them potential candidates for versatile high-density multi-layer structure applications.