Polyethylene Glycol과 Dextran이 포함된 고분자 수용액의 액-액 상평형

조정모,강춘형 전남대학교 촉매연구소 2000 觸媒硏究 論文集 Vol.21 No.-

The extraction using an aqueous two-phase polymer solution (ATPS) is a promising technique for separation of biologically active materials. Since ATPS contains mainly water, it provides a mild environment to the biological materials so that their biological activities can be preserved during the process. Among the factors that influence the phase behavior of ATPS, the molecular weight distributions(MWD) of the phase forming polymers have long been ignored. With special attention to the effects of MWD of the polymers, the liquid-liquid equilibrium(LLE) phase diagrams of ATPS containing polyethylene glycol(PEG) and dextrin(Dex) are experimentally determined using the gel permeation chromatography(GPC) and the polymer fractionation in the phase separation is observed. Namely, we observe that the MWDs of both polymers in the coexisting phases are different from each other as well as from the original distribution. Furthermore it is found that while the average molecular weight of Dex in the top phase decreases with the increase of the tie-line length(TLL), that of the bottom phase asymptotically approaches that of the original. The continuous dilution method is examined for the complete determination of the phase diagrams.

Dextran Microsphere의 제조 및 특성에 관한 연구

조정모,강춘형 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.3

Methacryloyl(MA) 그룹이 유도된 dextran(dex-MA)을 이용한 microsphere는 코팅, 인쇄, 의약 산업 등에 널리 활용되고 있다. 본 연구에서는 Dex-MA, polyethylene glycol(PEG) 등의 고분자와 물로 구성된 수용액의 고분자 액-액 상분리 현상을 이용하여 dextran(Dex) microsphere를 제조하였으며 이들의 제조에 미치는 영향과 특성에 대해 알아보았다. Dex-MA는 transesterification반응을 통해 제조되었으며, ^1H NMR, ^13C NMR, FT-IR, GPC 등을 이용하여 그 반응특성을 관찰하였다. MA그룹의 치환된 양(degree of substitution; DS)은 ^1H NMR의 피크 강도로부터 계산하였으며, 질량수지에 의한 계산값과 비교하였다. ATPS를 이용한 에멀젼법을 사용하여 microsphere를 제조하였으며, 이를 위해 필요한 25℃의 Dex-MA/PEG/물 계의 액-액 상평형 도표는 실험을 통하여 결정하였다. 본 연구에서는 에멀젼 법을 이용하여 직경이 7.7-38㎛인 microsphere를 재현성있게 제조할 수 있었다. 계산된 DS가 microsphere의 제조와 특성에 미치는 영향을 조사하였으며, 팽윤 특성은 질량법과 Blue-Dex 용액법를 사용하여 측정하였다. Dextran-based microspheres have become growingly attractive in the fields of surface coating, printing, pharmaceutical and other industrial applications. In an effort to prepare the dextran-based microspheres, methacryloyl(MA) groups were introduced into dextran(Dex-MA) molecules as a crosslinking functional group via the transesterification reaction. The resulting Dex-MA was characterized by use of ^1H NMR, ^13C NMR, FT-IR, and GPC. Degree of substitution(DS) of the MA groups in the glucopyranose ring of a dextran molecule was calculated from peak intensities of ^1H NMR spectrum and compared well with the calculated value. The aqueous two-phase polymer system(ATPS) emulsion, which consists of Dex-MA, PEG, and water, was used for preparation of the microspheres. To this purpose, the phase diagrams of several Dex-MA/PEG/water systems at 25℃ were constructed. Microparticles with a volume mean diameter from 7.7 to 38㎛ could be prepared in a reproducible way. The DS could be used to tailor the size, the initial water content, and the swelling property of the resulting microspheres. In addition, the swelling properties of the microspheres were measured by means of the blue-Dex solution method and the gravimetric method.

한국인의 수근관 증후군에서 정중신경 단면적 비의 유용성

조정모,김세주,박병규,윤준식,정진석,이규호 대한재활의학회 2009 Annals of Rehabilitation Medicine Vol.33 No.5

Objective: To examine the usefulness of ratio of maximal swelling to normal cross sectional area (CSA) of median nerve with ultrasound in patients with carpal tunnel syndrome (CTS) and healthy controls. Method: Patients with electrodiagnostically proven CTS underwent ultrasonography of the median nerve. The median nerve area was measured at three points (maximal swelling site, 2 cm proximal to maximal swelling site, 12 cm proximal to maximal swelling site) and compared to values from asymptomatic volunteers. Results: The ratio of maximal swelling site to 12 cm proximal was 1.34±0.14 in asymptomatic volunteers and 2.31±0.43 in patients presenting with CTS. The ratio of maximal swelling site to 12 cm proximal gave 73.7% sensitivity and 90.0% specificity. While using only median nerve area at the wrist resulted in 81.6% sensitivity and 70.0% specificity, depending on the cutoff value used. Conclusion: The ratio of maximal swelling site to proximal in patients with CTS is elevated as compared to asymptomatic controls. The ratio of maximal swelling site to 12 cm proximal has higher specificity to diagnose CTS, and may be superior to measuring median nerve area at the wrist alone. Objective: To examine the usefulness of ratio of maximal swelling to normal cross sectional area (CSA) of median nerve with ultrasound in patients with carpal tunnel syndrome (CTS) and healthy controls. Method: Patients with electrodiagnostically proven CTS underwent ultrasonography of the median nerve. The median nerve area was measured at three points (maximal swelling site, 2 cm proximal to maximal swelling site, 12 cm proximal to maximal swelling site) and compared to values from asymptomatic volunteers. Results: The ratio of maximal swelling site to 12 cm proximal was 1.34±0.14 in asymptomatic volunteers and 2.31±0.43 in patients presenting with CTS. The ratio of maximal swelling site to 12 cm proximal gave 73.7% sensitivity and 90.0% specificity. While using only median nerve area at the wrist resulted in 81.6% sensitivity and 70.0% specificity, depending on the cutoff value used. Conclusion: The ratio of maximal swelling site to proximal in patients with CTS is elevated as compared to asymptomatic controls. The ratio of maximal swelling site to 12 cm proximal has higher specificity to diagnose CTS, and may be superior to measuring median nerve area at the wrist alone.

2P-753 Hydrocracking of Heavy Residual Feedstock with High Dispersion of Asphaltene

조정모,박철우,( Nguyen Manh Tung ),( N. N. Thuy ),정진환,이철위 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.0

멀티캐스트 CoAP 보안을 위한 키 설정 기법

조정모,한상우,박창섭 한국융합보안학회 2017 융합보안 논문지 Vol.17 No.5

본 논문에서는 멀티캐스트 CoAP 보안 키 설정 기법을 제안한다. 멀티캐스트 CoAP에서 CoAP 클라이언트가 송신한 CoAP Request 메시지는 멀티캐스트로 CoAP 서버 그룹에게 전송되지만, 각각의 CoAP 서버가 송신한 CoAP Response 메시지는 유니캐스트로 클라이언트에게 전송된다. 따라서 CoAP Request 메시지는 그룹키로, 각각의 CoAP Response 메시지는 CoAP 서버와 CoAP 클라이언트 간의 개별키(유니캐스트 키)로 보호된다. 제안하는 프로토콜은 클라이언트와 서버가 최초 CoAP 메시지 교환 과정에서 ECDH를 이용하여 그룹키와 개별키를 설정하는 것이다. 제안 프로토콜은 DTLS Handshake를 대체할 수 있어 통신효율이 높고 확장성이 있으며, 개별키를 설정하기 때문에 종단간 보안을 지원할 수 있다. In this paper, we propose a key establishment scheme for multicast CoAP security. For multicast CoAP applications, a CoAP Request message from a CoAP client is sent to a group of CoAP servers while each CoAP server responds with a unicast CoAP Response message. In this case, the CoAP Request message should be secured with a group key common to both the CoAP client and servers, while a pairwise key(unicast key) should be employed to secure each CoAP Response message. In the proposed protocol, the CoAP client and the CoAP server establish the group key and the pairwise key using the ECDH in the initial CoAP message exchange process. The proposed protocol , which is highly efficient and scalable, can replace DTLS Handshake and it can support end-to-end security by setting pairwise keys.

촉매공정을 이용한 바이오매스의 그린 화합물 전환

조정모,서영종 한국공업화학회 2012 한국공업화학회 연구논문 초록집 Vol.2012 No.-

Reduction of Coke Formation in Slurry-Phase Hydrocracking

조정모,( Nguyen Manh Tung ),서필원,김성호,강기혁,박선영,서휘민,김규태 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Development of heavy hydrocarbon into toluene insoluble organic residue (TIOR; or coke) is not a favored reaction pathway in an upgrading process of petrolium residue. In many commercial catalytic hydrocrackers, a small amount of coke formation can cause a serious operating problem of clogging and unexpected instability due to its continuous accumulation on the process units including reactors. In general, a high hydrogen partial presssure or a low reaction temperature below 400C, which requires a high CAPEX and/or OPEX, is favored to reduce coke formation. In the presentation we will discuss the reaction behaviors of coke formation and an effective strategy to suppress the pathway to coke during the slurry-phase hydrocracking.

Dextran-based Hydrogel의 제조 및 특성에 관한 연구

조정모,노선균,강춘형 전남대학교 촉매연구소 2001 觸媒硏究 論文集 Vol.22 No.-

Due to their sensitivity to external condition, adjustable permeability and high water content, hydrogels have widespread applications in medical, pharmaceutical, biochemical and other industrial fields. In this work, the dextran-based hydrogel was prepared by derivatization of polysaccharide with methacryloyl groups followed by polymerization of an aqueous solution of this methacrylated dextral(dex-MA) in presence of an initiator system consisting of potassium peroxydisulfate(KPS ) and N,N,N',N'-tetramethylethylene diamine(TEMED). The hydrogel and dex-MA thus prepared were characterized by 1H NMR, 13C NMR, FT-IR, and gel permeation chromatography(GPC). Degrees of substitution of MA groups in the glucopyranosyl ring(DS) estimated from peak intensities in 1H NMR spectra were found to be comparable with the prescribed values. Furthermore, the liquid-liquid equilibrium(LLE) phase diagrams of dex-MA/poly (ethylene glycol) (PEG)/water systems at 25℃ were experimentally determined for several dex-MAs of different DS. Finally, the swelling behavior of the hydrogels prepared with dex-MA of different DS was characterized by means of the blue-dex solution method as well as the gravimetric method.

Poly ( dimethylsiloxane ) - Solvent 계의 역 기체 크로마토그래피 연구

조정모,강춘형 한국공업화학회 1999 한국공업화학회 연구논문 초록집 Vol.1999 No.0

In this work, Inverse Gas Chromatography(IGC) at finite concentration is employed for the study of the interaction characteristics of poly (dimethylsiloxane) (PDMS) with various solvents such as water, ethanol, and iso-propanol. By measuring the specific retention volumes of the probes, the interaction parameters are calculated using the Flory-Huggins equation. From the results, the interaction parameters of the probes are, as expected due to the hydrophobicity of the polymer, found to be of large positive values(2$lt;x$lt;5). With the increase of alkyl chain length of the solvents, the interaction parameter decreases implying the relative favorite interaction with the PDMS. The IGC study is repeated for the cross-linked PDMS, which is prepared in our lab. By measuring the specific retention volumes of the probes, the cross-linking density is found to be about 2.0×10^(-3) mol/g according to the Flory-Rehner equation.

도로포장용 친환경 아스팔트 제조 기술

조정모,최선희,( Le Thi Hong Ngan ) 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

정유공정의 최하류로부터 얻어지는 아스팔트는 도로포장용 소재인 아스콘의 바인더로 사용된다. 아스콘의 제조공정 및 포설 시 다량의 휘발성 유증기를 발생하며, 이는 인체에 유해한 다환 방향족 화합물을 다수 포함하고 있어서 대기 환경오염의 주범이 되고 있으며, 이종원소(S, N 등)가 포함된 성분은 확산이 빠르고 저농도(ppb이하)에서도 심한 악취를 유발한다. 이를 해결하기 위한 다양한 물리적 화학적 방법들이 제안되어 왔으나, 대기오염 물질의 확산 자체를 근본적으로 차단할 수 있는 기술은 보고된 바 없다. 본 발표에서는 아스팔트 원료 내 악취 및 유해성분이 포함된 저비점 성분을 첨가제 또는 개질반응을 통해 미리 효과적으로 제거하여, 원료의 특성 변화를 최소화 하면서 악취나 유해성분이 발생하지 않는 친환경 원료의 제조 기술을 소개하고자 한다.