수용액 중에서 고분자 전자주게와 전자받게의 착체형성에 대한 연구

장춘학,류필조 世明大學校 1998 世明論叢 Vol.7 No.-

Under various surrounding conditions, the complexation between polymeric electron-donnor(poly acrylic acid) and elecron-acceptor (poly ethylene oxide and poly vinyl alcohol) througy secondary force in aqueous media hs been studied by using GPC, UV, PH meter and Ubbelohde type viscometer. It is found that the type and active site for complexation are influenced by the bothe of functional group of electron-donnor and elecron-acceptor. The addition of inorganic salts in water seemed to impede the secondary force bonded complexation. The results could be explained in terms of hydrodynamic dimension and elecrostatic interation included.

Non-Newtonian Intrinsic Viscosities of Biopolymeric and Non-biopolymeric Solutions (II)

Jang, Chun-Hag,Kim, Chang-Hong,Ree, Taik-Yue Korean Chemical Society 1987 Bulletin of the Korean Chemical Society Vol.8 No.4

This paper is a continuation of our previous $paper,^1$ and deals with Eq.(1) (see the text), which was theoretically derived in the $paper,^1$$ [{\eta}]^f\; and\; [{\eta}]^0$ is the intrinsic viscosity at stress f and f = O, respectively. Equation (1) predicts how $[{{\eta}}]^f / [{\eta}]^0$ changes with stress f, relaxation time ${\beta}_2$ of flow unit 2 and a constant $c_2$ related with the elasticity of molecular spring of flow unit 2. In this paper, Eq.(1) is applied to a biopolymer, e.g., poly (${\gamma}$-benzyl L-glutamate), and nonbiopolymers, e.g., polyisobutylene, polystyrene, polydimethylsiloxane and cellulose triacetate. It was found that the $c_2$ factor is zero for non-biopolymers while $c_2{\neq}0$ for biopolymers as found $previously.^1$ Because of the non-Newtonian nature of the solutions, the ratio $[{{\eta}}]^f / [{\eta}]^0$ drops from its unity with increasing f. We found that the smaller the ${\beta}_2,$ the larger the $f_c$ at which the viscosity ratio drops from the unity, vice versa.

Molecular Conformation and Non-Newtonian Viscosity Behavior of Poly(L-proline) in Various Solvent Systems

Jang, Chun-Hag,Kim, Hyun-Don,Lee, Jang-Oo Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.5

The non-Newtonian viscosities (the specific or intrinsic viscosities) of poly(L-proline) (PLP, $M_v$=19,000 and 32,000) in various mixed-solvent systems like water-propanol and acetic acid-propanol of varying compositions were measured during the reverse mutarotation (Form II ${\rightarrow}$Form I) by the application of external pressure (up to 4.5 psi). The non-Newtonian viscosity effect was found to be larger in acetic acid-propanol system than in water-propanol system and to somewhat decrease during the reverse mutarotation at a given solvent system. The non-Newtonian viscosity behavior of PLP in aqueous salt ($CaCl_2$) solution was also studied, from which it was found that the degree of the non-Newtonian effect decreased with increasing salt concentration, and increased with increasing PLP molecular weight. These findings could be explained in terms of conformational changes of PLP in solution (like the helix-helix or helix-coil transition) involved.

Superplastic Deformation in the Low Stress Region

Jang, Chun-Hag,Kim, Chang-Hong,Ree, Tai-Kyue Korean Chemical Society 1984 Bulletin of the Korean Chemical Society Vol.5 No.2

Superplastic alloys generally exhibit a three-stage sigmoidal variation of stress (f) with strain rate (s), the stages being named region 1, 2 and 3 according to the increasing order of stress or strain rate. In the recent years, two different types of papers have been published on the plastic deformation of Zn-22% Al eutectoid in region Ⅰ differing in strain-rate sensitivity m (= dln f/dln s). In this paper, the data of the two groups have been analysed by applying Kim and Ree's theory of superplastic deformation. (1) We obtained the parametric values of $X_{gj}/{\alpha}_{gj}\;and\;{\beta)_{gj}$ (g: grain boundary, j = 1,2 indicating flow units) appearing in Kim and Ree's theory [Eq. (2a)]. (2) It was found that the value of $X_{g^2}/{\alpha}_{g^2}$ is small for the group data with small m, i.e., ${\alpha}_{g^2}$, which is proportional to the size of flow unit g2, is large whereas ${\alpha}_{g^2}$ is small for the groups data with large m, i.e., the size of the flow unit g2 is small. In other words, the two types of behavior occur by the size difference in the flow units. (3) From the ${\beta}_{gj}$ value, which is proportional to the relaxation time of flow unit gj, the ${\Delta}H_{gj}^{\neq}$ for the flow process was calculated, and found that ${\Delta}H_{g^2}^{\neq}$ is large for the group data with small m whereas it is small for the group data with large m. (4) The flow-unit growth was studied, but it was concluded that this effect is not so important for differentiating the two groups. (5) The difference in ${\alpha}_{g^2}$ and in the growth rate of flow units is caused by minute impurities, crystal faults, etc., introduced in the sample preparation.

Development of a Ro- Ro Passenger Ferry with a Large High-Speed Monohull

Jang, Hag-Soo,Joo, Young-Ryeol,Chun, Ho-Hwan The Korean Association of Ocean Science and Techno 2004 Journal of Ocean Science and Technology Vol.1 No.1

Samsung Heavy Industries built and delivered three large high-speed Ro-Ro passenger ferries for Minoan Lines from 2001 to 2002. This paper presents the application method of computational fluid dynamics for hull form optimization and the results of model test and sea trial. In addition to this, the core technology for passenger vessel, i.e., the design concept of general arrangement, interior design, equipment and system design will be described.

수용액에서 산성고분자와 염기성고분자의 착체형성

장춘학 청주대학교 2007 産業科學硏究 Vol.25 No.1

Under various surroundings, the complexation between acidic polymer(poly acrylic acid) and basic polymer(poly ethylene oxide) through secondary force in aqueous media has been studied by using GPC, UV, pH meter and Ubblelohde type viscometer. It is found that the type and active site for complexation are influenced by the both of functional group of proton-donor and proton-acceptor. From the UV measurement of this complex system, the UV absorbance of the band of n-π* decreases while that of π-π* increases with pH has presented evidence for the site of complexation. The addition of inorganic salts in this aqueous system seemed to impede the secondary force bonded complexation. The results could be explained in terms of hydrodynamic dimension and electrostatic included.

Some practical design aspects of appendages for passenger vessels

Jang, Hag-Soo,Lee, Hwa-Joon,Joo, Young-Ryeol,Kim, Jung-Joong,Chun, Ho-Hwan The Society of Naval Architects of Korea 2009 International Journal of Naval Architecture and Oc Vol.1 No.1

The hydrodynamic effect of appendages for high-speed passenger vessels, such as Ro-Pax, Ro-Ro and cruiser vessels, is very severe and, therefore, it is essential to carry out the design of appendages for high-speed passenger vessels from the preliminary design stage to the final detail design stage through a full survey of the reference vessels together with sufficient technical investigation. Otherwise, many problems would be caused by mismatches between the appendages and the hull form. This paper investigates the design characteristics of some appendages, such as the side thruster, the shaft-strut, and the stern wedge, based on the design experience accumulated at Samsung, on CFD, and on model test results for high-speed passenger vessels. Further to this investigation, some practical and valuable design guidelines for such appendages are suggested.

고속 대형여객선의 선형특성에 대한 연구

장학수(Hag-Soo Jang),이화준(Hwa-Joon Lee),주영렬(Young-Ryeol Joo),전호환(Ho-Hwan Chun) 대한조선학회 2003 大韓造船學會 論文集 Vol.40 No.4

직접에탄올 연료전지의 운전조건에 관한 연구

김영춘(Young-Chun Kim),구본국(Bon-Kook Koo),장문국(Mun-Gug Jang),지학배(Hag-Bae Ji),한상보(Sang-Bo Han),박재윤(Jae-Youn Park) 대한전기학회 2011 전기학회논문지 Vol.60 No.11

The goal of this paper is to find an operating conditions of the single direct ethanol fuel cell such as the cell temperature, and flow rates of ethanol and oxygen. To investigate the output characteristics, the electrical current increased from 0[A] with interval of 0.001[A] every 2[s], and the cell voltage was increased until the voltage became 0.05[V]. Related to the effect of the cell temperature, the output characteristics both voltage and power were increased upto 80[℃] according to the increase of the current density, but those were decreased over that temperature. In addition, the optimal flow rate of ethanol in anode was identified as of 2[mL/min] due to the dependence of generation rate such as the hydrogen ion and electron. And the flow rate of oxygen in cathode was desirable to about 300[sccm/min], it might be affected by the chemical reaction rate of the water formation among hydrogen ion, electron, and oxygen. Consequently, the fundamental conditions were identified in this work, and it will be carried out to find the best conditions of membrane by the effect of the plasma surface treatment, and the effect of other catalysts except for a platinum.

Characteristics of (Sr_1-xBa_x)NdFe³⁺_1-_τFe⁴⁺_τO_4-y System Heat-treated in Air

Lee, Eun-Seok,Hag, Jang-Chun The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.1

To study the physical and chemical properties, solid solutions of $(Sr_{1-x}Ba_x)NdFe{^{3+}}_{1-\tau}Fe{^{4+}}_{\tau}O_{4-y}$ system with x=0.0(SBN-0), 0.1(SBN-1), 0.2(SBN-2) and 0.3(SBN-3) were synthesized in air at 1,473 K and annealed in air at 1,073 K for 24 h. X-ray powder diffraction assured that the four samples had tetragonal symmetries (I4/mmm). Their lattice volumes increased gradually with x values. Nonstoichiometric chemical formulas were formulated using the data such as $\tau$(amount of $Fe^{4+}$ ion) and y(oxygen deficiency) values using Mohr salt analysis. It was found out that all the four samples had excessive oxygen (4-y>4.0). All the samples started to lose some of their oxygen at around 613K(TG/DTA thermal analysis). They exhibited semiconductivities in the temperature range of around 283-1173K. All the four specimens had sufficient tensile strength to endure the force of 19.6 N (2 kg of weights) and the conductivity values of the ECIAs which were painted on pieces of glass with the area of $150mm^2$ ($10mm{\times}15mm$) and it was in the order of ECIA-0${\rightarrow}$ECIA-1${\rightarrow}$ECIA-2${\rightarrow}$ECIA-3 at a constant temperature.