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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Chemical Society
Journal Basic Information
Journal DOI :
Korean Chemical Society
Editor in Chief :
Byeong Moon Kim
Volume & Issues
Volume 50, Issue 6 - Dec 2006
Volume 50, Issue 5 - Oct 2006
Volume 50, Issue 4 - Aug 2006
Volume 50, Issue 3 - Jun 2006
Volume 50, Issue 2 - Apr 2006
Volume 50, Issue 1 - Feb 2006
Selecting the target year
New Research Tool for Understanding of Surfaces - Sum Frequency Generation Vibrational Spectroscopy
Kim, Hak-Jin ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 429~439
DOI : 10.5012/jkcs.2006.50.6.429
vibrational spectrum of molecules on surfaces can be measured with high selectivity and sensitivity using sum frequency generation vibrational spectroscopy (SFG-VS). Selectivity and sensitivity of this non-linear spectroscopy have made it an effective experimental tool in surface research. Surface systems studied with SFG_VS are surveyed, and experimental and theoretical background of SFG-VS is briefly reviewed.
Preparation of ZnO Nanoparticles by Laser Ablation of Dispersed ZnO Powder in Solution
Gang, Wi-Gyeong ; Jeong, Yeong-Geun ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 440~446
DOI : 10.5012/jkcs.2006.50.6.440
ZnO nanoparticles were prepared by laser ablation of the ZnO powder dispersed in deionized water and surfactant solutions, and characterized using UV-VIS absorption spectroscopy, X-ray diffractometer and Transmission electron microscopy(TEM). ZnO nanoparticles produced show the pure ZnO crystal state without mixed state with Zn(OH)2 or Zn, and have the band gap energy of 3.35 eV, which is comparable to that of bulk ZnO. While ZnO nanoparticles prepared in SDS solution have the average diameter of 28nm with near spherical shape, those prepared in CTAB solution have the average size of 40 nm with mainly rod-like shape. ZnO colloidal solution of CTAB is more stable than that of SDS. These difference according to surfactants can be explained by difference of electrostatic interaction between surface charge of ZnO and surfactant molecules and by solvation effect in solution.
Thixotropic Properties of Polyacrylamide Hydrogels with Various Synthetic Conditions
Kim, Nam-Jeong ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 447~453
DOI : 10.5012/jkcs.2006.50.6.447
of synthetic conditions and water content on rheological properties of polyacrylamide hydrogels were studied. The non-Newtonian flow curves of polyacrylamide hydrogels were obtained by using a cone-plate rheometer. The rheological parameters were obtained by applying non-Newtonian equation to the flow curves for polyacrylamide hydrogels. The polyacrylamide hydrogels are shear thinning under increasing shear rate modes which result in thixotropic behavior. These flow properties are controlled by the characteristics of flow units and the interaction among the flow segments.
Characteristics of Decomposition for Refractory Organic Compounds in Aqueous Solution by Sonolysis and Electrolysis
Jeong, Jae-Baek ; Lee, Seong-Ho ; Bae, Jun-Ung ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 454~463
DOI : 10.5012/jkcs.2006.50.6.454
refractory organic compounds in aqueous solution are not readily removed by the existing conventional wastewater treatment process. In recent years, the sonolysis and electrochemical oxidation process had been shown to be promising for wastewater treatment due to the effectiveness and easiness in operation. This study was performed to investigate the characteristics of sonolytic and electrolytic decomposition as the basic data for development of the wastewater treatment process. Trichloroethylene(TCE) and 2,4- dichlorophenol(2,4-DCP) were used as the samples, and their destruction efficiency were measured with various operating parameters, such as initial solution concentration, initial solution pH, reaction temperature, sonic power and current density. Also, the decomposition mechanism conformed indirectly with the effect of NaHCO3 as a radical scavenger on the decomposition reaction. Thermal decompositon reaction is predominant for TCE but thermal and radical decompositon reactions were dominant for 2,4-DCP. Results showed that the destruction efficiencies of all samples were above 65% within 120 minutes by sonolysis and electrolysis at the same time, and were increased with increasing initial concentration, sonic power and current density. Destruction efficiency of TCE was high in the acidic solution, but 2,4-DCP showed high destruction efficiency in basic solution.
Preparation of the Dexamethasone-incorporated Lipid Nanosphere: Characteristics of Lipid Nanosphere by Varying Species and Ratio of Lipid
Jeong, Seok-Hyeon ; Lee, Jeong-Eun ; Seong, Ha-Su ; Sin, Byeong-Cheol ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 464~470
DOI : 10.5012/jkcs.2006.50.6.464
the coricosteroid drug dexamethasone is an efficacious antiinflammatory drug, it is difficult to formulate in an injectable formulation due to its poor aqueous solubility. A lipid-based nanosphere formulation containing dexamethasone was designed for solubilization of the drug in aqueous solution and sustained release of the drug from the nanosphere. The lipid nanospheres, composed of phospholipid, cholesterol and cationic lipid, were prepared by self emulsification-solvent diffusion method followed by diafiltration. Physicochemical characteristics such as mean particle diameter, zeta potential and drug loading efficiency of the lipid nanospheres were investigated according to the variation of either the kind of lipid or the lipid composition. The lipid nanospheres had a mean diameter 80-120 nm and dexamethasone loading efficiency of greater than 80%. The drug loading efficiency increased with the increase of the length of aliphatic chain attached to the phospholipid. However, the drug loading efficiency was inversely proportional to the increase of cholesterol content in the lipid composition. The lipid nanosphere could not be prepared without the use of cationic lipid and the drug loading efficiency was proportional to the increase of cationic lipid content. The lipid nanospheres containing dexamethasone are a promising novel drug carrier for an injectable formulation of the poorly water-soluble drugs.
Synthesis and Optical Properties of Ca1-xSrxS:Ce Phosphors
Heo, Yeong-Deok ; Seong, Hye-Jin ; Do, Yeong-Rak ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 471~476
DOI : 10.5012/jkcs.2006.50.6.471
series of Ca1-xSrxS:Ce phosphors were synthesized by solid-state reactions. The Ca1-xSrxS:Ce phosphors have a strong absorption in region from 430 nm to 470 nm. The emission peaks of CaS:Ce are located at 510 nm and 570 nm. The partial replacement of Ca by Sr in Ca1-xSrxS:Ce causes a blue shift of emission wavelengths. The Ca1-xSrxS:Ce can be used as bluish green and yellow emitting phosphors for white light emitting diodes (LEDs) pumped by the blue LED. We reported the optical properties of Ca1-xSrxS:Ce phosphors for application in phosphor converted white LEDs.
The Influences of the Forms of Verbal External Representations and Students’ Verbal Learning Style in Learning with Multiple Representations Using Drawing
No, Tae-Hui ; Gang, Hun-Sik ; Lee, Byeong-Jin ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 477~485
DOI : 10.5012/jkcs.2006.50.6.477
study investigated the influences of the forms of verbal external representations and students' verbal learning style in learning chemical concepts with drawing as a method to assist students in connecting and integrating multiple external representations. Seventh graders (N=133) at a coed middle school were assigned to formal drawing (FD) and personalized drawing (PD) groups. Students in the PD group were provided words at personalized style as verbal external representations for drawing, while those in the FD group were provided words at formal style. All students were taught about Boyles Law and Charless Law for two class hours. Results revealed that the scores of a conception test for the PD group were significantly higher than those for the FD group. In a situational interest test, students with strong verbal learning style preference scored significantly higher than students with weak verbal learning style preference in the two groups. Most PD group students were found to prefer to read verbal external representations at personalized style for drawing rather than at formal style, and perceived their activities positively upon cognitive, affective and motivational aspects. Students with strong verbal learning style preference had more positive perceptions about their activities than students with weak verbal learning style preference especially upon affective and motivational aspects.
Relationship between Conceptual Understanding and Mapping Errors Induced in Learning Chemistry Concept with Analogy
No, Tae-Hui ; Kim, Gyeong-Sun ; Sin, Eun-Ju ; Han, Jae-Yeong ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 486~493
DOI : 10.5012/jkcs.2006.50.6.486
study investigated the relationship between conceptual understanding and mapping errors induced in learning chemistry concept with two analogies presented in current science textbooks. Each of the two groups from 7th graders (N=260) in three middle schools studied with one of the analogies, and then a conception test and a mapping test were administered. Analyses of the results indicated that students conceptual understanding has a significant relationship with their understanding about the mapping. The scores of the conception test and the mapping test for the unshared attributes were lower than those for the shared attributes. Five types of mapping errors were also identified: overmapping, mismapping, failure to map, rash mapping, and artificial mapping. Many representative misconceptions were found to be associated with their mapping errors. Educational implications are discussed.
Characteristics of Verbal Interactions According to the Leader Style in MBL Experiment Class in Which Discussion was Emphasized
Gu, Yang-Sam ; Park, Geum-Hong ; Sin, Ae-Gyeong ; Choe, Byeong-Sun ; Lee, Guk-Haeng ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 494~505
DOI : 10.5012/jkcs.2006.50.6.494
This study was performed for 7th grade students to analyze by leader style, the verbal interactions between students in a small group in an MBL(Microcomputer-Based Laboratory) experiment class. The study was performed after arranging the students into four kinds of groups, including groups with leaders of inclusive, persuasive, and alienating styles and a group with no clear leader. The analysis of total frequencies of verbal interaction revealed that the group with an inclusive leader showed the highest frequency of verbal interaction, followed by the group with a persuasive leader, an alienating leader and lastly, the group with no clear leader. The group with an inclusive leader showed the highest frequency of interaction from a cognitive aspect related to question(Q), response(R), making suggestion(MS), and receiving opinions(RO), while interactions from an affective aspect related to behavioral participation(BP) and students' attitudes(SA) were observed more often in a group including an alienating leader than in any other group. An analysis of characteristics of verbal interaction according to leader style showed that a group with an inclusive leader had a permissive atmosphere. It also showed that all members of the group actively participated in discussion and they had a sense of belonging and self-pride with their group. In a group with a persuasive leader, the leader took the lead of most experimental and discussion activities and he was rarely challenged by other students in the group. Rather, other group members showed a tendency to depend on their leader. In a group with an alienating leader, the relationship between leader and members of the group was not harmonious and unfiltered expressions of dissatisfaction and ignorance often took place. The leader's lack of concern about members' low achievement became an obstacle in active discussion. In a group with no clear leader, most interactions during discussion were short and simple. Many answers to the question given by their members were not clear and the interactions were sometimes interrupted for a short while.
Application Effects of Out-of-class Chemical Experience Learning Programs on Scientific Process Skills and Science-Related Attitude for Middle School Students
Mun, Seong-Bae ; Jo, Mi-Ae ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 506~514
DOI : 10.5012/jkcs.2006.50.6.506
purpose of this work was to study the applied effects of out-of-class Chemical Experience Learning (CEL) Programs on scientific process skills and science-related attitude for middle school students. The out-of-class CEL Programs which were developed to make the funny out-of-class chemistry and the exciting science class', included the nature-friendly chemical experiments suitable for natural environment and composed of real life-centered experiences. The out-of-class CEL programs were applied to natural environment through all-day improvement activity. The science club students in D middle school in Busan were selected as the objects of the study consisting of one experiment group and one control group. The out-of-class CEL programs were applied to the experiment group and traditional class method was applied to the control group. The change of scientific process skills and science-related attitudes between two groups were compared and analyzed. And students reaction on the out-of-class CEL programs was investigated. As a result, out-of-class nature-friendly chemical experiments were improved scientific process skills and science-related attitudes of middle school students. Also, more than 70% of students in the experimental group gave positive feedbacks to the out-of-class CEL programs and increased attention, interest, and degree of self-participation in science.
Cholic acid에 의한 라세믹-글리시돌의 분할
Lee, So-Ha ; Raja, Inam ul Haq ; Jeon, Je-Ho ; Jeong, Chan-Seong ;
Journal of the Korean Chemical Society, volume 50, issue 6, 2006, Pages 515~517
DOI : 10.5012/jkcs.2006.50.6.515