• Journal of The Korean Association For Science Education
• /
• v.40 no.3
• /
• pp.307-320
• /
• 2020

This study explores how the positioning of two pre-service science teachers (PSTs) is reflected in their different epistemic understandings of inquiry-based lessons. We collected the PSTs' products during their design and enactment of an inquiry-based lesson and recorded their practices in the enacted lesson. Interviews were recorded and transcribed for analysis. The results indicate that one PST, Dohyung was positioned as a subject of evaluation throughout the course and the other, Jinwoo, was positioned as a preservice teacher and a subject of evaluation. Their positions were reflected in their epistemic understandings of inquiry-based lessons, which were developed when designing these lessons. During lesson design, both PSTs showed a shared understanding; they explained inquiry-based lessons as students setting and evaluating hypotheses under teachers' guidance. However, as they faced unexpected situations during lesson enactment, they developed different epistemic understandings. To receive a good grade, Dohyung showed a strong preference for anticipating situations that could occur in class and planning responses to them. He understood inquiry-based lessons as ones in which students conduct experiments to produce results expected by the teacher. On the other hand, Jinwoo emphasized the reasoning process based on students' prior knowledge and explained inquiry-based lessons as ones in which students construct new knowledge through a scientific reasoning process based on their knowledge. The findings of this study will contribute to developing strategies to support PSTs' development of their epistemic understandings of knowledge construction in inquiry-based lessons.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.6
• /
• pp.443-453
• /
• 2020

This study using the active vibration control technique attempts to alleviate numerically the airframe vibration of a UH-60A helicopter. The AVCS(Active Vibration Control System) is applied to reduce the 4/rev vibration responses at the specified locations of the UH-60A airframe. The 4/rev hub vibratory loads of the UH-60A rotor is predicted using the nonlinear flexible dynamics analysis code, DYMORE II. Various tools such as NDARC, MSC.NASTRAN, and MATLAB Simulink are used for the AVCS simulation with five CRFGs and seven accelerometers. At a flight speed of 158knots, the predicted 4/rev hub vibratory loads of UH-60A rotor excite the airframe, and then the 4/rev vibration responses at the specified airframe positions such as the pilot seat, rotor-fuselage joint, mid-cabin, and aft-cabin are calculated without and with AVCS. The 4/rev vibration responses at all the locations and directions are reduced by from 25.14 to 96.05% when AVCS is used, as compared to the baseline results without AVCS.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.3
• /
• pp.143-152
• /
• 2020

Birnessite is a layered manganese oxide mineral with ~7 Å of d-spacing. Because of its high cation exchange capacity, birnessite greatly impacts the chemical compositions of ground water and fluids in sediment pores. Understanding the cation exchange mechanisms requires atomistic investigations of the crystal structures and coordination environments of hydrated cations in the interlayer. In this study, we conducted classical molecular dynamics (MD) simulations, an atomistic simulation method of computational mineralogy, for triclinic Na-birnessite and K-birnessite whose chemical formula are from previous experiments. We report our MD simulation results of the crystal structures, coordination environments of Na⁺ and K⁺, and the polytypes of birnessite and compare them with available experimental results. The simulation results well reproduced experimental lattice parameters and provided atomic level information for the interlayer cation and water molecule sites that are difficult to distinguish in X-ray experiments. We also report that the polytype of the Mn octahedral sheets is identical between Na- and K-birnessite, but the cation positions differ from each other, demonstrating a correlation between the coordination environment of the interlayer cations and the crystal lattice parameters. This study shows that MD simulations are very promising in elucidating ion exchange reactions of birnessite.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.13 no.4
• /
• pp.91-100
• /
• 2010

Existing traffic safety studies have focused on identifying the relationship among roadway crashes, highway design and incremental weather condition such as rainy/ice weather. However, it is hard to find researches that studied the effect of sun glare on traffic safety although there are abundant evidences demonstrating that fatal traffic crashes are attributed to the sun glare. Affecting drivers'vision particularly during the morning or the evening time when the sun positions close to the horizon, sun glare directly deteriorate drivers'judgmental capability. In this paper, we numerically analyze the effect of sun glare on the drivers'vision in time and space domains. Applied to the roadways around St Louis area in the United States, the GIS based simulation analysis identifies the time of day in a year and the segments of highways that are potentially influenced by the sun glare. This study evidentially confirms the fact that roadway bounded for West and East directions have longer time influenced by sun glare particularly during Spring and Fall season than other roadways. The computational result provides risky time periods of day at intersections or pedestrian crossings where the sun glare potentially endangers traffic safety, which be utilized to reduce the crashes due to the sun glare.

• Journal of Korean Academy of Nursing Administration
• /
• v.5 no.2
• /
• pp.389-400
• /
• 1999

The purpose of this study is to examine a possibility of applying the ABC system to analyze the cost of nursing service on one obstetrics and gynecology (OB/GYN) unit in a major medical center. The activities of nurses on an OB/GYN unit were analyzed for 4 days for 96 hours. 2 week days and 2 days on weekend. Total cases included in the study were activities of 12 charge nurses and 12 staff nurses. Activities were categorized into direct and indirect activities in order to calculate the cost of activities. Nursing activities were defined multidimesionally in order to utilize the ABC system. The 60 nursing activities were classified into the direct nursing activities and the indirect nursing activities based on a literature review, interview, and survey results. The direct activities were further categorized into the single nursing activities and the multiple nursing activities. The indirect activities were classified into the indirect nursing service activities and the general management activities. The major findings of this study were as follows : 1. There were differences in activities according to the positions and duties of the nurses. The charge nurses mostly performed the indirect nursing service activities and the general management activities. Almost all of their indirect nursing activities spent on each patient were similar. The staff nurses performed the single nursing activities and the multiple nursing activities. 2. The activities of staff nurses included medication, patient assessment, rounding and organizing the unit. patient education, nursing treatment, admission and discharging of patients. There was no differences in types and amount of time spent between the nurses on day-time duty and evening-time duty, but the patient assessment activity increased during the night-time. 3. The cost of post partum nursing services for women who had a normal vaginal delivery using the ABC system included the cost incurred by direct nursing activities provided by the staff nurses (85.9%), indirect nursing activities incurred by the staff nurses(19.0%) and the nursing activities by the charge nurses and the head nurse(14.1%). The ABC system is a relatively new method of cost analysis. The results of this study can provide the nursing and hospital managers with useful information on cost control. It is suggested that more studies should be done using the ABC system and extend the scope of studies to include value analysis to aid the Activity-Based Management(ABM) and/or the reengineering of hospital process.

• Journal of Korean Academy of Nursing
• /
• v.28 no.2
• /
• pp.498-509
• /
• 1998

The phrases such as elders' powerless soliloquy or stammering and their positions unadjusted to the real world are, so far, one of negative views on elder's reminiscences. In other words, it means that elders can get psychological consolation from the getting themselves absorbed in their past. The starting point of this study is, however, that elders' reminiscence are their own mode of the existence. This dissertation is studied through Van Manen's phenomenological research method. The aim of this study is to examine the nature of Korean elders' reminiscences by both observing and describing the reminiscing content in everyday life of elders. The research participants consist of the ten elders who are community elders, hospitalized elders and nursing home residents. The period of the research is about a year from Jan., 1996 to Feb., 1997. The results of this study are as follows : The natures of elders' reminiscences are the regrecting on their life, mitigating the regrects, the confirmation of the powers and the confirmation of their life's mark. The regrecting on their life is the starting point of elders's reminiscences. Elders have tried to examine their life through reflection on their life that they did not live good life as son and daughter for parents and as parents for children and that they have foolishly lived, on dream that they did not come true, on their learning that they did not unsatisfied. But elders mitigate the regrects. They have felt their limitations of power in the conflict of human relation, the economic matter and the difficult predicament, and have finally accepted their life as it is by conquesting from their tenacity. It is dynamically found that both the regrecting on their life and mitigating of the regrection. And they pursuit the powers. It means the pursuit of the vital powers, the vigorous powers and the competency. Elders have pursued their vitality, vigor and competency through their reminiscences and have wanted to be recognised by others as a powerful being. These have dynamic and compounded aspects. The confirmation of their life's mark refer to through their own situation of health, condition, children, neighbourhood and doing their duty as a human. Elders have confirmed the present value of their being through the reflecting the present, past self, other men around themselves, children, neighborhood and the doing their human duty as a good men. Therefore the results of this study can offer new view on the elders' reminiscences that we have to understand them as a process as what they are, escaping from the simple logic that elders' reminiscence have a positive or a negative effects. Also, this study which have examined the natures of Korean elders' reminiscences can cast a new light on elders' nursing proper for Korean culture.

• The korean journal of orthodontics
• /
• v.26 no.4
• /
• pp.423-439
• /
• 1996

The purpose of this study was to evaluate the diagnostic value of $SONOPAK^*$ in internal derangement of TMJ by comparing the spectral analysis data of TMJ sounds recorded by SONOPAK with the results of MRI. From the patients who came to Department of Orthodontics, Seoul National University Dental Hospital for treatment of malocclusion, eighteen adult patients (five males and thirteen females) with TMD symptoms were selected. After joint sounds were checked by a pediatric stethoscope, they were recorded and analyzed by the SONOPAK. The spectral analysis of the SONOPAK provided SONOPAK INTERPRETATION data about the stage of internal derangement, which were compared with the results of MRI. Among the patients whose disc positions were diagnosed as 'normar by MRI, there were no false positive diagnosis by the SONOPAK INTERPRETATION, But in the cases of anterior disc displacements (reducible and/or nonreducible), most of SONOPAK INTERPRETATION data did not coincide with MRI results. In conclusion, it is not adequate to try to differentiate reducible and non-reducible anterior disc displacements on the basis of joint sounds. And it is recommended not to determine the stage of internal derangement according to the nature of sounds. We suggest that the diagnostic value of the SONOPAK will be enhanced when clinicians combine some other informations such as clinical signs/symptoms and other supplementary diagnostic tools), and that more data be incoporated into the SONOPAK INTERPRETATION software.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.9
• /
• pp.1405-1417
• /
• 2006

The geometrical structures, potential energy surfaces, and energetics for the ligand exchange reactions of tetracoordinated platinum $(PtY_2L_2\;:\;Y,\;L=Cl^-,\;OH^-,\;OH_2,\;NH_3)$ complexes in the ligand-solvent interaction systems were investigated using the ab initio Hartree-Fock (HF) and Density Functional Theory (DFT) methods. The potential energy surfaces for the ligand exchange reactions used for the conversions of $(PtCl_4\;+\;H_2O)^{^\ast_\ast}\;to\;[PtCl_3(H_2O)\;+\;Cl^-]$ and $[Pt(NH_3)_2Cl_2\;+\;H_2O]$$[Pt(NH_3)_2Cl_2\;+\;H_2O]$ to $[Pt(NH_3)_2Cl(H_2O)\;+\;Cl^-] $ were investigated in detail. For these two exchange reactions, the transition states $([PtY_2L_2{\cdot}{\cdot}{\cdot}L^\prime])^{^\ast_\ast} $ correspond to complexes such as $(PtCl_4{\cdot}{\cdot}{\cdot}H_2O)^{^\ast_\ast}$ and $[Pt(NH_3)_2Cl_2{\cdot}{\cdot}{\cdot}H_2O]^{^\ast_\ast}$, respectively. In the transition state, $([PtCl_4{\cdot}{\cdot}{\cdot}H_2O]^{^\ast_\ast}$ and $[Pt(NH_3)_2Cl_2{\cdot}{\cdot}{\cdot}H_2O]]^{^\ast_\ast})$ have a kind of 6-membered $(Pt-Cl{\cdot}{\cdot}{\cdot}HOH{\cdot}{\cdot}{\cdot}Cl)$ and $(Pt-OH{\cdot}{\cdot}{\cdot}Cl{\cdot}{\cdot}{\cdot}HN)$ interactions, respectively, wherein a central Pt(II) metal directly combines with a leaving $Cl^-$ and an entering $H_2O$. Simultaneously, the entering $H_2O$ interacts with a leaving $Cl^-$. No vertical one metal-ligand interactions $([PtY_2L_2{\cdot}{\cdot}{\cdot}L^\prime]) $ are found at the axial positions of the square planar $(PtY_2L_2)$ complexes, which were formed via a vertically associative mechanism leading to $D_{3h}$ or $C_{2v}$-transition state symmetry. The geometrical structure variations, molecular orbital variations (HOMO and LUMO), and relative stabilities for the ligand exchange processes are also examined quantitatively. Schematic diagrams for the dissociation reactions of {PtCl4(H2O)n(n=2,4)} into {$PtCl_3(H_2O)_{(n-2)}\;+\;Cl^-(H_2O)_2$} and the binding energies {$PtCl_4(H_2O)_n$(n = 1-5)} of $PtCl_4$ with water molecules are drawn.

• Management & Information Systems Review
• /
• v.17
• /
• pp.191-214
• /
• 2005

Recently, most enterprises are having a knowlege management boom. A number of books associated with the knowlege management are being published, countless public seminars are held, and many research councils have been organized studying it formally or informally as if not importing the system is like falling behind a fashion. However, there are not many cases that achieved success by constructing the system of knowledge management. Then, why the knowledge management is not so much effective despite so many voices wanting the change of management system and a lot of public lectures about it? I guess the reason is that most companies do not have concrete methodology. Seeing a result of a survey which reported that with spread of venture boom and successful examples being known widely, the outflow of precious human resources is accelerated and a large number of employees of conglomerates have already resigned or are considering separation from their positions, we can realize that are occurring a change which can be nearly called severance in an occupational view and an organization culture. The preference to a large enterprise or a public institution of labor is low today and the notion about a lifelong job is regarded as past remains. As for this, it could be said that the social atmosphere that pursued the stability of a job has been changed to the practical one that attaches importance to ability and pay. The way of thinking of employees has been changed while established organizations cannot satisfy their desire and this explains why important members of a company are flown out. The reason why superior human resources move to venture businesses is that they can do their likable work and also prove their ability as well as unconventional rewards. Although existing companies are trying to preserve important human resources through performance compensating stock option, temporary patching up of personnel management cannot retard the rushing wind of foundation and the outflow of labor. On the contrary, clumsy import of performance-based reward system not only fails to hire superior labor power but also can bring about a sense of incompatibility and conflicts among the remaining employees. Therefore, this thesis, focusing on how to choose, develop, and maintain the human resources, will suggest a future-aiming human resources management model of Korean enterprises after comparing and analyzing the actual condition of domestic companies and the trends of advanced corportaions.

• The Journal of Dong Guk Oriental Medicine
• /
• v.7 no.2
• /
• pp.141-148
• /
• 1999

A simple and rapid FoLT(formamide low temperature)-PCR, whereby human genomic DNA from blood can be amplified without DNA preparative stps, is described using human insulin genes. By applicatin of FoLT-PCR in human insulin genes, intragenic polymorphism in non-coding regions of the human insulin gene was shown after amplification and analysis by restriction enzyme digestion. All nucleotide sequences were the same as the reported, and four necleotides, at 4 different positions were polymorphic, and polymorphic alleles ${\alpha}4$, ${\alpha}5$, ${\alpha}6$, and ${\beta}2$ were identified. The new alleles were originated from homologous recombination between the ${\alpha}1$ and ${\beta}1$ alleles, and the alleles were founded in heterozygotes only. Although allele ${\alpha}1$ was dominant, the new alleles and ${\beta}1$ were recessive. From the results, it was suggested that the new method of FoLT-PCR was highly applicable in genetic variation analysis.