초등학교 입학 이후 아동의 학교적응에 대한 교사 요인의 영향

곽나람 ( Naram¸ Gwak ),윤예린 ( Yerin¸ Yoon ),김성식 ( Sung Sik¸ Kim ) 한국초등교육학회 2021 초등교육연구 Vol.34 No.1

이 연구에서는 초등학교 입학 이후 아동의 학교적응에 대한 교사 요인의 영향을 종단적으로 분석하고자 하였다. 이를 위해서 한국아동패널 데이터를 활용하여 아동의 초등학교 입학 직후 학교적응 수준과 그 이후 4년 동안 변화 정도를 2수준 다층성장 모형을 통해 분석하였다. 분석 결과 초등학교 1학년 시점 학교적응에 대해서 교사-아동 관계와 아동의 교사 선호도가 아동의 성별, 부모학력, 가구소득, 학습준비도 등을 통제한 후에도 긍정적인 영향력을 가지고 있는 것으로 나타났다. 그 이후 학교적응의 변화에 대해서는 교사-아동 관계가 긍정적인 영향을 미치고 있었고, 다른 변인들을 통제했을 때에도 유지되는 것으로 나타났다. 가정 배경, 부모의 양육태도, 아동의 학습준비도 등이 초등학교 입학 직후 아동의 학교적응에 영향을 미치기는 하지만, 그 이후에는 주된 영향 요인이 교육활동 속에서 직접 경험하게 되는 교사와 아동의 관계로 전환된다는 것이다. 이러한 분석 결과를 토대로 유·초 전환기 아동들의 성공적인 학교적응을 위한 시사점을 논의하였다. The purpose of this study was to analyze longitudinally the effect of teacher factors on school adjustment of children after entering elementary school. To this end, using the data from PSKC(Panel Study on Korean Children), the level of school adjustment in grade 1 and the slope of grade 1 to grade 4 were analyzed through two-level growth model. Teacher-student relationship and students' preference for teachers in the first grade of elementary school have a positive effect on the initial school adjustment, even after controlling children's gender, parents’ education level, household income, and school readiness. Also, teacher-student relationship is positively related to the slope of school adjustment, while parent-child interactions, learning attitude and communication (school readiness) is functioned positively. The influence of teacher-student relationship was maintained when the other variables were controlled. Although family background, parenting attitudes, and children's school readiness affect children's school adjustment immediately after entering elementary school, the main factor becomes teacher-student relationship that children experience directly in educational activities. Based on the results of this analysis, the implications for successful school adjustment of children were discussed.

Radiological Characteristics of the Havar Foil in the Cyclotron Target

Dong gun Jang,Sang hwa Shin,Chang lak Kim,Gyeong hyeon Gwak2 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

The cyclotron is an apparatus used for the production of radioactive isotopes through nuclear reactions, resulting in the inevitable emission of neutrons. Consequently, surrounding components become activated. The purpose of this study was to investigate the radiological characteristics of Havar foil, a periodic replacement part of the Targetry system. In this study, radioactivity and radiation dose were calculated based on the time of Havar foil replacement and equipment dismantling. The time to dismantle the equipment was set at one year after the equipment was shut down, based on the recently used 1g of Havar foil. All simulations were performed using the FLUKA program. First, in the simulation results, 11 elements (Re, W, Tc, Nb, Cu, Ni, Co, Fe, Mn, Cr, V) were converted into 36 radioisotopes by activation based on the replacement period. Based on radioactivity levels, major isotopes included 52Mn (77.63%), 56Co (13.36%), 96Tc (2.4%), and 95Tc (1.80%). Based on radiation dose rates, 52Mn (82.66%) and 56Co (13.45%) exhibited the highest levels. Furthermore, the dose rates at distances of 10 cm, 50 cm, and 100 cm were found to be 1.36E+1 mSv/hr, 2.24E+00 mSv/hr, and 8.80E-01 mSv/hr, respectively. Second, as of the time the equipment was dismantled, 20 radioactive isotopes of 10 elements, excluding short-lived nuclides, were generated. In terms of radioactivity, 56Co (45.83%), 55Fe (19.73%), 57Co (14.48%), and 54Mn (13.50%) were prominent. Regarding radiation dose rates, 56Co (92%) and 54Mn (7.32%) exhibited higher levels. Dose rates at distances of 10 cm, 50 cm, and 100 cm were calculated at 5.31E-01 mSv/hr, 8.80E-02 mSv/hr, and 3.47 E-02 mSv/hr, respectively. Third, according to the radioactive waste classification standards in the replacement and decommissioning stages, Havar foil was predicted to be low-level radioactive waste in terms of radioactivity. In addition, it was derived that a cooling period of approximately 12 years is necessary to satisfy the allowable dose for clearance level waste. In conclusion, Havar foil, which is periodically generated as radioactive waste, can cause radiation exposure to replacement workers. Therefore, special and careful management is required for the Havar foil of the cyclotron.

Comparison of Shoulder Total Rotational Range of Motion and External to Internal Rotation Strength Ratio between Assembly Line Workers with and without Subacromial Pain Syndrome

Gyeong-tae Gwak(Gyeong-tae Gwak),Young-soo Weon(Young-soo Weon),Jun-hee Kim(Jun-hee Kim) KEMA학회 2022 근골격계과학기술학회 Vol.6 No.1

Background Subacromial pain syndrome (SAPS) is one of the causes of shoulder pain in workers performing repetitive upper extremity movements. However, there have been no studies on physical characteristics such as shoulder total rotational range of motion (ROM) and external to internal rotation muscle strength ratio of workers. Purpose The purpose of this study was to compare the total rotational ROM and external to internal rotation muscle strength ratio in workers with and without SAPS. Study design A cross-sectional study Methods This study included 35 workers with SAPS and 32 workers without SAPS. The total rotational ROM were measured using Smart KEMA motion sensor, and external to internal rotation muscle strength were measured using Smart KEMA pulling sensor. Results The results showed that there were significant differences in the total rotation ROM between the groups (p<0.05). However, no significant difference was found in the external to internal rotation muscle strength ratio (p>0.05). Conclusions Assembly line workers with SAPS had limited total rotational ROM. However, the ratio of external to internal rotation muscle strength ratio was not different for workers without SAPS. These characteristics can be considered factors that should be considered in evaluating workers with SAPS and establishing a treatment plan.

Economic evaluation of synthetic ethanol production by using domestic biowastes and coal mixture

Gwak, You Ra,Kim, Ye Bin,Gwak, In Seop,Lee, See Hoon Elsevier 2018 Fuel Vol.213 No.-

<P><B>Abstract</B></P> <P>Biowastes, such as cow manure, waste paper, and wood waste, are recognized as an essential source of renewable energy, and their importance increased significantly over time. However, the insufficient supply of biowastes for commercial thermochemical conversion processes is a major problem that needs to be addressed. Therefore, the co-utilization of biowastes and coal has been developed globally. In this study, we investigated the feasibility of biowaste and coal mixtures in an ethanol conversion process. A commercial-scale thermochemical process consisting of a dual fluidized bed gasifier, compressor, tar reformer, catalytic reactor, and auxiliary facilities was used and analyzed. In particular, the effects of material costs including both transportation and collection costs of biowastes and mix percentages on the economic value of synthetic ethanol were analyzed. In addition to the limitations of biowaste collection, the scale of co-utilization processes could be a critical factor for the commercialization of converting biowaste and coal mixtures to ethanol.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biowaste-coal mixtures to synthetic ethanol conversions were investigated. </LI> <LI> The economic efficiency of synthetic ethanol process increased due to increasing final products. </LI> <LI> Mixing coal could be a solution for biowastes to energy conversion. </LI> </UL> </P>

Upper Limit of Radiation from Coalescence of Rotating Hayward Black Holes

Gwak, Bogeun,Gwak, B.,Kang, G.,Kim, C.,Kim, H.-C.,Lee, C.-H.,Lee, J.,Lee, S.,Lee, W. EDP Sciences 2018 The European Physical Journal Conferences Vol.168 No.-

<P>We review the upper limit of the gravitational radiation thermally allowed under the collision of two rotating Hayward black holes. The upper limit is dependent on the gravitational spin interaction between black holes and is useful to determine one of the parameters for consistency with Laser Interferometer Gravitational-Wave Observatory (LIGO) data.</P>

An intracellular antifreeze protein from an Antarctic microalga that responds to various environmental stresses

Gwak, Yunho,Jung, Woongsic,Lee, Yew,Kim, Ji Sook,Kim, Chul Geun,Ju, Ji-Hyun,Song, Chihong,Hyun, Jae-Kyung,Jin, EonSeon The Federation of American Societies for Experimen 2014 The FASEB Journal Vol.28 No.11

<P>The structure and function of the Antarctic marine diatom <I>Chaetoceros neogracile</I> antifreeze protein (Cn-AFP), as well as its expression levels and characteristics of the ice-binding site, were analyzed in the present study. <I>In silico</I> analysis revealed that the <I>Cn-AFP</I> promoter contains both light- and temperature-responsive elements. Northern and Western blot analyses demonstrated that both Cn-AFP transcript and protein expression were strongly and rapidly stimulated by freezing, as well as temperature and high light stress. Immunogold labeling revealed that Cn-AFP is preferentially localized to the intracellular space near the chloroplast membrane. Recombinant Cn-AFP had clear antifreeze activity. Protein-folding simulation was used to predict the putative ice-binding sites in Cn-AFP, and site-directed mutagenesis of the Cn-AFP b-face confirmed their identification.—Gwak, Y., Jung, W., Lee, Y., Kim, J. S., Kim, C. G., Ju, J.-H., Song, C., Hyun, J.-K., Jin, E. An intracellular antifreeze protein from an Antarctic microalga that responds to various environmental stresses.</P>

Drying characteristics of low rank coals in a pressurized flash drying system

Gwak, In Seop,Gwak, You Ra,Kim, Ye Bin,Lee, See Hoon THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.57 No.-

<P><B>Abstract</B></P> <P>Drying characteristics of low rank coals were examined and determined using a pressurized flash drying system which consisted of a pressurized feeder, rolled tubes (maximum of 6m), a cyclone, and a back pressure regulator. The effect of the operating conditions, such as pressure (maximum of 40bar), gas outlet temperature (maximum of 300°C), particle sizes (212–300 and 300–355μm) and residence time (maximum of 1s) on the drying ratio was investigated and analyzed. The study results show that temperature is a more effective factor than pressure. A correlation equation to predict the drying ratio of coals was suggested based on operation conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The characteristics of pressurized flash drying of low rank coal were investigated. </LI> <LI> The drying ratio mostly increased with temperatures and pressures. But the drying ratio did not increase at high pressure conditions because of increasing boiling temperature. </LI> <LI> The empirical equation to predict drying ratio was suggested as follows: <SUB> D r </SUB> = 2.82 × <SUP> R 0.63 </SUP> × <SUP> S 0.02 </SUP> × <SUP> P 0.28 </SUP> × <SUP> T 0.65 </SUP> . </LI> </UL> </P>

가압 마이크로 수송관을 이용한 저급탄의 건조 특성 연구

곽인섭 ( In Seop Gwak ),곽유라 ( You Ra Gwak ),김예빈 ( Ye Bin Kim ),이시훈 ( See Hoon Lee ) 한국공업화학회 2017 공업화학 Vol.28 No.3

지속적인 에너지 수요의 증가로 인하여 저등급 석탄이 새로운 에너지 자원으로서 인정받고 있다. 그러나 저등급 석탄의 높은 수분 함량으로 인하여 저등급 석탄의 이용 효율은 기존의 석탄 이용 플랜트들에서 이용하기에 부족하다. 따라서 저등급 석탄의 수분 함량을 낮추는 건조 공정이 요구되고 있다. 비록 다양한 건조 실험들이 진행되었으나, 고압 조건에서의 건조 특성은 크게 연구되지 않았다. 이에 본 연구에서는 높은 수분 함량을 지닌 저등급 석탄(수분 함량: 21.5 wt%)의 급속 건조 특성을 가압 마이크로 상승관을 이용하여 고찰하였다. 압력(1-40 bar), 건조 온도(200-600 ℃), 마이크로 상승관 길이(2-6 m) 등의 운전 조건 변화에 따른 저등급 석탄의 건조 특성을 분석하였다. With the continuous increase of energy demand, low-grade coal is regarded as one of new energy sources. However, due to the high water content, the utilization efficiency of low-grade coal is not good to be used in recent conversion plants. Therefore, it requires a drying process to lower the water content in low-grade coals. Although a variety of drying experiments were conducted, drying characteristics in accordance with the pressure change has not been progressed. In this study, the flash drying characteristics of low grade coal with high moisture content (21.5 wt%) were determined in a pressurized micro- riser. The effect of operation conditions such as pressure (1-40 bar), dryer temperature (200-600 ℃), and tube length (2-6 m) on drying ratios were investigated.

Effect of Vehicles and Enhancers on the in vitro Skin Penetration of Aspalatone and Its Enzymatic Degradation Across Rat Skins

Gwak, Hye-Sun,Chun, In-Koo The Pharmaceutical Society of Korea 2001 Archives of Pharmacal Research Vol.24 No.6

The feasibility of skin penetration was studied for aspalatone (AM, acetylsalicylic acid maltol ester), a novel antithrombotic agent. In this studys hairless mouse dorsal skins were used as a model to select composition of vehicle and AM. Based on measurements of solubility and partition coefficient, the concentration of PC that showed the highest flux for AM across the hairless mouse skin was found to be 40%. The cumulative amount permeated at 48 h, however, appear inadequate, even when the PC concentration was employed. To identify a suitable absorption enhancer and its optimal concentration for AM, a number of absorption enhancers and a variety of concentration were screened for the increase in transdermal flux of AM. Amongst these, linoleic acid (LOA) at the concentration of 5% was found to have the largest enhancement factor (i.e., 132). However, a further increase in AM flux was not found in the fatty acid concentration greater than 5%, indicating the enhancement effect is in a bell-shaped currie. In a study of the effect of AM concentration on the permeation, there was no difference in the permeation rate between 0.5 and 1% for AM, below its saturated concentration. At the donor concentration of 2%, over the saturated condition, the flux of AM was markedly increased. A considerable degradation of AM was found during permeation studies, and the extent was correlated with protein concentrations in the epidermal and serosal extracts, and skin homogenates. In rat dorsal skins, the protein concentration decreased in the rank order of skin homogenate > serosal extract > epidermal extract. Estimated first order degradation rate constants were $6.15{\pm}0.14,{\;}0.57{\pm}0.02{\;}and{\;}0.011{\pm}{\;}0.004{\;}h^{-1}$ for skin homogenate, serosal extract and epidermal extract, respectively. Therefore, it appeared that AM was hydrolyzed to some extent into salicylmaltol by esterases in the dermal and subcutaneous tissues of skin. taken together, our data indicated that transdermal delivery of AM is feasible when the combination of PC and LOA is used as a vehicle. However, since AM is not metabolically stable, acceptable degradation inhibitors may be nervessary to fully realize the transdermal delivery of the drug.

Weakened Flexural Strength of Nanocrystalline Nanoporous Gold by Grain Refinement

Gwak, Eun-Ji,Kim, Ju-Young American Chemical Society 2016 Nano letters Vol.16 No.4

<P>High density of grain boundaries in solid materials generally leads to high strength because grain boundaries act as strong obstacles to dislocation activity. We find that the flexural strength of nanoporous gold of grain size 206 nm is 33.6% lower than that of grain size 238 mu m. We prepared three gold-silver precursor alloys, well-annealed, prestrained, and high-energy ball-milled, from which nanoporous gold samples were obtained by the same free-corrosion dealloying process. Ligaments of the same size are formed regardless of precursor alloys, and microstructural aspects of precursor alloys such as crystallographic orientation and grain size is preserved in the dealloying process. While the nanoindentation hardness of three nanoporous golds is independent of microstructural variation, flexural strength of nanocrystalline nanoporous gold is significantly lower than that of nanoporous golds with much larger grain size. We investigate weakening mechanisms of grain boundaries in nanocrystalline nanoporous gold, leading to weakening of flexural strength.</P>