• Current Applied Physics
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• 제18권11호
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• pp.1426-1430
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• 2018

High magnetic field effects on the microstructure and magnetic properties of $BaFe_{12}O_{19}$ hexaferrites synthesized hydrothermal method have been investigated. The obtained results indicate that the lattice constant decreases gradually as the magnetic field strength increases, which may be attributed to the lattice distortion resulted from the high magnetic field. Polycrystalline $BaFe_{12}O_{19}$ samples prepared under magnetic field strength at zero and 5 T are single phase. It is found that application of external magnetic field during synthesis can induce orientated growth of the hexaferrite crystals along the easy magnetic axis. The magnetic properties can be effectively regulated by an application of high magnetic fields. It is observed that the $BaFe_{12}O_{19}$ prepared under a 5 T magnetic field exhibits a higher room-temperature saturation magnetization (66.3 emu/g) than that of the sample (43.6 emu/g) obtained without magnetic field. The results can be explained as the enhanced crystalline, improvement of $Fe^{3+}$ ions occupancy and the oriented growth induced by the external magnetic field. The growing orientation of particles gives rise to increased coercivity due to the enhancement in shape anisotropy. It is expected that an application of magnetic field during the formation of magnetic nanoparticles could be a promising technique to modify magnetic properties with excellent performance.

• Composites Research
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• 제34권1호
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• pp.70-75
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• 2021

본 논문은 단섬유 칩으로 구성된 Sheet Molding Compound(SMC) 복합재료를 실험적으로 관찰된 특징들을 바탕으로 메소스케일(meso-scale) 대표체적요소(RVE: Representative Volume Element)를 재구성하는 새로운 알고리즘을 제시한다. 전산해석을 이용하여 SMC 복합재료의 비등방성 거동의 정확한 예측은 어려운 문제이다. 이를 극복하기 위해, SMC 복합재료를 위한 일련의 이미지 프로세싱 기술과 재구성 알고리즘 및 유한요소(FE: Finite Element) 생성기로 구성된 SMC RVE 모델을 개발하였다. 첫째, micro-CT 이미지 프로세싱은 SMC 물성에 직접적인 상관관계를 가지는 섬유칩의 배향 및 분산의 확률적 분포를 평가한다. 둘째, 해당 통계적 분포를 바탕으로 섬유칩 간의 겹침효과를 고려한 섬유칩 팩킹 재구성 알고리즘을 개발한다. 마지막으로, SMC 복합재료 멀티스케일 해석을 이용하여 매크로스케일(macro-scale)에서의 거동을 파악하고 실험데이터를 통해 검증을 수행한다.

• 한국재료학회지
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• 제31권6호
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• pp.325-330
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• 2021

Bi₂MoO₆ (BMO) via the structure-directing role of CO(NH₂)₂ is successfully prepared via a facile solvothermal route. The structure, morphology, and photocatalytic performance of the nanoflake BMO are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectrum analysis (PL), UV-vis spectroscopy (UV-vis) and electrochemical test. SEM images show that the size of nanoflake BMO is about 50 ~ 200 nm. PL and electrochemical analysis show that the nanoflake BMO has a lower recombination rate of photogenerated carriers than particle BMO. The photocatalytic degradation of tetracycline hydrochloride (TC) by nanoflake BMO under visible light is investigated. The results show that the nanoflake BMO-3 has the highest degradation efficiency under visible light, and the degradation efficiency reached 75 % within 120 min, attributed to the unique hierarchical structure, efficient carrier separation and sufficient free radicals to generate active center synergies. The photocatalytic reaction mechanism of TC degradation on the nanoflake BMO is proposed.

• The Journal of Korean Physical Therapy
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• 제34권5호
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• pp.212-217
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• 2022

Purpose: This study sought to investigate the effects of visual cue deprivation balance training by applying head control feedback to the balance function and the fall index in older people. Methods: The study was conducted on 26 older people at the S Hospital in Gyeongsansi. The patients were randomly divided into the experimental groupI (EGI, n=9), the experimental groupII (EGII, n=9), and the control group (CG, n=8). The three groups were trained for 30 minutes three times a week for four weeks. To assess the patients' static balance function, their limits of stability (LOS) was measured using the BioRescue system, (RM Ingenierie, France), composed of a pressure platform that can measure force in diverse ways, a computer, and a monitor. The dynamic balance function was measured using the Berg Balance Scale (BBS). Also, the fall index was measured to evaluate the risk of falling. A paired t-test was performed to compare pre- and post-training performance within the groups. One-way ANOVA was performed for comparing the three groups. A post hoc least significant difference (LSD) test was also performed. Results: The results of the LOS showed a significant difference after training in the EGI and EGII groups (p<0.05). As a result of the difference between the three groups, there was a significant difference after training (p<0.05). The results of the BBS showed a significant difference after training in the EGI group (p<0.05). As a result of the difference between the three groups, there was a significant difference after training (p<0.05). Conclusion: Visual cue deprivation balance training applying head control feedback is effective in improving the dynamic balance function in older people. It is also necessary to constantly maintain the head orientation by feedback and to properly control the head movement.

• Steel and Composite Structures
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• 제42권4호
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• pp.427-446
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• 2022

Cutouts in the beams or plates are often unavoidable due to inspection, maintenance, ventilation, structural aesthetics purpose, and sometimes to lighten the structures. Therefore, there will be a substantial reduction in the strength of the structure due to the introduction of the cutouts. However, these cutouts can be reinforced with the different patterns of ribs (stiffener) to enhance the strength of the structure. The present study highlights the influence of the elliptical cutout reinforced with a different pattern of ribs on the stability performance of such stiffened composite panels subjected to non-uniform edge loads by employing the Finite element (FE) technique. In the present formulation, a 9-noded heterosis element is used to model the skin, and a 3-noded isoparametric beam element is used to simulate the rib that is attached around a cutout in different patterns. The displacement compatibility condition is employed between the plate and stiffener, and arbitrary orientations are taken care by introducing respective transformation matrices. The effect of shear deformation and rotary inertia are incorporated in the formulation. A new mesh configuration is developed to house the attached ribs around an elliptical cutout with different patterns. Initially, a study is performed on the panels with different stiffener schemes for various ply orientations and for different stiffener depth to width ratios (d_s/b_s) to determine an optimal stiffener configuration. Further, various parametric studies are conducted on an obtained optimal stiffened panel to understand the effect of cutout size, cutout orientation, panel aspect ratio, and boundary conditions. Finally, from the analysis, it can be observed that the arrangement of the stiffener attached to a panel has a major impact on the buckling capacity of the stiffened panel. The stiffener's depth to width ratio also significantly influences the buckling characteristic.

• 인간식물환경학회지
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• 제24권3호
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• pp.277-283
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• 2021

Background and objective: This study was conducted to increase understanding of agriculture through agricultural experience programs for adolescents living in self-reliance residence hall, and to investigate changes in work performance ability through changes in hand function. Methods: There were 11 subjects, and the average age was 18.2 years, all males without disabilities. The agricultural experience program consists of a total of 10 sessions including orientation and watching videos on future agriculture, creating vegetable gardens, planting, managing each crop, harvesting, visiting the processing room, and selling at a local food store. Results: The change in agricultural literacy by the agricultural experience program positively improved from a score of 113.73 to 127.91 (p = .008). The changes by sub-item are as follows. The value and safety of agri-foods (p = .020) and agriculture and natural environment (p = .007) were significantly improved. The function and value of rural areas (p = .050), production of agricultural products (p = .160), processing and distribution of agricultural products (p = .248), and agricultural policies (p = .058) were not significantly changed. The simple function of the hands was measured by the number of pegs inserted during 30 seconds, and the assembly function was measured by the number of pegs inserted during 60 seconds. In the case of simple function, the dominant hand was improved from 14.82 to 15.83 (p = .014), andthe non-dominant hand was also significantly improved from 13.79 to 15.01 (p = .002). There was no significant improvement in the simple function (p = .153) and assembly function (p = .770) of both hands. Conclusion: It is considered that the agricultural experience program will enable youths living in self-reliance residence halls to enhance their understanding of agriculture as an occupation, and enable them to play a role as wise consumers by positively affecting improvements in their agricultural literacy and simple hand functions.

• Asia Marketing Journal
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• 제20권1호
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• pp.23-48
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• 2018

SK group has been a pioneer in overall brand management and, more recently, in CSR-imbedded brand management. SK vision of "improving itself to give greater happiness to all of its customers" and the symbol mark of "Wings of Happiness" are some good examples of integrating distinct brand identities of various member companies. After impressive growth and expansions into diverse business areas, SK group is ranked as the third largest company based on asset amounts according to the Fair Trade Commission of Korea, only after Samsung and Hyundai Motor groups. SK brand management can be analyzed, using the framework of 4 stages - 'infrastructure', 'planning', 'doing', and 'seeing' stages. In order to secure 'infrastructure' of brand management system, SK has invested huge resources to the 'SK BMS' (SK Brand Management System). At the 'planning' stage, the most important task of SK like other Korean business groups is perhaps to adopt a well-organized 'brand identity (BI) system' which may consolidate brand values of individual member companies. In actuality, SK BI consists of Customer Happiness located at the center and 3 other elements of Pride, Professionalism, and Customer-orientation. At the 'doing' stage, the slogan of 'OK! SK' and the logo of 'Wings of Happiness' have been placed at the core of the SK group brand building programs. SK adopts the principle of 'independent yet united', pinpointing that each member company independently works for its business performance but it is, at the same time, encouraged to integrate its capabilities for the SK group brand. In addition, SK has sought 'shared growth' with business partners for happiness for all the members in the society. 'Social Contribution Philosophy' based on SK value of 'creation of greater happiness' is again one of the most important guidelines for CSR (corporate social responsibility) at the doing stage. At the seeing stage, SK regularly evaluates its branding programs. SK has shown some very impressive achievements in brand management: (1) a core identity of 'Customer Happiness' participating member companies may share, (2) harmonious relationships between the group brand management office and brand management divisions of member companies, and (3) consistency-keeping in brand management over time. However, there remain two major challenges: (1) globalization of SK and (2) reinforcing sustainable superiority over not only Korean rivals but also global ones.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.260-264
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• 2012

We have investigated the effect of ambient gases on the structural, electrical, and optical characteristics of IZO thin films intended for use as anode contacts in the organic light emitting diodes (OLED) devices. These IZO thin films were deposited on the PES film by radio frequency (RF) magnetron sputtering under different ambient gases (Ar, Ar + O2, and Ar + H2) at room temperature. In order to investigate the influences of the ambient gases, the flow rate of oxygen and hydrogen in argon has been changed from 0.1 sccm to 0.5 sccm, respectively. All the IZO thin film has an (222) preferential orientation regardless of ambient gases. The electrical resistivity of the IZO film increased with increasing O2 flow rate, whereas the electrical resistivity decreased sharply under an Ar + H2 atmosphere and was nearly similar regardless of the H2 flow rate. The change of electrical resistivity with changes in the ambient gas composition was mainly interpreted in terms of the charge carrier concentration rather than the charge carrier mobility. All the films showed the average transmittance over 85% in the visible range. The OLED device was fabricated with different IZO substrates made with the configuration of IZO/α-NPD/DPVB/Alq3/LiF/Al in order to elucidate the performance of the IZO substrate. The current density and the luminance of OLED devices with IZO thin films deposited in 0.5 sccm H2 ambient gas are the highest amongst all other films.

• 대한토목학회논문집
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• 제29권6D호
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• pp.771-779
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• 2009

GIS의 자료기반이 되는 수치지도는 주로 재래식 항공사진측량에 의해서 제작되고 있다. 따라서 촬영된 아날로그 항공사진은 필름의 현상, 인화, 스캐닝 작업 과정을 거쳐 수치지도 제작에 이용되고 있다. 하지만 디지털 항측카메라의 개발로 촬영된 사진의 전처리과정 없이 직접 디지털 영상의 획득이 가능하여 항공사진의 효율성이 극대화 되고 있는 실정이다. 본 연구 에서는 면형방식 카메라인 DMC(Digital Modular Camera) 영상의 블록구성에 따른 기하적 안정성을 검증하기 위하여 횡스트립의 유무, GPS/INS 외부표정요소의 유무 및 지상기준점 수를 달리한 조건으로 블록조정을 수행하였다. 각 조건별 블록조정의 결과로 부터 외부표정요소에 대한 잔차의 변화를 계산하여 정확도를 상호 비교하였다. 연구 결과 횡스트립 추가 시 블록은 기하학적으로 약 30% 안정함을 알 수 있었고, 외부표정요소에서는 횡스트립 추가 시 표준편차의 평균에서 X축으로 2cm, Y축으로 3cm, Z축으로 3cm 더 우수하였으며, omega는 6", phi는 4", kappa는 3" 더 우수하게 나타났다.

• 한국응용과학기술학회지
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• 제40권5호
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• pp.1043-1054
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• 2023

비건 화장품 시장이 급성장하는 가운데, 소비자의 환경 및 윤리적 가치 지향이 강화되고 있지만, 이에 관한 연구는 제한적이다. 본 연구는 비건 화장품의 구매의도에 영향을 주는 소비자의 가치 인식과 환경 동기, 그리고 지각된 장벽 간의 관계를 분석하였다. 300명의 비건화장품 사용 경험이 있는 여성을 대상으로 PLS-SEM 분석을 진행한 결과, 금전적 가치, 사회적 가치, 브랜드 가치, 감정적 가치, 품질 가치, 그리고 환경 지식이 구매의도에 큰 영향을 주는 것으로 확인되었다. 조절 효과 분석에서는 이미지 장벽과 가치 장벽이 중요한 요인으로 나타났다. 중요도-성능 지도 분석을 통해, 감정적 가치가 비건 화장품의 구매의도를 강화하는 전략적 결정에 중요한 핵심 요인으로 드러났다. 본 연구는 비건 화장품 시장의 경쟁력 강화와 지속 가능한 소비 태도 활성화에 대한 이론적 및 실무적 기여를 제공한다.