• Current Photovoltaic Research
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• v.10 no.4
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• pp.101-106
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• 2022

We prepared a CsPbI₂Br solution using Cesium iodide (CsI), Lead (II) bromide (PbBr₂) and Lead (II) iodide (PbI₂) materials into a polar solvent mixture of N,N-dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO). A simple spin coating technique was used for the fabrication of CsPbI₂Br absorber layer in the solution process. In order to prepare uniform coating of absorber film we adopted a hot-air process in assocation with the spin coating. It was confirmed that the thin film manufactured by the hot-air process had a higher absorption rate than that without it, and the optical band gap was measured 1.93 eV. The thin film of absorber was uniformly prepared and revealed the Black α-Cubic crystal phase as proved through X-ray diffraction analysis. Finally, a perovskite solar cell having an n-i-p structure was manufactured with a CsPbI₂Br perovskite absorption layer. From the solar cell, we obtained a power conversion efficiency (PCE) of 5.97% in a forward measurement.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.281-286
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• 2023

This paper proposes a design of a wideband array antenna involving the downlink bands of fixed satellite service (FSS) and broadcasting satellite service (BSS) by applying two mixed patch sets. The proposed antenna is implemented on FR4 substrate by arranging rectangular patches in 6 by 2. To design a wideband antenna (10.7~12.75 GHz) covering both FSS downlink bands (10.7~10.95 GHz, 11.2~11.45 GHz) and BSS downlink bands (11.7~12.5 GHz, 12.2~12.75 GHz, 11.7~12.2 GHz), rectangular patches working at 11.5 GHz and 12.5 GHz are arranged alternately, and thus the proposed antenna can obtain a wide bandwidth equivalent to 30.8% of the center frequency. The proposed antenna was fabricated and measured, and the results are well matched with the simulated ones. From the performances, the proposed antenna can be applied to the receiving antenna for FSS and BSS downlinks.

• Journal of the Korean institute of surface engineering
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• v.56 no.2
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• pp.137-146
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• 2023

Nanosized TiO₂ has been widely investigated in photoelectrochemical or photocatalytic applications due to their intrinsic properties such as suitable band position, high photocorrosion resistance, and surface area. In this study, to achieve the high efficiency in photoelectrochemical and photocatalytic performance, TiO₂ nanotubular structures were formed by anodization at various temperatures and times. The morphological and crystal structure of the anodized TiO₂ nanotubes (NTs) were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The photoelectrochemical (PEC) properties and incident photon-to-current conversion efficiency (IPCE) of the TiO₂ NTs were studied with different lengths and morphologies. From the detailed investigations, the optimum thickness of TiO₂ nanotubes was 3 ㎛. Moreover, we found that the optimum photocatalytic pollutant removal efficiency of TiO₂ nanotubes for photodegradation of Rhodamine B (RhB) under simulated solar light was 5.34 ㎛ of tube length.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4708-4714
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• 2022

The novelty in the present search, the Soda-Lime-Silica (SLS) glass waste to prepare free lead glass shielding was used in order to limit the accumulation of glass waste, which requires extensive time to decompose. This also saves on the consumption of pure SiO₂, which is a finite resource. Furthermore, the combining of BaO with Bi₂O₃ into a glass network leads to increased optical properties and improved attenuation. The UV-Visible Spectrophotometer was used to investigate the optical properties and the radiation shielding properties were reported for current glass samples utilizing the PhysX/PDS online software. The optical property results indicate that when BaO content increases in glass structure, the Urbach energy ΔE, and refractive index n increases while the energy optical band gap E_opt decreases. The result of the metallisation criteria (M) revealed that the present glass samples are nonmetallic (insulators). Furthermore, the radiation shielding parameter findings suggest that when BaO was increased in the glass structure, the linear attenuation coefficient and effective atomic number (Z_eff) rose. But the half-value layer HVL declined as the BaO concentration grew. According to the research, the glass samples are non-toxic, transparent to visible light, and efficient radiation shielding materials. The Ba5 sample is considered the best among all the samples due to its higher attenuation value and lower HVL and MFP values, which make it a suitable candidate as transparent glass shield shielding.

• Journal of dental hygiene science
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• v.23 no.1
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• pp.1-12
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• 2023

Background: This study aimed to identify the present level and needs of clinical dental hygienists and to present the Borich needs assessment and the locus for focus model as integrated priorities. Methods: The participants of this study were dental hygienists working in dental clinics (hospitals). The final data of the 194 participants were analyzed using frequency analysis and a paired sample t-test. To analyze the need for clinical dental hygienists to perform work, the Borich priority determination formula was used. The x-y plane consisting of four quadrants was used to analyze the need using the locus for focus model, which helps to determine the priority while showing visual effects. Results: "Scaling" was the highest required level for clinical dental hygienists, and "panorama taking" was the highest present level. The priorities of educational needs were systematically and visually derived from dental hygienists who were currently working through the Borich needs assessment and the locus for focus model for each task performed in the clinical field. Through the priorities of these two models, a total of 13 items appeared in the common high-level area; "oral health care (disability)," "oral health care (systemic disease)," "applying a rubber dam," "professional mechanical tooth cleaning," "root planing," "taking vital signs," "medication counseling," "wire cutting," "removing cement after removing band/bracket," "delivering bracket," "preparing mini-screw implantation," "dental insurance claim," and "patient reception." Conclusion: Based on the results, the department of dental hygiene should maintain and improve the standardized clinical practice curriculum and clinical dental hygienists' practical skills and contribute to the realization of the legal scope of dental hygienists, reflecting the requirements of clinical fields.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.11-11
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• 2021

2018년부터 삼척지역에는 전파강수관측소(X-band 이중편파레이더)가 설치되어 현업 운영 중에 있다. 해당 지역은 영동지역은 산지로 둘러싸여 있어 지형적인 여건으로 지상강우관측망과 기존 대형 강우레이더로도 정확한 강우관측에 한계가 있었다. 설치 이후 전파강수관측소의 품질관리와 최적 관측전략 수립, 분포형 비차등위상차 기반의 강우추정 기법의 적용으로 정량적 추정강우의 정확도가 확보되어 75m의 고해상도 격자강우 정보가 제공되고 있다. 본 연구에서는 이러한 전파강수관측소의 정량적 추정강우를 홍수예보에 활용하기 위해서 강우기반의 하천 수위 예측 기법인 하천흐름계산도표를 개발하였다. 하천흐름계산도표가 개발된 지역은 삼척 전파강수관측소의 관측 반경에 포함되는 삼척오십천 유역이며, 해당지역은 수변공원으로 조성되어 있어 시민의 접근이 용이하여 하천 수위 급상승으로 인해 피해가능성이 높은 지역이다. 2019년과 2020년 호우사례를 대상으로 개발된 하천흐름계산도표에 전파강수관측소의 정량적 추정강우를 적용하여 하천수위 상승 예측성을 평가하였다. 또한 비교대상으로 강우관측소 강우자료와 환경부 대형 강우레이더 강우자료의 적용결과를 함께 비교하였다. 비차등 위상차 기반의 강우추정 기법을 적용하여 산정된 삼척 전파강수관측소의 정량강우는 기존의 강우추정 결과(SRI, CMP_HFC)보다 강우추정 정확도가 향상된 것을 확인하였다. 특히, 10km 관측 반경을 기준으로 분석하면 정확도가 상대적으로 높았다. 삼척 전파강수관측소 추정강우를 하천흐름 계산도표에 적용한 결과, 2020년 9월 7일 호우에 의해 삼척오십천 유역에서 관심수위 초과(10:20), 주의수위 초과(11:20)가 발생하였는데, 삼척 전파강수관측소 추정강우가 관심수위 초과 1시간 50분 전에 수위상승을 예측하였고, 주의수위 초과 30분전에 수위상승을 예측하였다. 이를 통해 개발된 하천흐름계산도표와 삼척 전파강수관측소의 홍수예보 활용 가능성을 확인하였다.

• Analytical Science and Technology
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• v.20 no.5
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• pp.406-412
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• 2007

The formation of inclusion complexes between ${\beta}$-cyclodextrin and diethylenetriamine substituted-pyridine copper(II) perchlorate; [Cu(dien)(sub-py)] $(ClO_4)_2$, were studied by spectrophotometric methods. On account of charge-transfer band(MLCT) and $^2T_2{\rightarrow}^2E$, the two high peaks were observed as an inclusion complex for the [${\beta}$-CD]$[Cu(dien)(p-Cl-py)]^{2+}$ in the ultraviolet region of the spectrum. The ${\beta}$-CD and $[Cu(dien)(sub-py)]^{2+}$ ion formed a 1:1 complex, and the formation constants were decreased with the increasing temperatures, due to weak binding energy between ${\beta}$-CD and $[Cu(dien)(sub-py)]^{2+}$ ion. This reaction was controlled by enthalpy. In a correlation of the Hammett substituent constants and formation constants for the reaction, formation constants were increased by strong binding energy in the inclusion complexes when electron donating groups were substituted in pyridine ring.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.826-837
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• 2021

Immunoglobulin G4-related disease (IgG4-RD) is a chronic inflammatory condition involving multiple organs, including the salivary or lacrimal glands, orbit, pancreas, bile duct, liver, kidney, retroperitoneum, aorta, lung, and lymph nodes. It is histologically characterized by tissue infiltration with lymphocytes and IgG4-secreting plasma cells, storiform fibrosis, and obliterative phlebitis. In the thoracic involvement of IgG4-RD, mediastinal lymphadenopathy and perilymphangitic interstitial thickening of the lung are the most common findings. Peribronchovascular and septal thickening and paravertebral band-like soft tissue are characteristic findings of IgG4-RD. Other findings include pulmonary nodules or masses, ground-glass opacity, alveolar interstitial thickening, pleural effusion or thickening, mass in the chest wall or mediastinum, and arteritis involving the aorta and coronary artery. Radiologic differential diagnosis of various malignancies, infections, and inflammatory conditions is needed. In this review, we describe the imaging findings of IgG4-RD and the radiologic differential diagnoses in the thorax.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.459-467
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• 2009

$Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were prepared on indium-tin-oxide(ITO)-coated glass substrates by using thermal evaporation. The crystallization was achieved by annealing the as-deposited films in flowing nitrogen. X-ray diffraction spectra showed that the $Cd_2GeSe_4$ and the $Cd_2GeSe_4:Co^{2+}$ films were preferentially grown along the (113) orientation. The crystal structure was rhomohedral(hexagonal) with lattice constants of $a=7.405\;{\AA}$ and $c=36.240\;{\AA}$ for $Cd_2GeSe_4$ and $a=7.43\;{\AA}$ and $c=36.81\;{\AA}$ for $Cd_2GeSe_4:Co^{2+}$ films. From the scanning electron microscope images, the $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were plated, and the grain size increased with increasing annealing temperature. The optical energy band gap, measured at room temperature, of the as-deposited $Cd_2GeSe_4$ films was 1.70 eV and increased to about 1.74 eV and of the as-deposited $Cd_2GeSe_4:Co^{2+}$ films was 1.79 eV and decreased to about 1.74 eV upon annealing in flowing nitrogen at temperatures from $200^{\circ}C$ to $500^{\circ}C$. The dynamical behavior of the charge carriers in the $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were investigated by using the photoinduced discharge characteristics technique.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.194-201
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• 2015

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by $^{137}Cs$ gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity ($R^2$ > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.