• Carbon letters
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• 제24권
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• pp.82-89
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• 2017

In this study, composite PAN-based ACNFs embedded with MgO and $MnO_2$ were prepared by the electrospinning method. The resultant pristine ACNFs, ACNF/MgO and $ACNF/MnO_2$ were characterized in terms of their morphological changes, SSA, crystallinity and functional group with FESEM-EDX, the BET method, XRD and FTIR analysis, respectively. Results from this study showed that the SSA of the ACNF/MgO composite ($1893m^2g^{-1}$) is significantly higher than that of the pristine ACNFs and $ACNF/MnO_2$ which is 478 and $430m^2g^{-1}$, respectively. FTIR analysis showed peaks of 476 and $547cm^{-1}$, indicating the presence of MgO and $MnO_2$, respectively. The FESEM micrographs analysis showed a smooth but coarser structure in all the ACNFs. Meanwhile, the ACNF/MgO has the smallest fiber diameter ($314.38{\pm}62.42nm$) compared to other ACNFs. The presence of MgO and $MnO_2$ inside the ACNFs was also confirmed with EDX analysis as well as XRD. The adsorption capacities of each ACNF toward $CH_4$ were tested with the volumetric adsorption method in which the ACNF/MgO exhibited the highest $CH_4$ adsorption up to $2.39mmol\;g^{-1}$. Meanwhile, all the ACNF samples followed the pseudo-second order kinetic model with a $R^2$ up to 0.9996.

• 대한치과교정학회지
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• 제46권4호
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• pp.220-227
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• 2016

Objective: The aim of this study was to translate the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) into Turkish, validate the questionnaire, and provide a cross-cultural adaptation. Methods: The translation process included the following steps, which were performed by a translation committee: (1) translation into Turkish, (2) back translation into English, (3) pretesting, and (4) cross-cultural adaptation. The Turkish version of the PIDAQ was produced subsequent to the translation process. Validity and reliability were measured using the Perception of Occlusion Scale and the aesthetic component of the Index of Orthodontic Treatment Need. The questionnaire was administered to 260 individuals (age range, 18-30 years; mean age, $20.50{\pm}1.9$ years). Structural validity was assessed via factor analysis, and internal consistency was measured using Cronbach's alpha coefficient. Results: Factor analysis revealed a four-factor structure, with factor loadings for included items ranging from 0.380 to 0.868. Few questions were shuffled among domains various factor loadings. Cronbach's alphas for the Turkish version of the PIDAQ ranged from 0.534 to 0.904. Mean scores for the PIDAQ subscale and total scores differed significantly according to Index of Orthodontic Treatment Need and Perception of Occlusion Scale scores. Conclusions: This study provided a Turkish version of the PIDAQ, which could be a useful tool in the evaluation of the psychosocial impact of malocclusion in young Turkish adults.

• 한국세라믹학회지
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• 제52권4호
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• pp.237-242
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• 2015

$Bi_{0.5}(Na_{0.78}K_{0.22})_{0.5}TiO_3$ (BNKT) lead-free piezoelectric ceramics modified by $LaMnO_3$ (LM) were fabricated by conventional solid-state method. The crystal structure and the morphology of the lead free ceramics were analyzed by XRD (X-ray diffraction) and FE-SEM (Field Emission Scanning Electron Microscopy). The LM modified BNKT ceramics have a phase transition from ferroelectric tetragonal to non-polar pseudo-cubic. Despite decreases in the remnant polarization ($P_r$) and coercive field ($E_c$) in the P-E hysteresis loops, the electric-field induced strain properties were significantly enhanced by the LM modification. The highest value of $S_{max}/E_{max}=412pm/V$ at an applied electric field of 5 kV/mm was found in BNKT-0.01LM ceramic.

• 대한치과교정학회지
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• 제43권4호
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• pp.160-167
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• 2013

Objective: To evaluate the shapes and sizes of nasopharyngeal airways by using cone-beam computed tomography and to assess the relationship between nasopharyngeal airway shape and adenoid hypertrophy in children. Methods: Linear and cross-sectional measurements on frontal and sagittal cross-sections containing the most enlarged adenoids and nasopharyngeal airway volumes were obtained from cone-beam computed tomography scans of 64 healthy children ($11.0{\pm}1.8$ years), and the interrelationships of these measurements were evaluated. Results: On the basis of frontal section images, the subjects' nasopharyngeal airways were divided into the following 2 types: the broad and long type and the narrow and flat type. The nasopharyngeal airway sizes and volumes were smaller in subjects with narrow and flat airways than in those with broad and long airways (p < 0.01). Children who showed high adenoid-nasopharyngeal ratios on sagittal imaging, indicating moderate to severe adenoid hypertrophy, had the narrow and flat type nasopharyngeal airway (p < 0.01). Conclusions: Cone-beam computed tomography is a clinically simple, reliable, and noninvasive tool that can simultaneously visualize the entire structure and a cross section of the nasopharyngeal airway and help in measurement of adenoid size as well as airway volume in children with adenoid hypertrophy.

• 한국전자파학회논문지
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• 제29권5호
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• pp.325-335
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• 2018

본 논문에서는 이동체의 움직임 및 그에 따른 편파 도래각 변화에 대응 가능한 위성 수신용 능동 위상 배열 안테나를 개발하도록 한다. 이를 위하여 이중편파를 10.7~14.5 GHz의 Ku 대역에서 동시에 구현 가능한 비발디 안테나와 효과적으로 위상 및 이득을 제어할 수 있는 MFC(Multi-Function Core) 칩을 자체 개발하였으며, 이를 이용하여 수신 모듈과 제어 모듈로 이루어진 능동 위상 배열 안테나를 제작하였다. 제작 결과, $60^{\circ}$ 각도까지의 깨끗한 빔 조향 특성과 높은 격리도의 편파 가변 특성을 확인하였다.

• 센서학회지
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• 제16권1호
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• pp.17-23
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• 2007

This paper presents a miniaturized turn-counting sensor (TCS) where the geomagnetism and high-rpm rotation of ammunition are used to detect the turn number of ammunition for applications to small-caliber turn-counting fuzes. The TCS, composed of cores and a coil, has a robust structure with no moving part for increasing the shock survivability in the gunfire environments of ${\sim}30,000$ g's. The TCS is designed on the basis of the simulation results of an electromagnetic analysis tool, $Maxwell^{(R)}$3D. In experimental study, the static TCS test using a solenoid-coil apparatus and the dynamic TCS test (firing test) have been made. The presented TCS has shown that the induction voltage of $6.5{\;}mV_{P-P}$ is generated at the magnetic flux density of 0.05 mT and the rotational velocity of 30,000 rpm. From the measured signal, the TCS has shown the SNR of 44.0 dB, the nonlinearity of 0.59 % and the frequency-normalized sensitivity of $0.26{\pm}0.01{\;}V/T{\cdot}Hz$ in the temperature range of $-30{\sim}+43^{\circ}C$. Firing test has shown that the TCS can be used as a turn-counting sensor for small-caliber ammunition, verifying the shock survivability of TCS in high-g environments.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2002년도 학술대회지
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• pp.207-212
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• 2002

우리나라에서 건설산업의 구조개편, 건설기술의 경쟁력 향상 등과 맞물려 CM에 대한 다양한 논의과정이 있었으며 건설산업기본법('97) 및 건설기술관리법('01)에 CM제도가 규정됨으로써 명실상부하게 체계를 갖추게 되었다. 이 중 특히 공공사업에 대해서는 효율성 제고라는 문제의식에서 출발하여 제도의 활성화를 위한 시범사업(Pilot Project)이 정부를 중심으로 추진중에 있다. 현재 추진중인 시범사업은 제도의 정착, 활성화 뿐만아니라 기존의 CM제도를 좀더 구체화하고 다양화하는 과정으로서 그 시행의 중요성을 인식할 수 있을 것이다. 이러한 시범사업의 추진을 통하여 현재의 감리중심의 CM제도에서 발주자 및 사업특성을 고려할 수 있도록 Owner형 CM, PM형, 민자사업 적용방안 등 다양한 CM적용형태를 모색해야 할 것이다. 이러한 노력들은 공공사업의 효율성 제고 뿐만아니라 민간부분에도 많은 영향을 미칠 것으로 기대된다.

• 한국융합학회논문지
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• 제8권8호
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• pp.197-202
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• 2017

본 연구는 미라 모발에 존재하는 멜라닌과립의 보존 상태와 모양을 규명하기 위해서 1250kV의 초고압전자현미경(high voltage electron microscope: HVEM)을 사용하여 3차 구조를 분석하였다. 미라 모발에서 피질에 분포하고 있는 멜라닌과립은 큐티클층에 인접한 바깥쪽 피질에 집중적으로 분포하고 있다. 이들 부위에는 다량의 멜라닌과립들이 무리를 지어 존재하고 있어서 현대인의 정상 모발에 있는 멜라닌과립의 분포양상과 뚜렷한 차이점을 나타내었다. 초고압전자현미경으로 ${\pm}60$도의 범위에서 1도 간격으로 촬영한 결과 멜라닌과립은 길쭉한 타원형의 형태로 크기가 다양하게 관찰되었다. 과립의 크기는 단축 직경이 $0.3-0.6{\mu}m$이고, 장축 직경은 $0.5-1{\mu}m$로 측정되었다. 결론적으로 초고압전자현미경은 일반 투과전자현미경보다 높은 해상도와 투과력을 가져서 두꺼운 절편의 생물 시료 구조분석에 용이하다.

• Journal of Nutrition and Health
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• 제29권10호
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• pp.1059-1071
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• 1996

This study was performed to investigate the effect of dietary protein level on renal senescence. Male rats of 337.8$\pm$5.7g body weight were underlateral nephrectomy or shamoperation. The rats were divided into high protein(40% casein), normal protein(15% casein) and low protein(8% casein)diets and fed experimental diets ad libitum for 24 weeks. The results are summarized as follows. There was a hypertophy of the remnant kidney of uninephrectomized rats of 40% or 15% protein group, coming up to the comparable weights of both kidneys of sham-operated rats. However, the hypertrophic effect was not seen in uninephrectomized rats of 8% protein group. Serum albumin was lower in uninephrectomized rats. With increasing dietary protein level blood urea nitrogen was increased, whereas, urinary urea nitrogen excretion was decreased. Urinary solute excretion was higher in uninephrectomized group than in sham-operated group. However, effect of dietary protein level on urinary solute excretion varied dpending on th solutes tested. GFR and urinary protein excretion, throughout experiment, increased with feeding period and with dietary protein level. Proteinuria was most severe in uninephrectomized rats fed 40% casein diet. Maximum urine concentration ability measured after dehydration was not different among the experimental groups. Light microscopic examination showed focal segmental glomerulosclerosis and mild increas of glomerular mesangial matrix in uninephrectomized rats fed 40% and 15% protein diet, however, which was not observed in uninephrectomized rats fed 8% protein diet and in sham-operated rats fed 40% diet. Immunofluorescence studies revealed segmental deposits of albumin in the mesangium and capillary loops in high protein and uninephrectomized groups. Minimal granular deposition of IgG was noted in the mesangium of all experimental groups. In conclusion, high protein intake accelerated deterioration of renal function and it was correlated with morphological change. Low protein intake was effective in preventing these changes.

• 센서학회지
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• 제26권3호
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• pp.179-185
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• 2017

This article describes the characteristics of nondispersive infrared carbon dioxide gas sensor according to the temperatures and humidifies. In this researches, a thermopile sensor that included application-specific integrated circuit (ASIC) was used and the White-cell structure was implemented as an optical waveguide. The developed sensor modules were installed in gas chamber and then the temperature of gas chamber has been increased from 283 K to 313 K with 10K temperature step. In order to analyze the effects of humidity levels, the relative humidity levels were changed from 30 to 80%R.H. with small humidifier. Then, the characteristics of sensor modules were acquired with the increment of carbon dioxide concentrations from 0 to 2,000 ppm. When the initial voltages of sensors were compared before and after humidifying the chamber at constant temperature, the decrements of the output voltages of sensors are like these: 9mV (reference infrared sensor), 41 mV (carbon dioxide sensor), 2 mV (temperature sensor). With the increment of ambient temperature, the averaged output voltage of carbon dioxide sensor was increased 19 mV, however, when the humidity level was increased, it was decreased 14mV. Based upon the experimental results, the humidity effect could be alleviated by the increment of temperature, so the effects of humidity and temperature could be only compensated by the ambient temperature itself. The estimated carbon dioxide concentrations showed 10% large errors below 200 ppm, however, the errors of the estimations of carbon dioxide concentrations were less than ${\pm}5%$ from 400 to 2,000 ppm.