• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.30.1-30.8
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• 2019

Background: Advancements in the field of microvascular surgery and the widespread adoption of microvascular surgical techniques have made the use of osteocutaneous fibula free flaps the standard of care in the surgical management of segmental mandibular defects. Although the literature possesses abundant evidence to support the effectiveness of fibula free flaps as a reconstructive method, there are relatively few studies reporting on outcomes as objectively measured by videofluoroscopic swallowing studies (VFSS). The purpose of this study is to explore the potential correlation between early postoperative VFSS and the long-term swallowing outcomes in patients who underwent mandibular reconstruction with fibula free flaps. Methods: We performed a retrospective chart review of 36 patients who underwent mandibular reconstruction with osteocutaneous fibular free flaps between 2009 and 2012. Demographics, clinical variables, VFSS data, and diet information were retrieved. Penetration and aspiration findings on VFSS, long-term oral feeding ability, and the need for gastrostomy tube were statistical endpoints correlated with postoperative clinical outcomes. Results: Thirty-six patients were reviewed (15 females and 21 males) with a mean age of 54 years (7-81). Seventeen cases were treated for malignancy. The size of the bony defect ranged from 3 to 15 cm (mean = 9 cm). The cutaneous paddle, a surrogate for soft tissue defect, ranged from 10 to 125 ㎠ (mean = 52 ㎠). A gastrostomy tube was present in patients preoperatively (n = 8), and postoperatively (n = 14). Seventeen patients had neoadjuvant exposure to radiation. Postoperative VFSS showed penetration in 13 cases (36%) and aspiration in seven (19%). Overall, 29 patients (80.6%) achieved unrestricted diet, and this was statistically correlated with age (p = 0.037), radiation therapy (p = 0.002), and preoperative gastrostomy tube (p = 0.03). The presence of penetration or aspiration on VFSS was a strong predictor for long-term unrestricted oral diet (p < 0.001). Conclusion: Early postoperative VFSS is an excellent predictor for long-term swallowing outcomes in patients undergoing mandibular reconstruction with osteocutaneous fibula free flaps.

• Wind and Structures
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• 제14권6호
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• pp.537-557
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• 2011

While there are a number of guidelines used throughout the world in the assessment of acceptability of tall building accelerations, none are based on systematically conducted surveys of occupant reaction to wind-induced motion. In this study, occupant response data were gathered by both a self-reporting mechanism and by interviewer-conducted surveys in control tower structures over a period of four years. These two approaches were designed in conjunction with experimental psychologists to ensure unbiased reporting. The data allowed analysis of perception thresholds and tolerability at different building frequencies and in different wind climates. The long-term nature of the studies also allowed an investigation of the causes and effects of adaptation to building motion. As the surveys were designed to allow multiple use during single storms, the effects of exposure duration were investigated. A final exit survey was conducted at the primary survey location to investigate views of the acceptability of wind-induced motion and the factors underlying these views. The findings of the field studies indicate that none of the currently used acceleration guidelines address all of the factors that contribute to occupant dissatisfaction. An alternative framework for assessing acceleration acceptability is proposed.

• Structural Monitoring and Maintenance
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• 제2권1호
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• pp.35-48
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• 2015

The main objective of this study is to evaluate the long-term performance of various concrete composites in natural marine environment prevailing in the Gulf region. Durability assessment studies of such nature are usually carried out under aggressive environments that constitute seawater, chloride and sulfate laden soils and wind, and groundwater conditions. These studies are very vital for sustainable development of marine and off shore reinforced concrete structures of industrial design such as petroleum installations. First round of testing and evaluation, which is presented in this paper, were performed by standard tests under laboratory conditions. Laboratory results presented in this paper will be corroborated with test outcome of ongoing three years field exposure conditions. The field study will include different parameters of investigation for high performance concrete including corrosion inhibitors, type of reinforcement, natural and industrial pozzolanic additives, water to cement ratio, water type, cover thickness, curing conditions, and concrete coatings. Like the laboratory specimens, samples in the field will be monitored for corrosion induced deterioration signs and for any signs of failureover initial period ofthree years. In this paper, laboratory results pertaining to microsilica (SF), ground granulated blast furnace slag (GGBS), epoxy coated rebars and calcium nitrite corrosion inhibitor are very conclusive. Results affirmed that the supplementary cementing materials such as GGBS and SF significantly impacted and enhanced concrete resistivity to chloride ions penetration and hence decrease the corrosion activities on steel bars protected by such concretes. As for epoxy coated rebars applications under high chloride laden conditions, results showed great concern to integrity of the epoxy coating layer on the bar and its stability. On the other hand corrosion inhibiting admixtures such as calcium nitrite proved to be more effective when used in combination with the pozzolanic additives such as GGBS and microsilica.

• 한국농공학회논문집
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• 제62권1호
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• pp.71-81
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• 2020

Enclosed pig house are creating an environment with high concentrations of gas and dust. Poor conditions in pig farms reduce pig weight and increase disease and accidents for livestock workers. In the pig house, the high concentration of harmful gas may cause asphyxiation accidents to workers and chronic respiratory disease by long-term exposure. As pig farm workers have been aging and feminized, the damage to the health of the harsh environment is getting serious, and real-time monitoring is needed to prevent the damage. However, most of the measuring devices related to humidity, harmful gas, and fine dust except temperature sensors are exposed to high concentrations of gas and dust inside pig house and are difficult to withstand for a long time. The purpose of this study is to develop an wearable based device to monitor the hazardous environment exposed to workers working in pig farms. Based on the field monitoring and previous researches, the measurement range and basic specifications of the equipment were selected, and wearable based device was designed in terms of utilization, economic efficiency, size and communication performance. Selected H₂S and NH₃ sensors showed the average error of 5.3% comparing to standard gas concentrations. The measured data can be used to manage the working environment according to the worker's location and to obtain basic data for work safety warning.

• 농촌의학ㆍ지역보건
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• 제29권2호
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• pp.265-285
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• 2004

이 연구는 농약의 노출에 의해 중추신경 증상이 발생할 수 있으며, 장기간의 농약노출로 인해 중추신경계 영향이 있을 것이라는 가설을 검정하기 위해 농약 누적노출을 추정하였으며, 농약 노출 관련 요인에 따라 신경독성증상 호소의 차이를 보았다. 연구결과는 다음과 같다. 지난 1년 동안 농약살포시간은 과수농민 69.6시간, 밭농민 41.1시간, 축산농업인 25.8시간으로 통계적으로 유의한 차이가 있었으며, 누적노출지수는 과수농민 119.5g, 밭농민 63.9g, 축산농업인 23.7g으로 통계적으로 유의한 차이가 있었다(p<0.01). 누적노출지수에 의해 분류하면, 과수농민은 고노출군, 밭농민은 중간노출군. 축산농민은 저노출군에 해당하였다. 과거 농약중독 경험률은 과수농민 40.7%, 밭농민 35.1%, 축산농민 23.8%로 통계적으로 유의한 차이가 있었으며 (p<0.001), 지난 3개월 동안 농약중독 증상 경험률은 과수농민 67.2%, 밭농민 55.3%, 축산농민 20.5% 순으로 통계 적으로 유의한 차이가 있었다(p<0.001). 신경독성 자각증상의 총점과 6개 이상 증상을 호소하는 경우는 대조군 및 축산농민에 비해 밭농민 및 과수농민에서 유의하게 증가하였다(p<0.001). 연령, 교육수준, 성, 흡연, 음주를 보정한 상태에서도 6개 이상 신경독성 증상 발생의 교차 비는 비노출군에 비해 과수농민이 3.08(95% CI 1.50-6.30)배, 누적노출지수가 75% 이상 높은 군이 2.75(958% CI 1.12-6.78) 배, 과거 농약중독 경험이 있는 경우 1.97(95% CI 1.21-3.20)배, 현재 농약중독증상을 경험한 경우 정상군에 비해 경도 중독군 3.03(95% CI 1.47-6.22)배, 중등도 중독군이 6.34(95% CI 3.03-13.25)배 높게 나타났다. 이상의 결과로 볼 때, 신경독성증상의 발생에 일관되게 농약노출과 관련된 요인이 유의하게 나타나고, 농약노출이 높은 것으로 평가된 과수농민에서 중추신경계 증상 호소가 유의하게 녹게 나타나 만성 농약노출에 의해 중추신경계 영향이 발생할 가능성이 제기된다.

• 한국구조물진단유지관리공학회 논문집
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• 제17권1호
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• pp.10-20
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• 2013

설계시의 결함, 사용 중의 손상, 극한 환경에 장기간 노출에 따른 열화로 인해, 콘크리트 구조물의 성능은 감소된다. 본 논문은 8개 구역을 가진 대도시 철도 고가교에 대한 현장조사를 수행하고 내구성 평가를 수행한 연구이다. 대상 구조물에 대하여, 현장조사를 수행하여 내구성능을 평가하였으며, 사용상의 문제점을 도출하였다. 또한 내구지수-환경지수 산정법을 이용하여 현 상태의 상부구조 및 하부구조에 대한 내구성 확보기간을 평가하였으며, 이상적인 준공상태를 가정한 조건으로 도출된 내구성 확보기간과 비교하였다. 대상 구조물은 RC T형교, PSC 거더교, RC 박스교, 라멘교 등이 포함되어 있었으며, 각 구조형식에 따른 문제점을 분석하였다. PSC 거더의 단부균열, PSC 거더의 휨균열, 외부강선보강 정착부 균열, RC 박스의 휨균열, RC T형교의 휨균열을 주된 문제점으로 평가되었으며, 이를 패턴화하여 원인을 제시하였다. 본 연구는 각 구간의 열화에 따른 보수시기의 계획에 효과적인 자료로 사용되어질 수 있다.

• 벤처창업연구
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• 제18권4호
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• pp.207-222
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• 2023

대부분의 대학은 취업률 향상을 위하여 산헙혁력선도대학(LINC) 선정 여부와 상관없이 학생들의 취·창업역량강화 프로그램을 운영하고 있다. 특히 비수도권대학의 경우 취업률 향상을 위하여 사활을 걸고 있다. 취업률에 절대적으로 영향을 미치는 대학설립유형과 대학소재지에 대한 한계를 극복하기 위하여, 취·창업역량강화를 위하여 기업가정신 함양을 위한 창업교육·지원 프로그램을 운영하고 있으며, 지역 및 기관과 연계한 PBL(Problem Based Learning) 컨셉이 반영된 캡스톤디자인과 현장실습 프로그램을 상시 운용하고 있다. 기존 연구에서는 산헙혁력선도대학(LINC)을 중심으로 효과성 검증에 관한 연구는 수행되었으나, 공시지표를 기반으로 취업률에 미치는 요인으로서 대학요인, 창업교육·지원, 산학연계교육 요인 모두를 대상으로 한 종단연구 사례는 보고되지 않았다. 본 연구는 취업률에 미치는 요인으로 대학요인, 창업교육·지원, 산학연계교육에 대하여 최근까지 공개된 2018년부터 2020년까지 대학공시지표를 기반으로 조건을 만족시키는 116개 대학을 대상으로 51개의 산학협력선도대학(LINC) 참여대학과 64개의 비참여대학 집단간 차이분석을 하였다. 또한 공시지표의 한계로 인하여, 참여 학생의 중복참여에 대한 이력 정보가 없는 점을 고려하여 취·창업역량강화 프로그램에 장기간 노출된다면 역량강화를 통한 취업률에 영향을 미칠 것이라는 노출효과(Exposure Effect)이론을 기반으로 종단적 인과관계 분석을 통하여 2017년부터 2021년까지 2차 사회맞춤형 산학협력 선도대학 육성사업(LINC+)의 효과성을 검증하였다. 연구결과 사회맞춤형 산학협력 선도대학 육성사업(LINC+)의 창업교육·지원 및 산학연계교육 프로그램은 취업률에 영향을 미치지 않는 것으로 나타났다. 종단적 인과관계 분석결과 기존 대학요인으로 수도권대학이 비수도권대학보다 여전히 취업률이 높으며, 사립대학이 국립대학보다 취업률이 높은 것을 재확인하였다. 취·창업역량강화 프로그램 중 창업강좌 이수자수, 캡스톤디자인 이수자수, 캡스톤디자인 지급액, 전담교직원수는 취업률에 연도별 부분적으로 영향을 미치며, 현장실습은 연도별로 전혀 영향을 미치지 않으며, 취·창업역량강화 프로그램의 장기간 노출이 취업률에 영향을 미치지 않음을 확인하였다. 그러므로, 대학의 취업률 향상을 위해서는 비수도권, 국·공립대의 한계를 극복해야만 함을 재확인하였다. 이를 극복하기 위한 취·창업역량강화 프로그램으로서 창업강좌 참여를 통하여 기업가정신의 강화와 PBL(Problem Based Learning) 컨셉이 강화된 캡스톤디자인 프로그램의 적극적인 도입 및 확신이 중요하며, 현장실습 프로그램이 취업률 향상에 도움이 되기 위해서는 전반적인 학사제도 및 조직의 재정비를 통한 내실 있는 프로그램 진행이 요구된다.

• Corrosion Science and Technology
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• 제18권6호
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• pp.221-227
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• 2019

During the operation, maintenance and decommissioning of nuclear power plant radioactive contaminated waste is produced. This waste is stored in an underground repository 60-100 meters below the surface. The metallic portion of this waste comprises mostly carbon and stainless steel. A long-term field exposure showed high corrosion rates, general corrosion up to 29 ㎛ a^-1 and localized corrosion even higher. High corrosion rate is possible if microbes produce corrosive products, or alter the local microenvironment to favor corrosion. The bacterial and archaeal composition of biofilm formed on the surface of carbon steel was studied using 16S rRNA gene targeting sequencing, followed by phylogenetic analyses of the microbial community. The functional potential of the microbial communities in biofilm was studied by functional gene targeting quantitative PCR. The corrosion rate was calculated from weight loss measurements and the deposits on the surfaces were analyzed with SEM/EDS and XRD. Our results demonstrate that microbial diversity on the surface of carbon steel and their functionality is vast. Our results suggest that in these nutrient poor conditions the role of methanogenic archaea in corrosive biofilm, in addition to sulphate reducing bacteria, could be greater than previously suspected.

• 한국자원식물학회지
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• 제19권6호
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• pp.665-669
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• 2006

Somatic embryos do not survive at exposure to liquid nitrogen temperatures without cryoprotective treatments. A simplified technique which simultaneously induces and cryoprotects embryogenic calli using plant vitrification solution 2 (PVS2) followed by dehydration was developed for the cryopreservation of Soap berry genetic resources. Vitrification is a way of removing the moisture in vegetation through PVS2. The PVS2 vitrification solution consisted of 30% glycerol (w/v), 15% ethylene glycol (w/v), 15% Dimethylsulfoxide (w/v) in B5 medium containing 0.4M sucrose. Two tests were done. The one was to eliminate moisture at $0^{\circ}C$ and the other at $25^{\circ}C$. In both cases the best results came out at a vitrification time of $10{\sim}20$ minutes. It was also found that the survival rate was higher at $0^{\circ}C$ than at $25^{\circ}C$. In particular, the survival rate reached more than 80%. Water-damaged embryos turned brown and stoped growth, but energetic embryos took on a milky hue and show a very vigorous growth rate. Successful cryopreservation of somatic embryos of soapberry can be used to establish in vitro genebanks for long-term conservation of Soapberry genetic resources to complement field genebanks and other in vitro methods already being used.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.147.2-148
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• 2016

Light management technology is very important for thin film solar cells, which can reduce optical reflection from the surface of thin film solar cells or enhance optical path, increasing the absorption of the incident solar light. Using proper light trapping structures in hydrogenated amorphous silicon (a-Si:H) solar cells, the thickness of absorber layers can be reduced. Instead, the internal electric field in the absorber can be strengthened, which helps to collect photon generated carriers very effectively and to reduce light-induced loss under long-term light exposure. In this work, we introduced a chemical etching technology to make honey-comb textures on glass substrates and analyzed the optical properties for the textured surface such as transmission, reflection and scattering effects. Using ray optics and finite difference time domain method (FDTD) we represented the behaviors of light waves near the etched surfaces of the glass substrates and discussed to obtain haze parameters for the different honey-comb structures. The simulation results showed that high haze values were maintained up to the long wavelength range over 700 nm, and with the proper design of the honey-comb structure, reflection or transmission of the glass substrates can be enhanced, which will be very useful for the multi-junction (tandem or triple junction) thin film a-Si:H solar cells.