• Journal of Microbiology and Biotechnology
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• 제33권1호
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• pp.106-113
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• 2023

The supply of microbiological risk-free water is essential to keep food safety and public hygiene. And removal, inactivation, and destruction of microorganisms in drinking water are key for ensuring safety in the food industry. Ultraviolet-C (UV-C) irradiation is an attractive method for efficient disinfection of water without generating toxicity and adversely affecting human health. In this study, the disinfection efficiencies of UV-C irradiation on Shigella flexneri (Gram negative) and Listeria monocytogenes (Gram positive) at various concentrations in drinking water were evaluated using a water purifier. Their morphological and physiological characteristics after UV-C irradiation were observed using fluorescence microscopy and flow cytometry combined with live/dead staining. UV-C irradiation (254 nm wavelength, irradiation dose: 40 mJ/cm²) at a water flow velocity of 3.4 L/min showed disinfection ability on both bacteria up to 10⁸ CFU/4 L. And flow cytometric analysis showed different physiological shift between S. flexneri and L. monocytogenes after UV-C irradiation, but no significant shift of morphology in both bacteria. In addition, each bacterium revealed different characteristics with time-course observation after UV-C irradiation: L. monocytogenes dramatically changed its physiological feature and seemed to reach maximum damage at 4 h and then recovered, whereas S. flexneri seemed to gradually die over time. This study revealed that UV-C irradiation of water purifiers is effective in disinfecting microbial contaminants in drinking water and provides basic information on bacterial features/responses after UV-C irradiation.

• 한국정밀공학회지
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• 제31권10호
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• pp.865-871
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• 2014

Paradigm shift to 3-D chip stacking in electronic packaging has induced a lot of integration challenges due to the reduction in wafer thickness and pitch size. This study presents a hybrid bonding technology by self-alignment effect in order to improve the flip chip bonding accuracy with ultra-thin wafer. Optimization of Cu pillar bump formation and evaluation of various factors on self-alignment effect was performed. As a result, highly-improved bonding accuracy of thin wafer with a $50{\mu}m$ of thickness was achieved without solder bridging or bump misalignment by applying reflow process after thermo-compression bonding process. Reflow process caused the inherently-misaligned micro-bump to be aligned due to the interface tension between Si die and solder bump. Control of solder bump volume with respect to the chip dimension was the critical factor for self-alignment effect. This study indicated that bump design for 3D packaging could be tuned for the improvement of micro-bonding quality.

• 소성∙가공
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• 제27권4호
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• pp.211-221
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• 2018

To estimate the recycling feasibility of high melt-indexed polycarbonate, 3.5 inch LGP, tensile, flexural and impact specimens were injection-molded and the LGP was shredded into scraps. The scraps were injection-molded again and this process was repeated for 4 times. Properties of the sample, i.e., optical properties, mechanical properties and number average molecular weight were measured at each cycle. Based on the results, as the number of reprocessing increased, transmittance decreased at low wavelength and color coordinate was changed systematically to yellow. Yellow index increased more than twofold during 4 recycling processes. On the other hand, the number average molecular weight decreased during recycling processes. Flexural and impact strength showed no tendency according to the number of recycling, but tensile strength decreased sharply after the third recycling process. Based on these properties, it was concluded that the number of recycling for high melt-indexed polycarbonate allowed in this study was one.

• 한국음향학회지
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• 제16권4호
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• pp.76-84
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• 1997

본 논문은 이동통신기기의 핵심부품중 하나인 VCO를 IC로 설계한 내용을 기술하였다. 설계한 VCO는 배리캡을 사용한 LC 동조형발진기로 구현하였다. 사용한 발진소자중 인덕터는 실리콘 IC 구현상의 난점[8]으로 인해 외부로 구성하고 나머지부분을 모두 IC화 하였다. 제작하는데 사용된 마스크 수는 15개이며 칩 사이즈는 1150um${\times}$780um이다. 제작한 VCO IC를 테스트한 결과 전원전압 5V에서 제어전압을 1V에서 3V로 변화시킬때 880MHz 영역에서 동작하였으며 주파수 천이는 425KHz/V, 주파수 편이는 1.97MHz/T, 캐리어 레벨은 -7dBm, 전류소모는 16.7mA이었다. 또한, 위상 잡음은 50KHz 오프셋에서 -80dBc/Hz 이며 중심주파수에 대한 하모닉응답은 -41dBm 이다. 향후 송수신단을 단일 칩화하기 위해서는 외부회로도 실리콘 기판위에 구현할 수 있는 실리콘 MMIC[1][8]에 대한 연구가 수행되어야 할 것이다.

• 대한전자공학회논문지SD
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• 제47권8호
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• pp.47-55
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• 2010

본 논문에서는 고해상도 저전력 SAR 타입 ADC(아날로그 디지털 변환기)의 면적을 획기적으로 줄이기 위해서 역 다중화기 (Demultiplexer)와 카운터 (Counter)를 이용하는 타이밍 레지스터 (Timing register) 구조를 제안하였다. 전통적으로 사용되는 쉬프트 레지스터에 기반을 둔 타이밍 레지스터 구조는 해상도가 증가될수록 면적이 급격하게 증가하고, 또한 잡음의 원인이 되는 디지털 소비 전력도 증가되는 반면, 제안하는 구조는 해상도 증가에 따른 에러 보정 회로의 면적과 소비 전력 증가를 줄일 수 있다. 0.18 um CMOS 공정을 이용하여 제작하였으며, 제안한 타이밍 레지스터 구조를 이용하여, 기존 구조 대비 5.4배의 면적 감소와 디지털 전력 최소화의 효과를 얻을 수 있었다. 설계한 12 비트 SAR ADC는 11 비트의 유효 비트 (ENOB), 2 mW (기준전압 생성 블록 포함)의 소비전력과 1 MSPS의 변환 속도를 보였으며, 레이아웃 면적은 $1mm{\times}1mm$ 이었다.

• 마이크로전자및패키징학회지
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• 제24권4호
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• pp.23-29
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• 2017

본 연구에서는 선박이송용 트레슬의 표면에 부착할 수 있는 광섬유센서 패키지를 설계하고 파장다중분할방식에 기초한 센서 네트워크를 설계한 후, 모의 트레슬 유닛을 이용한 실험을 통하여 트레슬의 구조적 건전 모니터링을 위한 스마트 트레슬의 가능성을 확인하였다. 광섬유 브래그 격자 센서는 알루미늄 관으로 만들어진 원통형으로 패키징 되었다. 또한, 패키징 된 광섬유 센서를 폴리머 튜브에 삽입 한 후, 튜브 내부에 에폭시를 충전하여 센서가 해수에 대한 부식저항과 내구성을 갖도록 하였다. 패키지 된 광섬유 센서는 0.2 MPa 하의 수압테스트를 통하여 해수에서의 사용에 대한 신뢰성도 검증되었다. 트레슬의 변형에 관한 유한 요소 해석에 의해 얻어진 트레슬 부재의 변위가 큰 곳을 중심으로 트레슬에 부착할 브래그 격자의 수와 위치를 결정하였다. 최대 하중이 가해지는 트레슬 부재의 변형은 ${\sim}1000{\mu}{\varepsilon}$의 변형율로 분석되었으며, 그 때 트레슬에 걸리는 최대 하중으로 인한 센서의 브래그 파장 변화는 ~1,200 pm으로 계산되었다. 유한 요소 해석에서 얻은 결과에 따라 센서의 브래그 파장 간격을 3~5 nm로 결정하여 트레슬에 하중이 가해 졌을 때 센서 사이의 브래그 격자 파장값이 겹치지 않도록 설계하였다. 5개의 광섬유센서 패키지로 구성된 센서 모듈 5개를 연결하면 브래그 격자 센서 50개가 네트워크 될 수 있으므로, 브래그 격자 파장 검출기의 광원 중심 파장이 1550 nm에서 150 nm 광학 창 내에서 모두 검출될 수 있도록 하였다. 모의 트레슬 유닛에 부착 된 5개의 광섬유 센서 패키지의 브래그 파장 이동은 광섬유 루프미러를 사용하는 브래그 격자 파장검출기에 의해 잘 검출되었으며, 그 때 검출된 브래그 격자 센서의 값은 최대 변형률이 약 $235.650{\mu}{\varepsilon}$로 측정되었다. 센서 패키징과 네트워킹의 모델링 결과는 실험 결과와 서로 잘 일치하였다.

• Child Health Nursing Research
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• 제5권3호
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• pp.292-304
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• 1999

The lengthened average span of human life by virtue of recent developments in medicine has caused the Population of elders to increase. The development of modern industrial society has transformed family structure from the large family system to that of a nuclear family. Due to the shift in family structure, the problem of support for the aged has surfaced as a nursing problem as well as a social problem. With regard to this problem, this study aims to investigate the adolescent's understanding of elders and aging. By identifying their understanding and classifying their attitude patterns, this study will help the nursing assessment of the support of elders in the family. This study employed Q-methodology and the research was conducted from December 1998 to May 1999. One method of the research included deep interviews with elders, those who are in their 50's. 40's or 30's. and the adolescent. 183 Q-Populations taken from literary works such as poems or novels were also formed as another method. Finally. 36 Q-cards were made after consultation with Professors of the nursing department. The subjects of the P- sample were 30 high sohoolboys/girls - who were in first, second, and third years. The result showed that 3 factors provided an explanation for 59.14% of the whole variables: the first factor, 41.37%; the second factor. 11.49%, and the third factor. 6.28%. These three factors were analyzed and categorized as three types. Twenty subjects out of the 30 were included in Type 1: Respecting Elders. The statements which showed the most positive consent were as follows: 'The declining age is a perfect time to prosper completing a worthy life' ; 'Getting old. one needs financial stability' and 'Elders wish the best for their children' The statements showing the most negative response were as follows: 'It is better to die than to live as an older person' ; 'Elders are insignificant' ; and 'Getting old is the worst unhappiness that tortures human.' Four subjects were included in Type 2. Resenting Elders. The statements which showed the most positive consent were as follows: 'Aging is a process of dying that nobody can escape from'. 'Elders should be concerned about his health and try to maintain their health' ; and 'When you set older. you regret about the life in the Past.' The statements showing the most negative response were as follows: 'When You get older. You should stand aloof greed and worldly things' 'When You got older, You become generous and gentle' ; and 'When You set he gets old. You change to become a comfortable and warm person.' Six out of 30 subject were included in Type 3 Caring Elders. The statements which showed the most positive consent were as follows: 'Elders should be concerned about his health and try to maintain their health' ; 'Elders wish the best for their children' ; and 'Elders deserve to be treated with filial respects.' The statements showing the most negative response were as follows 'Elders are insignificant' ; 'Elders have freedom and plenty of free time.' and 'Elders are alienated form and drove out of the society.' The above-mentioned results show that most adolescents in Korea recognize aging as the time of fruition and development: it is a time of benefiting and giving back to society. Aging can also be seen as a time of generosity and magnanimity and the time of respect and favorable treatment from society. despite the change of modern society and the ostensible transformation of a family system. Their recognition seems deeply rooted in the traditional confucian values and the dual family system which is Peculiar especially to the Korea - one which maintains both the superficial form of nuclear family and the substantial mode of the enlarged family system. In sum, many Korean adolescents attribute the meaning of the elderly and aging to the type of the respect with the elderly and the type of the elderly's caretaking.