Polyphosphate가 Porphyromonas endodontalis의 성장에 미치는 영향에 관한 연구

최성백,최호영,민병순,박상진,이진용,최기운 大韓齒科保存學會 1998 Restorative Dentistry & Endodontics Vol.23 No.1

Polyphosphate has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of polyphosphate on the growth of Porphyromonas endodontalis, a gram negative endodontopathic bacterium. Porphyromonas endodontalis ATCC 35406 was grown in the presence of polyphosphates with different chain lengths. Inhibitory effect of each polyphosphate which was added at the beginnig or during the culture, was determined by measuring the optical density of the bacterial cell at 540nm and by viable cell count. The results from this study were as follows : 1. Polyphosphates were shown the growth inhibition of the Porphyromonas endodontalis. 2. The minimal inhibitory concentration(MIC) of polyphosphate was observed to be 0.04%. 3. Polyphosphates with chain lengths of 25 and 75 demonstrated the greatest inhibitory effect on the growth of Porphyromonas endodontalis. 4. Polyphosphates are bactericidal to Porphyromonas endodontalis, demonstrating the growth inhibition of the bacterium. The overall results suggest that use of polyphosphate may affect the growth of Porphyromonas endodontalis. Further studies will be needed to confirm the effect of Polyphosphate.

리니어 모터로 이송되는 탄성체의 진동 최소화를 위한 이송속도 최적화 연구

최영휴,홍대선,최응영,최국진 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

Linear motor feed drive systems have been broadly used in machine tools or precision automatic systems. Recently, modern machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was designed optimally, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes serious vibrations in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

유아의 자연물에 대한 연상, 유사성, 생명 개념에 관한 연구

최진승,김지영 동아대학교 교육대학원 1998 동아교육논총 Vol.24 No.-

본 연구는 유아가 자연물에 대한 지식을 연상하고 생명 유무와 유사성을 판단하는 기준을 공통적인 준거로써 찾고 그 준거별 반응정도가 연령 및 성별, 자연물의 범주에 따라서 어떠한 양상을 보이면서 발달하는지 밝히는데 그 목적을 두었다. 본 연구의 대상은 부산 시내 유치원에 재원하는 3, 4, 5세 유아 90명이며 유아에게 제시된 자연물은 예비 조사와 친숙도 검사를 통해 선정하였으며, 범주에 따라서 동물, 식물, 천체, 기타 무생물 범주로 나뉘며 각 범주별로 3개씩 총 12개이다. 자료는 인터뷰식으로 진행하여 수집되었으며 유아의 반응은 모두 녹음하여 준거에 따라 수량화하였고, 통계처리는 일원변량분석, 다변량분석, t-검증, Duncan(.05)사후 검증 등을 활용하였다. 본 연구의 결과 및 논의를 통해 얻어진 결론은 다음과 같다. 첫째, 자연물의 소유, 형태, 주제에 관한 개념은 3세에 이미 발달되어 있으며, 색깔과 기능에 관한 개념은 4세와 5세 사이에 크게 발달하는 것으로 보인다. 둘째, 여아는 남아보다 자연물의 기능 및 행위에 관한 개념을 더 먼저 획득한다. 셋째, 동물 및 기타 무생물 범주에 관한 자연물의 개념은 식물 범주 및 천체 범주에 대한 개념보다 더 먼저 발달한다. 넷째, 유아의 자연물의 유사성 판단은 주제-지각-기능-개념 이행으로 변화하며 발달한다. 여섯째, 유아들이 자연물과 유사한 대상으 판단할 때 근거하는 기준은 자연물의 범주에 따라 다른데, 생물 범주는 기능적인 법칙에 근거하고 무생물 범주는 지각적인 특징에 근거하여 판단한다. 일곱째, 자연 법칙에 근거하여 자연물의 생명성을 판단할 수 있는 능력은 5세에 갖추어어지며, 자연물의 범주에 따라 생명성의 판단의 기준이 다르다. 동물 범주는 자연법칙에 근거하며 식물 범주는 사람들의 활동과 개입 유무에 근거하고, 무생물 범주는 의인적인 준거에 근거하여 판단하는 경향이 높다. The purpose of this study is that how the young childrens' association, simialrity, life concept on natural kinds changes with age, sex, and the categories of natural kinds. The subjects in this study were 90 young children who were 3, 4, and 5 years old, and sampled from 3 kindergartens in Pusna. Natural kinds were selected through the pilot test and the categories of natural kinds were divided into animal, plant, planet, and dnonbiological category. Following conclusions were derived from discussion on the results to this study: 1.Young children's association about natural kinds' having, shape, thematic knowledge don't change with age, and their association for the color, functional knowledge of natual kinds were increaed with age. 2.Female childrens' association is higer than male in the natural kinds' functional knowledge. 3.Young childrengs association about plant, planet is increasing with age. Therefore, young childrens' concept about animal, nonbiological kinds is formed nearly at 3 age olds, and young childrens' concept about plant, planet develops highly between the age of 4 and 5 years old. 4.Young children's association about natural kinds' shape is high in the all categories of natural kinds, their assocaition about natural kinds' thematic knowledge is high in nonbiological category. In addition, their association about natural kinds' function is high in animal category at most. 5.Young childrens' reponses about natural kinds' thematic simiarity are decreasing with age. On the other hand, their responses about natural kinds' perceptual, functional simiarity are increasing with age. The result suggests that young childrens' concept on natural kinds is developing thematic-perceptural-founctional-conceptual shift. 6.Young childrens' assocaition about the simiarity is based on objects' founctional character in biological category. On the other hand, their assocaition about inanimates' similarity is based on the perceptual character in nonbiological category. 7.Young childrens' ability to discriminate the animates-nonanimates is increasing at 5 years old. Therefore, young childrens' life concept is formed nearly at 5 years old. 8.Young childrens discriminate between animate and inanimate things in animal category at the based of animals' functional character and in plant category at the based of persons' activity. However they justify the objects' lives at the based of perceptual character in nonbiological category.

1~2기 본태성 고혈압 환자들에서 Imidapril 대 Enalapril의 항고혈압 효과를 평가하기 위한 무작위, 이중맹검 임상시험

최영진,손대원,김용진,이홍자,채인호,김효수,김철호,오병희,이명묵,박영배,채윤식,이영우 대한순환기학회 1999 Korean Circulation Journal Vol.29 No.11

Reliability Considerations of Hybrid Power Systems for Critical Facilities

Choi, Se Jin · Ham, Young Hwan · Kim, Myung Chin 충북대학교 컴퓨터정보통신연구소 2008 컴퓨터정보통신연구 Vol.27 No.2

본문참고

AN IN-SITU YOUNG’S MODULUS MEASUREMENT TECHNIQUE FOR NUCLEAR POWER PLANTS USING TIME-FREQUENCY ANALYSIS

YOUNG-CHUL CHOI,DOO-BYUNG YOON,JIN-HO PARK,권휴상 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.3

Elastic wave is one of the most useful tools for non-destructive tests in nuclear power plants. Since the elastic properties are indispensable for analyzing the behaviors of elastic waves, they should be predetermined within an acceptable accuracy. Nuclear power plants are exposed to harsh environmental conditions and hence the structures are degraded. It means that the Young’s modulus becomes unreliable and in-situ measurement of Young’s modulus is required from an engineering point of view. Young’s modulus is estimated from the group velocity of propagating waves. Because the flexural wave of a plate is inherently dispersive, the group velocity is not clearly evaluated in temporal signal analysis. In order to overcome such ambiguity in estimation of group velocity, Wigner-Ville distribution as the time-frequency analysis technique was proposed and utilized. To verify the proposed method, experiments for steel and acryl plates were performed with accelerometers. The results show good estimation of the Young’s modulus of two plates.

Comparison of risk and protective factors associated with smartphone addiction and Internet addiction

Choi, Sam-Wook,Kim, Dai-Jin,Choi, Jung-Seok,Ahn, Heejune,Choi, Eun-Jeung,Song, Won-Young,Kim, Seohee,Youn, Hyunchul Akadémiai Kiadó 2015 JOURNAL OF BEHAVIOURAL ADDICTIONS Vol.4 No.4

<P><B>Background and Aims</B></P><P>Smartphone addiction is a recent concern that has resulted from the dramatic increase in worldwide smartphone use. This study assessed the risk and protective factors associated with smartphone addiction in college students and compared these factors to those linked to Internet addiction.</P><P><B>Methods</B></P><P>College students (<I>N</I> = 448) in South Korea completed the Smartphone Addiction Scale, the Young’s Internet Addiction Test, the Alcohol Use Disorders Identification Test, the Beck Depression Inventory I, the State–Trait Anxiety Inventory (Trait Version), the Character Strengths Test, and the Connor–Davidson Resilience Scale. The data were analyzed using multiple linear regression analyses.</P><P><B>Results</B></P><P>The risk factors for smartphone addiction were female gender, Internet use, alcohol use, and anxiety, while the protective factors were depression and temperance. In contrast, the risk factors for Internet addiction were male gender, smartphone use, anxiety, and wisdom/knowledge, while the protective factor was courage.</P><P><B>Discussion</B></P><P>These differences may result from unique features of smartphones, such as high availability and primary use as a tool for interpersonal relationships.</P><P><B>Conclusions</B></P><P>Our findings will aid clinicians in distinguishing between predictive factors for smartphone and Internet addiction and can consequently be utilized in the prevention and treatment of smartphone addiction.</P>

AN IN-SITU YOUNG'S MODULUS MEASUREMENT TECHNIQUE FOR NUCLEAR POWER PLANTS USING TIME-FREQUENCY ANALYSIS

Choi, Young-Chul,Yoon, Doo-Byung,Park, Jin-Ho,Kwon, Hyun-Sang Korean Nuclear Society 2009 Nuclear Engineering and Technology Vol.41 No.3

Elastic wave is one of the most useful tools for non-destructive tests in nuclear power plants. Since the elastic properties are indispensable for analyzing the behaviors of elastic waves, they should be predetermined within an acceptable accuracy. Nuclear power plants are exposed to harsh environmental conditions and hence the structures are degraded. It means that the Young's modulus becomes unreliable and in-situ measurement of Young's modulus is required from an engineering point of view. Young's modulus is estimated from the group velocity of propagating waves. Because the flexural wave of a plate is inherently dispersive, the group velocity is not clearly evaluated in temporal signal analysis. In order to overcome such ambiguity in estimation of group velocity, Wigner-Ville distribution as the time-frequency analysis technique was proposed and utilized. To verify the proposed method, experiments for steel and acryl plates were performed with accelerometers. The results show good estimation of the Young's modulus of two plates.

영구형 항서맥 심박조율기 환자의 장기추적관찰

최현석,이무용,최영진,최성준,김효수,손대원,오병희,이명묵,박영배,최윤식,이영우,이명용 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.5

What makes hybrid insourcing successful: A new public–private partnership model for social welfare services

Yang Jae‐jin,Kim Hey Sung,Choi Seong Eun,Ryu Lanhee,Choi Young Jun 한국사회복지학회 2020 Asian Social Work and Policy Review Vol.14 No.1

Outsourcing has been a key policy tool for delivering a range of social services, and regarded as more effective than insourcing or direct government provision. At the same time, it has also caused many delivery issues such as principal‐agent problems, a lack of policy coordination, and poor‐quality welfare services. While the pendulum continues to swing between insourcing and outsourcing, we aim to propose a new public–private partnership model called the “hybrid insourcing model” and examine which factors influence the performance of the model. In South Korea, around 2010, the local government in Namyangju City was the first to implement the “Hope Care Center model,” a kind of hybrid insourcing model, which has been praised for its innovation and widely emulated by central and local governments. Our analysis utilizes data collected between December 2017 and January 2018 from public sector employees and civilian staff in Namyangju and a comparable city, A. From this, we draw a number of implications, both for theory and for policy. We argue that, for public–private partnerships, active cooperation and equality are the biggest factors in contributing to positive performance. These work alongside leaders with a clear vision and with employees' positive attitude