• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.103-108
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• 2008

Topics discussed in this paper are engineering design of artificial reefs, design considerations of compressive strength and pH, materials of silica fume concrete and volcanic stones for reef construction, and field monitoring of artificial reefs. Six artificial reefs were deployed offshore at Biyangdo in July 2006, and succession patterns on the reefs were investigated bimonthly from July 2006 to October 2007. The spore-bag method, which has been widely used in Korea for the attachment of seaweed on artificial reefs, was applied to the developed reefs using the kelp Ecklonia cava, which is the dominant species in Jeju, and recruitment and growth patterns were observed.

• The Journal of the Korean dental association
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• v.9 no.12
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• pp.841-845
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• 1971

Author has made the studies on the pH of pus in the 53 suppurative disesed patients who had admitted to department of ora surgery, Infirmary of Schoo of Dentistry, Seoul National University. The results were obtained as follows; 1. The average pH of pus in the patients with suppurative oral diseases was 6.46 and the pH of pus was ranging 5.0 to 7.2. 2. The pH value of pus was not significant between the males(pH: 6.58) and females (pH: 6.40). 3. The pH vaule of pus in patients treated by antibiotics trend to slightly alkaline than that of untreated patients. 4.The pH vaule of pus in the pericoronitis, periodontal abscess and other localized oral infections were slightly alkaline than buccal abscess and osteomyelitis, and acute suppurative diseases of jaws was more acid than chronic diseases. In general, it was seemed the early stages of inflammation was alkaline, and the later stages was acid.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.42-49
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• 2003

In this paper, we provide the results of polishing temperature distribution by way of infrared ray measurement system as well as polishing resistance, which can be interpreted as tribological aspects of CMP, using force measurement system. The results include the trend of polishing temperature, its distribution profile and temperature change during polishing. The results indicate that temperature affects greatly to the removal rate. Polishing temperature increases gradually and reaches steady state temperature and the period of temperature change occurs first tens of seconds. Furthermore, the friction force also varies as the same pattern with polishing temperature from high friction to low. These results suggest that the first period of the whole polishing time greatly affects the nonuniformity of removal rate.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.195.2-195.2
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• 2016

대기압 플라즈마는 공기중에서 방전이 가능하고, 이때 생성되는 활성산소종(ROS)과 활성질소종(RNS)을 적절히 이용하면 살균은 물론 제독이 가능하다. 특히 신경작용제나 수포작용제 등의 화학물질은 박테리아 포자, 세균, 바이러스 등의 생물작용제에 비해 더 많은 에너지와 시간이 요구된다. 현재 군이나 의료 시설에서는 과산화수소를 이용한 제독이나 염소계 표백제 성분으로 구성된 수용성 제독제를 이용하지만, 플라즈마의 경우는 단순히 기체를 방전하여 제독에 이용할 수 있으므로 보다 제독 시스템을 간단하게 구성할 수 있다. 하지만 대기압 방전시 방전전압을 낮추기 위해 헬륨과 알곤등의 기체를 공급하여 사용할 경우 부가적인 시스템의 규모가 커져 활용에 제한이 따른다. 따라서 본 연구에서는 대기중에 존재하는 질소, 산소 등을 이온화시키기 위해 10-25kHz의 주파수에서 4.5kV의 8us 펄스전원을 인가하여 공기 플라즈마를 얻고, 열에 의한 분해효과를 제거하기 위해 플라즈마의 기체온도를 20도로 유지시켰다. 플라즈마의 특성은 방출광 분석법을 이용하여 떨림온도를 계산하였고, 질소와 오존의 농도를 동시에 관찰하였다. 분해된 화학작용제는 기체분석기(Gas Chromatography)를 통해 표준 오염농도대비 잔류한 양을 측정함으로써 제독효율을 계산하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.955-961
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• 2009

Present, a portable battery have problem that the volume increases according to capacity Increase. Direct Methanol Fuel Cell is alternative by solution plan of this problem. In this paper, the characteristics of DMFC are analyzed by change in concentration and discharge of fuel in natural convection and room temperature condition. According to the analysis result, polarization by delay of diffusion velocity of hydrogen ion appeared in methanol of low concentration. And if have a lot of supplies of methanol, generation power declines by electric cell cooling effect.

• Journal of Oral Medicine and Pain
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• v.17 no.2
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• pp.87-97
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• 1992

The purpose of this study is to investigate the age-and sex-related changes in the pH of resting saliva, viscosity, microorganisms and immunoglobulin A of stimulated whole saliva, and to investigate their correlations. The 120 healthy subjects were included in this study and the author used cone-and plate digital viscometer for viscosity, MSB agar for Streptococcus mutans, SL Rogosa agar for lactobacilli, and single radial immunodiffusion technique for immunoglobulinA. The obtained results were as follows : 1. There was no significant difference in pH, viscosity, Streptococcus mutans lactobacilli and immunoglobulin A of the saliva between males and females. 2. The viscosity values of stimulated whole saliva showed the increasing pattern with aging. 3. DMFS (or dmfs) rate was not correlated with pH, viscosity, Streptococcus mutans, lactobacilli and immunoglobulin A of the saliva. 4. There was a significant difference in the concentration of immunoglobulin A between the group under 10 and groups above 10. 5. The viscosity values of stimulated whole saliva showed the increasing pattern with decreasing of the number of Streptococcus mutans.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.101-106
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• 1992

pH-ISFETs, the semiconductor pH sensors, were combined with immobilized enzyme membranes to prepare FET type urea and glucose sensors and its operational characteristics were investigated. Photolithography techniques were applied to immobilize enzymes on the $H^{+}$ sensing membrane of the pH-ISFET with photo-sensitive polymers, PVA-SbQ. Fabricated urea and glucose sensors could determine $0.5{\sim}50{\;}mg/dl$ urea concentrations and $10{\sim}1000{\;}mg/dl$ glucose concentrations, respectively.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.496-503
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• 1992

An ISFET urea sensor was fabricated by immobilizing the urease using photosensitive polymer, poly(vinyl alcohol)-SbQ on the H$^+$ sensing $Si_3$$N_4$ thin film of pH-ISFET. The sensor could determine the urea concentration in the range of 1∼50 mg/dl with fast response and good repeatability. For its application to clinical analysis, the interferences of the various materials which cause inhibition in urease catalytic reactions in blood was investigated. The results of the urea measurements in blood plasma using the ISFET urea sensor were compared with these of conventional spectrophotometric method.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.41-48
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• 1993

An ISFET urea sensor was fabricated by immobilizing the urease using polyurethane on the $H^{+}$ sensing $Si_{3}N_{4}$ thin film of pH-ISFET. The sensor could determine the urea concentration $1{\sim}50$ mg/dl with fast response of $3{\sim}5$ min. and good repeatability. For its application to clinical analysis, the results of the urea measurements in blood plasma using ISFET urea sensor were compared with these of conventional Urease-Indophenol method.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.201-203
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• 2007

본 논문에서는, 연료전지 시스템의 기계적 주변장치 (MBOP)와 전기적 주변장치 (EBOP)의 최적 설계를 위해서 PEMFC 스택을 전기화학반응을 기초로 모델링한다. 모델링을 위해 기본적인 PEMFC의 구조와 동작 원리를 설명한다. 연료전지의 이론적 최고 전압인 평형전위를 깁스 자유에너지와 네른스트 방정식으로 유도한다. 전류밀도에 따른 전압 손실인 활성화, 저항, 농도 분극현상을 표현하기 위해서 수식을 유도한다. 수소가 이온화되지 못하고 산소극으로 넘어가서 발생되는 연료손실 및 내부전류와 지속적인 정역반응인 교환전류도 모델링된다. 평형전압에서 각 분극을 뺀 실제 운전 전압을 시뮬레이션하고, 유량과 압력에 따른 출력 특성을 시뮬레이션 한다. 부하변동 시 출력특성을 시뮬레이터와 실험결과로 비교한다.