Opening and blocking the inner-pores of halloysite

Joo, Yongho,Sim, Jae Hyun,Jeon, Yangjun,Lee, Sang Uck,Sohn, Daewon The Royal Society of Chemistry 2013 Chemical communications Vol.49 No.40

<P>Aggregation and dispersion behaviours of halloysite nanotubes (HNTs) were influenced by pH. The meso- and micro-porosity of halloysite were determined by N<SUB>2</SUB> gas physisorption. The blocking and opening of halloysite nanotube pores with acid, neutral, and base treatment were detected in a micro- and mesoporous matrix of tunable porosity. The inner pores of HNTs were opened with base treatment, but were closed with acid or neutral treatment.</P> <P>Graphic Abstract</P><P>Aggregation and dispersion behaviours of halloysite nanotubes (HNTs) were influenced by pH. The inner pores of HNTs were opened with base treatment, but were closed with acid or neutral treatment. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc40465j'> </P>

모형 연소기의 연소 불안정성 연구용 섭동 장치의 기능 검증 및 분석

민용호(Yongho Min),손채훈(Chae Hoon Sohn) 한국추진공학회 2012 한국추진공학회 학술대회논문집 Vol.2012 No.5

본 연구에서는 연소실 내의 압력섭동에 의해 발생되는 연소 불안정 상황을 모사하기 위한 시험 도구로서 섭동장치를 제작하였고, 이에 대한 성능 실험을 수행하였다. 공급되는 산화제의 유동의 흐름을 조절하여 교란을 발생시켜 인위적인 섭동을 유발할 수 있는 디스크 형태의 섭동 발생 장치를 제작하고 특성을 파악하였다. 디스크의 회전에 따라 주파수를 조정하여 모델 연소실내의 공진 주파수와의 동조가 가능하였다. 압력센서를 이용하여 섭동의 크기를 파악할 수 있었다. 따라서 설계된 섭동 장치는 연소 불안정 연구에 활용될 수 있을 것으로 판단된다. A mechanical pulsator is manufactured for study of combustion instabilities in a model chamber with impinging-jet injectors. Artificial disturbance is generated by the device and thereby, artificial instability can be examined experimentally. A sample F(fuel)-O(dxidizer)-O-F impinging-jet injector is adopted for the test. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions. Pressure fluctuation data, which is obtained from the dynamic pressure transducers installed in combustion chamber, is analyzed.

蒸發法에 의한 Ag 超微粒子 製造에 관한 硏究

李龍鎬,孫秉淸,慶在浩 弘益大學校 1976 弘大論叢 Vol.8 No.-

Fine particles of Ag were prepared by means of evaporation in Nitrogen gas at low pressures. Smoke particles collected at different parts were studied through electron microscopy. The particle size varied with the position of collecting particles. They were small and uniform between the evaporating point and the short distance, while they were large and multiform at the far longer distance.

스월 동축형 분사기 화염 특성에 관한 실험적 연구

민용호(Yongho Min),김승환(Seunghwan Kim),손채훈(Chae Hoon Sohn),홍문근(Moongeun Hong),이수용(Sooyong Lee) 한국추진공학회 2012 한국추진공학회 학술대회논문집 Vol.2012 No.11

본 연구에서는 고성능 다단로켓 엔진에 사용되는 스월 동축형 분사기의 화염 특성을 실험적 연구를 통해 분석하였다. 이를 위해 실제 추진제 조합은 기체-액체이지만, 선행 연구의 scaling method를 통해 기체-기체로 모사하였다. 연료의 경우 액체 케로신이 아닌 헥산 증기를 이용하였으며, 이때 수력학적 상사성 인자인 MFR(momentum flux ratio)을 유지시켰다. 최종적으로 혼합 및 연소 특성에 영향을 미치는 주요인자인 MFR비에 따른 화염 형상을 비교 분석 하였다. MFR비가 감소함에 따라 Yellow 화염은 감소하는 반면 Blue화염은 더욱 선명하고 강한 스월을 형성하였다. 이는 MFR비가 감소할수록 연료의 유량이 증가하는데 이로 인해 접선 방향의 속도가 증가하고, 축방향의 속도는 감소하여 혼합 특성이 향상됨을 알 수 있었다. The flame characteristics of a swirl coaxial injector are studied experimentally. Liquid rocket should have high confidence in its combustion performance and combustion stability. Especially, the injector, of which function is to inject and mix propellants, plays an important role in getting the confidence. Propellant phases of liquid-liquid are simulated as gas-gas combination. This experimental observation showed flame characteristics of a swirl coaxial injector by using the similarity method.

Aggregation and Stabilization of Carboxylic Acid Functionalized Halloysite Nanotubes (HNT-COOH)

Joo, Yongho,Jeon, Yangjun,Lee, Sang Uck,Sim, Jae Hyun,Ryu, Jungju,Lee, Sungyoung,Lee, Hoik,Sohn, Daewon American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.34

<P>We modified the functional groups of holloysite nanotubes (HNT) from hydroxyl groups (HNT-OH) to carboxylic acids (HNT-COOH). Aggregation and dispersion properties of HNT-COOH under dry conditions were probed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover, the degree of aggregation and dispersion of HNT-COOH in acidic, basic, and neutral solutions were measured by multiple angle polarized dynamic light scattering (MA-DLS). HNT-COOH formed aggregates in neutral solution; however, the material was dispersed in basic and acidic solutions. This occurrence is due to hydrogen bonds (HB) between the carboxyl groups of HNT-COOH in neutral solution, which decrease in acidic and basic solution due to charge dispersion.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-34/jp3038945/production/images/medium/jp-2012-038945_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3038945'>ACS Electronic Supporting Info</A></P>

Design of Alignment Mark Stamper Module for LED Post-Processing

Hwang, Donghyun,Sohn, Young W.,Seol, Tae-ho,Jeon, YongHo,Lee, Moon G. The Korean Society of Manufacturing Technology Eng 2015 한국생산제조학회지 Vol.24 No.2

Light emitting devices (LEDs) are widely used in the liquid crystal display (LCD) industry, especially for LCD back light units. Therefore, much research has been performed to minimize manufacturing costs. However, the current process does not process LED chips from broken substrates even though the substrate is expensive sapphire wafer. This is because the broken substrates lose their alignment marks. After pre-processing, LED dies are glued onto blue tape to continue post-processing. If auxiliary alignment marks are stamped on the blue tape, post-processing can be performed using some of the LED dies from broken substrates. In this paper, a novel stamper module that can stamp the alignment mark on the blue tape is proposed, designed, and fabricated. In testing, the stamper was reliable even after a few hundred stamps. The module can position the stamp and apply the pattern effectively. By using this module, the LED industry can reduce manufacturing costs.

The development of a quality prediction system for aluminum laser welding to measure plasma intensity using photodiodes

Jiyoung Yu,Yongho Sohn,박영환,Jae-SeobKwak 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10

Lightweight metals have been used to manufacture the body panels of cars to reduce the weight of car bodies. Typically, aluminum sheets are welded together, with a focus on weld quality assurance. A weld quality prediction system for the laser welding of aluminum was developed in this research to maximize welding production. The behavior of the plasma was also analyzed, dependent on various welding conditions. The light intensity of the plasma was altered with heat input and wire feed rate conditions, and the strength of the weld and sensor signals correlated closely for this heat input condition. Using these characteristics, a new algorithm and program were developed to evaluate the weld quality. The design involves a combinatory algorithm using a neural network model for the prediction of tensile strength from measured signals and a fuzzy multi-feature pattern recognition algorithm for the weld quality classification to improve predictability of the system.

c-Fos Expressions in the Nucleus of the Solitary Tract Following Taste Stimulation with Salts in Rats

( Un Jeng Kim ),( Yongho Kwak ),( Jeongsoo Han ),( Jin Hun Sohn ),( Shigeki Watanuki ),( Bae Hwan Lee ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

This study aims to explore and identify semantics of emotions evoked in the cognitive process of human beings when they are stimulated by different physical signals presented on information displays. To do this, we compared emotion maps driven from two independent experimental setups. Kansei engineering approaches using semantic differential method were adopted to draw the emotion maps. In each experimental setup, different set of subjects were asked to evaluate levels of semantic associations between physical stimuli and delivering information. The information to deliver was defined using sets of adjectives that are useful to describe various states of process in or out of control. Distinctive earcons and hapticons with different design parameters were given as the physical stimuli in each experiment. Factor analysis was applied to determine the dimensions, locations of adjectives and stimuli on each emotion map. The results showed that people`s emotions corresponding to given physical stimuli can be abstracted into 2 dimensions when they are expressed using the set of adjectives in the experiments.

Design of Alignment Mark Stamper Module for LED Post-Processing

Donghyun Hwang,Young W. Sohn,Tae-ho Seol,YongHo Jeon,Moon G. Lee 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.2

실시간 뎅기열 관리를 위한 관제시스템 개발

안창선 ( Changsun Ahn ),박용호 ( Yongho Park ),문정대 ( Jungdae Moon ),박종찬 ( Jongchan Park ),서영곤 ( Youngkon Seo ),손유락 ( Allen Sohn ),최윤종 ( Yoonjong Choi ),하양화 ( Yanghwa Ha ),정봉수 ( Bongsu Jung ),김영주 ( Youngjoo 한국정보처리학회 2023 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.12 No.2

뎅기열 발병은 전 세계 인구의 약 1/3이 거주하고 있는 열대, 아열대 기후에 집중되며, 우리나라도 아열대 기후로 바꾸고 있어 뎅기열 발병에 취약해지고 있다. 뎅기열은 감염병 관리 차원에서 진단 이력 관리가 중요하다. 감염병 이력에 따라서 지역별, 연령별, 남녀비율 등에 따라서 개개인의 치료 방법과 전략을 수립할 수 있는 체계가 필요하다. 본 논문에서는 뎅기열 관제시스템을 제안하며, 이러한 시스템은 뎅기열의 발병에 대한 체외진단기기를 이용한 실시간 집계방식으로 발병률과 사망률을 감소시킬 수 있는 전략을 수립하는 데 유용하게 활용될 수 있다. 뎅기열 관리를 위한 관제시스템 구성으로 형광면역진단 키트를 이용한 뎅기열 체외진단기기와 실시간 뎅기열 관제시스템으로 구성되어 있다. 본 논문으로 개발된 뎅기열 관제시스템은 향후 정부의 감염병 통합정보와 결합되어 다양한 감염병 관리 및 정책 활용을 위해서 활용될 수 있을 것이다. Dengue virus transmission is a viral infection disease between humans and Aedes mosquitoes. Dengue is ubiquitous throughout the tropics and subtropical zones, where 1/3 of the global population live. The weather in Korea is also changing to subtropical weather, resulting in increased vulnerable Korean population to dengue virus transmission. It is important to control and prevent the dengue risk with track-recording & monitoring system. It is also required to have the control system to treat and monitor dengue patients with various cases such as regions, ages, genders according to the track-record of the disease. In this paper, we developed a Dengue Control & Prevention System, which can monitor and control dengue outbreaks in real-time with in-vitro diagnostic devices. Dengue Control & Prevention System is composed of in-vitro diagnostic device, which is a fluorescent immunoassay, and real-time monitoring system. In the future, we expect that our Dengue Control & Prevention System can be upgraded to have various disease information from Korea Disease Control and Prevention Agency for government policies and diseases control in Korea.