• Title/Summary/Keyword: Unstable surface

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Controlling the Location of Thermally Stable Au Nanoparticles with Tailored Surface Property within Block Copolymer Templates (열적으로 안정한 금나노입자를 이용한 블록공중합체 내에서의 입자위치 조절)

  • Kim, Se-Yong;Yoo, Mi-Sang;Jung, Se-Ra;Paek, Kwan-Yeul;Kim, Bum-Joon J.;Bang, Joona
    • Polymer(Korea)
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    • v.35 no.3
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    • pp.238-243
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    • 2011
  • Organic/inorganic hybrid materials have a lot of interest in various areas due to their fascinating properties. To control the location and dispersion of inorganic nanoparticles within polymer matrix. thiol-terminated polymeric ligands have been widely used to tune the surface property of nanoparticles. However, the specific binding between the thiol functional group and metal is unstable with increasing temperature. To archive the thermally-stable Au nanoparticles, we previously synthesized various UV-crosslinkable polymeric ligands, which have different compositions of polar, UV-crosslinkable azide unit comparing to non-polar 스티렌 units. After crosslinking the Au nanoparticles, it was found that the nanoparticles had superb stability at high temperature (above $180^{\circ}C$). In this work, we used thermally-stable Au nanoparticles to control the location within the polymer matrix. By changing the amount of polar azide units in the polymeric ligands, we could precisely control the location of nanoparticles from one domain to the interface of block copolymer templates.

Effect of Modified Flank Exercise on Abdominal Muscle Thickness Using Sling Suspension System (슬링현수장치를 이용한 변형 플랭크 운동이 복부 근육 두께에 미치는 영향)

  • Lee, Keoncheol;Bae, Wonsik;Kim, Hyeonsu;Kang, Raekyung;Jang, Haejin
    • Journal of The Korean Society of Integrative Medicine
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    • v.6 no.4
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    • pp.39-45
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    • 2018
  • Purpose : The purpose of this study is to investigate the effect of core motion pattern on abdominal muscle thickness on unstable support surface using sling suspension system and to provide an effective exercise program for therapeutic rehabilitation in clinical practice. Methods : In this study, we used the flank exercise using a sling. It was intended for 21 healthy men and 9 healthy women. Before and after the exercise of the subjects, abdominal muscles (EO, IO, TrA the thickness of the muscle) was determined using a diagnostic ultrasonic apparatus. The period of exercise was 3 times a week for 6 weeks. The exercise for each group started with 3 sets per week and 1 set per week was added. A description of the method and attitude of each exercise is as follows. First, the push-up flank 's exercise position is to put both feet on the sling and hold the floor with both hands. Second, the side flank's exercise postures take the side flanks, while the two legs hang on the sling and one arm supports the body with an articulated bend (about $90^{\circ}$). Third, the elbow flank's exercise position is to put the two legs on the sling, and take a flank posture with the arms bent and joint bending (about $90^{\circ}$). Results : There was a significant difference in the thickness of the muscle in the three flank movements after the exercise (p<.05). The most significant difference was in the change of the muscle thickness in the abdominal muscle, the outer muscle, and the stomach in the elbow flank exercise after exercise. There was a significant difference between the mean thickness of the abdominal muscles according to the flank type after exercise (p<.05). Conclusion : In flank exercise for core stabilization using sling, it is considered effective to strengthen the abdominal muscles by considering the support surface, difficulty level, change of movement pattern.

Proper Monitoring Methods for Safety Management of Tailings Dam (광물찌꺼기적치장의 안전관리를 위한 적정 모니터링 방안 연구)

  • Jung, Myung Chae;Kim, Jeong Wook;Hwang, In-ho;Yang, In Jae;Park, Jay Hyun;Park, Ju Hyun;Kim, Tae Youp
    • Journal of the Korean Society of Mineral and Energy Resources Engineers
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    • v.55 no.6
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    • pp.576-587
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    • 2018
  • This study has focused on analysis factors affecting safety monitoring system at tailings sites, and the evaluation equipment to monitor the factors. Twenty sites at eighteen mines with unsafe conditions were selected to examine the equipment. There were three main factors influenced safety in the sites including surface erosion, piping, and slope instability. In detail, the surface erosion was divided into three sub-factors (planting, soil-topping layer, and tailings), piping into three sub-factors (liner, rain protection facility and leachate), and slop instability was also divided into three sub-factors (slop, concrete wall, and reinforcing wall). As results of in-field measurement, a CCTV was the most effective facility, and electrical resistivity survey, acoustic sensing, thermal liner sensor, structure inclinometer, rainfall meter, and flowmeter were also highly effective. According to applications of the facilities in the unstable tailings, structural defects were mainly found in the piping, which was the most important monitoring factor for safety management of tailings sites.

A Study on the Selection and Modification of Ground Motion Based on Site Response Analysis (부지응답해석에 기반한 지반운동 선정 및 보정에 관한 고찰)

  • Hwang, Jung-Hyun;Mauk, Ji-Wook;Son, Hyeon-Sil;Ock, Jong-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.5
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    • pp.103-110
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    • 2020
  • In the recent seismic design code KDS 41 17 00, selection and modification procedures of ground motions which are used for nonlinear dynamic analyses were adopted. However, its practical applications are still limited due to the lack of literatures. This paper introduces case studies which used site-response analyses to select and modify ground motions for nonlinear dynamic analyses. Based on the case studies, design criterion for site-response analyses were reviewed thoroughly in the viewpoint of practical applications. It was found that design requirements related with bedrock motions are too conservative that ground motions are selected and modified in the excessive manner. It is especially true for low-rise building structures with period ranges including acceleration-sensitive regions. Even though surface motions have shown appropriate responses, such building structures have to re-select and re-modify ground motions based on pre-analysis procedures rather than post-ones according to the current seismic design code. Also, it was observed that building structures with soft soils under strong ground motions need more comprehensive investigations on soil properties and efficient analysis methods in order to perform site-response analyses. This is due to the fact that lack of reliabilities on soil properties and analysis methods could result in unstable site-responses.

Manufacturing of a Treatment Agent for Corrosion Oxides of Iron Relics (철기 유물 부식 산화물 처리제의 제조)

  • Yang, Eun Hee;Han, Won-Sik;Choi, Kwang-Sun;Hong, Tae-Kee
    • Korea Science and Art Forum
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    • v.30
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    • pp.251-261
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    • 2017
  • Metal is a material that has exerted a lot of influence on the development of human cultures, and has closely connected with our life from the past to the present. Types of metal we have used from the prehistoric times are varied, and iron relics take the largest percentage of metal relics excavated in our country. The biggest threat to the existence of iron relics ranging from excavated relics to the ones that are transmitted is the process of corrosion, and physical removal has been used the most for removing corroded oxides. For details for removal of corrosion oxides, this thesis aimed to research on the chemical corrosion oxides remover that protects parent material of iron relics but treats corrosion oxides only. For safe and effective removal of corrosion oxides of iron relics, this study was conducted aiming at finding the possibility of and optimized composition for removal of iron relics corrosion oxides by manufacturing new acid, alkaline and neutral oxides removers and changing their composition variously, exploring the possibility by applying the agents to modern relics. The results of this study are as follows: First, the acid solution removed only some part of corrosive substance oxidized on the surface of metal specimen. Second, the application of each of alkaline and neutral solution resulted in remaining black-colored corrosive substance, but it was removed when the quantity of the solution and the duration of application are increased. Third, All the three solutions did not cause any damage to parent material in the course of application, and showed the result that they are capable of removing unstable oxide layer while protecting parent material and stable corrosive layer as the solutions would be able to deal with situation by a relic only through the control of concentration of solution and duration of application.

Emulsifying Properties of Gelatinized Octenyl Succinic Anhydride Modified starch from Barley (호화 옥테닐 호박산 전분의 유화 특성)

  • Kim, San-Seong;Kim, Sun-Hyung;Lee, Eui-Seok;Lee, Ki-Teak;Hong, Soon-Taek
    • Journal of the Korean Applied Science and Technology
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    • v.36 no.1
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    • pp.174-188
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    • 2019
  • The present study was carried out to investigate the emulsifying properties of heat-treated octenyl succinic anhydride(OSA) starch and the interfacial structure at oil droplet surface in emulsions stabilized by heat-treated OSA starch. First, the aqueous suspensions of OSA starch were heated at $80^{\circ}C$ for 30 min. Oil-in-water emulsions were then prepared with the heat-treated OSA starch suspension as sole emulsifier and their physicochemical properties such as fat globule size, surface load, zeta-potential, dispersion stability, confocal laser scanning microscopic image(CLSM) were determined. It was found that fat globule size decreased as the concentration of OSA starch in emulsions increased, showing a lower limit value ($d_{32}:0.31{\mu}m$) at ${\geq}0.2wt%$. Surface load increased steadily with increasing OSA starch concentration in emulsions, possibly forming multiple layers. In addition, fat globule sizes were also influenced by pH: they were increased in acidic conditions and these results were interpreted in view of the change in zeta potentials. The dispersion stability by Turbiscan showed that it was more unstable in emulsions at acidic condition. Heat-treated OSA starch found to adsorb at the oil droplet surface as some forms of membrane (not starch granules), which might be indicative of stabilizing mechanism of OSA starch emulsions to be steric forces.

Analysis of Risk Factors in Coronary Artery Bypass Surgery (관동맥우회술의 위험인자 분석)

  • 정태은;한승세
    • Journal of Chest Surgery
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    • v.31 no.11
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    • pp.1049-1055
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    • 1998
  • Background: Coronary artery bypass surgery is an important treatment for ischemic heart disease. Recently operative mortality and morbidity has decreased, however further improvement is necessary. Materials and methods: This study was designed to evaluate the risk of operative mortality and morbidity by retrospective method. From 1992 to 1997, eighty six patients underwent coronary artery bypass surgery. There were 61 males and 25 females aged 36~74 years(mean, 58.6). Fourteen patients(16%) had previous PTCA or stent insertion, 41 patients(48%) had unstable angina, and 45 patients(52%) had three vessel disease. Patients with low LV ejection fraction(<35%) were 7 cases and urgent or emergent operation were 10 cases. There were 6 cases of combined surgery which were mitral valve replacement(2 cases), aortic valve replacement(2 cases), ASD repair(1 case), and VSD repair(1 case). Average number of distal anastomosis was 3.5 per patient and average aortic cross clamp time was 115±38.3min. Preoperative risk factors were defined as follows: female, old age(>70 years), low body surface area(<1.5M2), PTCA or stent insertion history, hypercholesterolemia, smoking, hypertension, DM, COPD, urgent or emergent operation, left main disease, low LV ejection fraction(<35%), and combined surgery. Results: Operative mortality was 7cases(8%). As a postoperative morbidity, perioperative myocardial infarction was 6 cases, cerebrovascular accident 6 cases, reoperation for bleeding 5 cases, acute renal failure 4 cases, gastrointestinal complication 3 cases, and mediastinitis 3 cases. In the evaluation of operative risk factors, low body surface area, DM and low LV ejection fraction were found to be predictive risk factors of postoperative morbidity(p<0.05), and low ejection fraction was especially a risk factor of hospital mortality(p<0.05). Conclusions: In this study, low body surface area, DM and low LV ejection fraction were risk factors of postoperative morbidity and low ejection fraction was a risk factor of hospital mortality.

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Physical properties, released patterns and bio-efficacy of granular mixtures with chlomethoxyfen and butachlor formulated by different methods (제조방식을 달리한 chlomethoxyfen과 butachlor 혼합입제의 물리성, 수중용출도와 생물효과 비교)

  • Chung, Bong-Jin;Yeon, Jae-Heum
    • The Korean Journal of Pesticide Science
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    • v.2 no.3
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    • pp.36-44
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    • 1998
  • To develope cost-effective new granular formulation of mixture with 7.0% chlomethoxyfen and 3.5% butachlor, this study was conducted by investigation of floatability, dispersibility or collapsability and released concentration of active ingredients in water and bio-efficacies of the granules formulated by different formulation methods compared to commercial pellet-extruded granules. They were formulated by coating on or impregnation into extruded pellets, sands and zeolites with two active ingredients, binders, friction reducer, dispersing agents and bentonite. Pellet-coated method showed similar floatability, collapsability and bio-efficacy to the commercial pellet-extruded one or better than that but unstable patterns of released concentration of chlomethoxyfen because of easy isolation of coated technical particles from the surface of granules. Sand-coated methods showed similar physical properties, released pattern of two active ingredients, and bio-efficacy to the commercial one. Liquid binders and/or dispersing agents are more important than powdered ones to control released concentration of active ingredients from the granule mixtures, to improve the floatability and dispersibility, and to show good bio-efficacy. Sand-coated one might be a suitable method if types and amount of liquid binders and dispersing agents are selected.

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Vertical Atmospheric Structure and Sensitivity Experiments of Precipitation Events Using Winter Intensive Observation Data in 2012 (2012년 겨울철 특별관측자료를 이용한 강수현상 시 대기 연직구조와 민감도 실험)

  • Lee, Sang-Min;Sim, Jae-Kwan;Hwang, Yoon-Jeong;Kim, Yeon-Hee;Ha, Jong-Chul;Lee, Yong-Hee;Chung, Kwan-Young
    • Atmosphere
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    • v.23 no.2
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    • pp.187-204
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    • 2013
  • This study analyzed the synoptic distribution and vertical structure about four cases of precipitation occurrences using NCEP/NCAR reanalysis data and upper level data of winter intensive observation to be performed by National Institute of Meteorological Research at Bukgangneung, Incheon, Boseong during 63days from 4 JAN to 6 MAR in 2012, and Observing System Experiment (OSE) using 3DVAR-WRF system was conducted to examine the precipitation predictability of upper level data at western and southern coastal regions. The synoptic characteristics of selected precipitation occurrences were investigated as causes for 1) rainfall events with effect of moisture convergence owing to low pressure passing through south sea on 19 JAN, 2) snowfall events due to moisture inflowing from yellow sea with propagation of Siberian high pressure after low pressure passage over middle northern region on 31 JAN, 3) rainfall event with effect of weak pressure trough in west low and east high pressure system on 25 FEB, 4) rainfall event due to moisture inflow according to low pressures over Bohai bay and south eastern sea on 5 MAR. However, it is identified that vertical structure of atmosphere had different characteristics with heavy rainfall system in summer. Firstly, depth of convection was narrow due to absence of moisture convergence and strong ascending air current in middle layer. Secondly, warm air advection by veering wind with height only existed in low layer. Thirdly, unstable layer was limited in the narrow depth due to low surface temperature although it formed, and also values of instability indices were not high. Fourthly, total water vapor amounts containing into atmosphere was small due to low temperature distribution so that precipitable water vapor could be little amounts. As result of OSE conducting with upper level data of Incheon and Boseong station, 12 hours accumulated precipitation distributions of control experiment and experiments with additional upper level data were similar with ones of observation data at 610 stations. Although Equitable Threat Scores (ETS) were different according to cases and thresholds, it was verified positive influence of upper level data for precipitation predictability as resulting with high improvement rates of 33.3% in experiment with upper level data of Incheon (INC_EXP), 85.7% in experiment with upper level data of Boseong (BOS_EXP), and 142.9% in experiment with upper level data of both Incheon and Boseong (INC_BOS_EXP) about accumulated precipitation more than 5 mm / 12 hours on 31 January 2012.

A Study of Joint Reliability According to Various Cu Contents between Electrolytic Ni and Electroless Ni Pad Finish (전해Ni, 무전해 Ni pad에서의 Cu 함량에 따른 접합 신뢰성에 관한 연구)

  • Lee, Hyun Kyu;Chun, Myung Ho;Chu, Yong Chul;Oh, Kum-Sool
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.3
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    • pp.51-56
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    • 2015
  • It has been used various pad finish materials to enhance the reliability of solder joint and recently Electroless Ni Electroless Pd Immersion Gold (the following : ENEPIG) pad has been used more than others. This study is about reliability according to being used in commercial Electrolytic Ni pad and ENEPIG pad, and was observed behavior of various Cu contents. After reflow, the inter-metallic compound (IMC) between solder and pad is composed of $Cu_6Sn_5$ (Ni substituted) by using EDS, and in case of ENEPIG, between IMC and Ni layer was observed the dark layer ($Ni_3P$ layer). Additional, it could be controlled the thickness of dark layer according to Cu contents. Investigated the different fracture mode between electrolytic Ni and ENEPIG pad after drop shock test, in case of soft Ni, accelerated stress propagated along the interface between $1^{st}$ IMC and $2^{nd}$ IMC, and in case of ENEPIG pad, accelerated stress propagated along the weaken surface such as dark layer. The unstable interface exists through IMC, pad material and solder bulk by the lattice mismatch, so that the thermal and physical stress due to the continuous exterior impact is transferred to the IMC interface. Therefore, it is strongly requested to control solder morphology, IMC shape and thickness to improve the solder reliability.