• Journal of Welding and Joining
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• 제20권6호
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• pp.30-30
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• 2002

It has been reported that the creep characteristics on weldment which is composed of weld metal(W.M), fusion line(F.L), heat-affected zone(HAZ), and base meta(B.M) could be unpredictably changed in severe service conditions such as high temperature and high pressure. However, the studies done on creep damage in power plant components have been mostly conducted on B.M and not the creep properties of the localized microstructures in weldment have been thoroughly investigated yet. In this paper, it is investigated the creep characteristics for three microstructures like coarse-grain HAZ(CGHAZ), W.M, and B.M in X20CrMoV121 steel weldment by the small punch-creep-(SP-Creep) test using miniaturized specimen(l0×10×0.5mm). The W.M microstructure possesses the higher creep resistance and shows lower creep strain rate than the B.M and CGHAZ. In the lower creep load the highest creep strain rate is exhibited in CGHAZ, whereas in the higher creep load the B.M represents the high creep strain rate. The power law correlation for all microstructures exists between creep rate and creep load at 600℃. The values of creep load index (n) based on creep strain rate for B.M, CGHAZ, and W.M are 7.54, 4.23, and 5.06, respectively and CGHAZ which shows coarse grains owing to high welding heat has the lowest creep loade index. In all creep loads, the creep life for W.M shows the highest value.

• 지적과 국토정보
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• 제49권2호
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• pp.67-82
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• 2019

이 연구의 목적은 국내 스마트도시의 이슈와 인식변화를 분석해보는 것이다. 이를 위해 먼저 빅데이터 분석플랫폼을 기반으로 스마트도시 관련 빅데이터 분석을 시행하여 연도별 주요키워드, 워드클라우드, 연도별 스마트도시 키워드 발생빈도 등을 도출하였다. 둘째, 연도별 주요키워드를 메타키워드기반으로 분류하여 그 추이와 흐름을 분석하였다. 셋째, 스마트도시에 대한 감성인식 흐름, 주요 감성키워드를 도출하였다. 분석결과, 과거의 U-City가 대부분 신도시 위주의 인프라 조성 중심이었다면 최근의 스마트도시는 시민이 주도하는 지속가능한 도시건설에 집중하고 있는 것으로 나타났다. 또한 과거에는 인프라, 서비스, 기술 분야가 강조되었다면, 최근에는 관리운영, 방법론 등이 강조되고 있으며 스마트도시에 대한 긍정적 인식도 점차 확산되고 있는 것으로 분석되었다. 이 연구는 국토전역에 스마트도시 서비스가 구축되고 있는 현재 시점에서 국내 스마트도시의 과거와 현재, 미래를 내다볼 수 있는 기초자료로 활용될 수 있을 것이다.

• 공학교육연구
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• 제14권4호
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• pp.11-19
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• 2011

본 연구의 목적은 공과대학생을 위한 교수학습 전략에 대한 시사점을 도출하기 위해 공과대학 신입생의 학습양식과 학습전략 수준을 검토하고, 학습양식에 따른 학습전략 활용 정도를 분석하였다. 서울에 소재한 K대학교와 H대학교의 1학년생 273명을 대상으로 분석한 결과, 감각형, 시각형, 숙고형, 순차형이 더 높은 비율을 차지하였다. 학습전략은 3.28점(SD=0.38)으로서 평균 수준이었으며, 상대적으로 초인지 영역의 수준이 가장 높고, 내적관리 영역 수준이 가장 낮은 것으로 나타났다. 한편, 학습양식에 따른 학습전략 수준의 차이를 분석한 결과, 정보처리 차원에서 학습전략의 유의한 차이가 나타났는데 적극적 학습자의 학습전략 수준이 높은 것으로 나타났다. 세부 전략에서는 인지 영역과 내적/외적관리 영역에서 학습양식별 유의한 차이를 보였다. 본 연구 결과에 기초하여 공과대학의 교수전략 및 학습전략에 대한 시사점을 도출하였다.

• 한국식품과학회지
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• 제17권6호
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• pp.447-453
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• 1985

숙성중 무우 김치 조직의 연부현상을 방지하기 위하여 예비열처리와 $CaCl_2$의 효과를 조사하고 이를 이용하여 무우조직의 경도가 높은 김치를 제조하였다. 무우조직중의 펙틴분해효소인 폴리갈락투로나제(PG)는 펙틴에스테라제(PE)보다 더 낮은 농도의 $CaCl_2$에서 저해되었고, PE의 최적온도는 $50{\sim}55^{\circ}C,$ PG는 $45^{\circ}C$이었다. 따라서 0.05M $CaCl_2$용액에서 $55^{\circ}C$로 2시간동안 열처리 하여 PE는 활성화 시키고 PG는 억제시킬 수 있었다. 최적조건하에서 예비열처리를 하여 김치를 제조한 후 냉장고($4{\sim}10^{\circ}C$에서 저장하려면 pH, 환원당, 경도, 펙틴분해효소의 역가 그리고 펙틴물질의 변화를 측정하였다. 처리구의 무우김치는 비교구보다 숙성중 계속해서 높은 경도를 유지하였고 조직내에 있는 PE는 숙성중 계속 감소하였으며 PG는 초기에는 감소하다가 저장 말기에 가서는 증가하였다. 저장중 펙틴물질 조성의 변화는 비교구가 처리구에 비해 열수가용 펙틴질이 더 많이 증가하였으며 Sodium hexa meta phosphate soluble 펙틴은 더 많이 감소하였다.

• 대한수학교육학회지:학교수학
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• 제5권4호
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• pp.477-506
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• 2003

본 연구는 중학교 3학년 학생들이 문자와 식, 방정식, 함수에 대한 문제 해결과정에서 미지수, 변수, 매개변수로 사용되는 문자의 의미를 어떻게 이해하고 있는지를 살펴봄으로써, 매개변수로서 문자가 이해되는 과정을 분석한다. 그리고 학생들이 문제를 해결할 때 매개변수로서의 문자의 의미를 이해하면서 유연하게 변환할 수 있도록 메타인지 사고전략을 활용한 수업 설계 모형인 '자기질문에 의한 자기조정형 수업모형을 제안한다. 분석결과, 학생들은 문제의 문맥에서 매개변수의 역할을 미지수, 변수의 역할과 비교해 볼 때 매개변수는 상수를 대신하는 문자로 인식하는 경향이 강했으며, 주어진 방정식의 매개변수였던 문자는 구문론적 조작을 거치면서 변수나 미지수의 역할로 변환하는 경우에 그 의미와 역할을 불확실하게 이해하고 있었다. 그리고, 문맥상 매개변수의 의미를 파악하여 생각하기보다는 문맥의 전후관계를 살피지 않고 연산과 기호조작을 이용하여 파악하는 경향이 강했으며, 직선의 그래프로 제시했을 때 학생들은 매개변수의 의미를 좌표평면 상에서 직선의 위치를 결정하는 요소로서 해석하는 능력이 부족하였다.

• 한국전문물리치료학회지
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• 제19권2호
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• pp.69-79
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• 2012

Importance of the work-related musculoskeletal disorders (WMSDs) has been increasing in the hospital industry such as health care industry and financial industry. This study investigated in order to identify the factors like general, occupational and ergonomically characteristics of the subjects related to musculoskeletal disorders (MSDs) of physical therapists (PTs). Ergonomic tools of rapid upper limb assessment (RULA) were used for evaluation workload of the tasks. Prevalence of MSDs were 13 PTs (26.0%) for neck, 31 PTs (62.0%) for shoulder, 9 PTs (18.0%) for arm/elbow, 27 PTs (54.0%) for hand/wrist, 28 PTs (56.0%) for back, 14 PTs (28.0%) for leg/foot. The analysis of the rate of the pain intensity showed that 53.5% subjects experience moderate pain and 14.0% subjects experience severe pain. Factors which were general characteristics, for example, height, ergonomically characteristics such as 'Posture Score A' were related musculoskeletal subjective symptoms in logistic analysis (p<.05). Among physical therapists, action level of RULA were action level 2 (6.0%), action level 3 (52.0%), action level 4 (42.0%). Physical therapists were estimated one of the highest risk factor in this study. This study suggested that the need of preventive education and program for PTs (physical therapists). Comprehensive and systematic management plans should be established to include both ergonomic and sociopsychological aspects.

• 약학회지
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• 제40권1호
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• pp.25-35
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• 1996

Magaldrate. an antiacid was synthesized by reacting magnesium oxide, aluminum sulfate, and dried aluminum hydroxide gel. The optimum synthesis conditions based on the yield of t he product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of Magaldrate were as follows: Reaction temperature; 61~$85{\circ}C$, concentration of two reactants. Mgo and $Al(OH)_3$: 16~19.8%, molar concentration ratio of two reactants, [MgO]/[$Al(OH)_3$]; 4.2~5.0, temperature of washing water; 36~$41^{\circ}C$ and drying temperature of the product: 76~$80^{\circ}C$. Magaldrate was synthesized under the optimum synthesis conditions and identified by analyzing the chemical composition, and by differential scanning calorimetry and X-ray diffraction method. The Magaldrate sample synthesis under these conditions was used to prepare 15.6% Magaldrate original suspension which was utilized to make 13% Magaldrate suspension dispered in various concentrations of eight types of suspending agents. The acid-neutralizing capacity of 13% Magaldrate suspension dispersed in 0.25% suspending agents was examined by Rosset-Rice method. The maximum pH was reached within 1 minute in all suspension tested, and duration maintained between pH 3~5 was decreased in the order of Na alginate Na silicate(meta) Veegum HV pectin agar>Na>CMC>xanthan gum>bentonite. It was found that the hysteresis loop area was increased with temperature in the case of Riopan Plus and the addition of agar, whereas the area was decreased with temperature in the case of the addition of Na alginate and xanthan gum. 13% Magaldrate suspension tends to sediment by the addition of bentonite.

• Journal of Welding and Joining
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• 제20권6호
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• pp.754-761
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• 2002

It has been reported that the creep characteristics on weldment which is composed of weld metal(W.M), fusion line(F.L), heat-affected zone(HAZ), and base meta(B.M) could be unpredictably changed in severe service conditions such as high temperature and high pressure. However, the studies done on creep damage in power plant components have been mostly conducted on B.M and not the creep properties of the localized microstructures in weldment have been thoroughly investigated yet. In this paper, it is investigated the creep characteristics for three microstructures like coarse-grain HAZ(CGHAZ), W.M, and B.M in X20CrMoV121 steel weldment by the small punch-creep-(SP-Creep) test using miniaturized specimen($10{\times}10{\times}0.5mm$). The W.M microstructure possesses the higher creep resistance and shows lower creep strain rate than the B.M and CGHAZ. In the lower creep load the highest creep strain rate is exhibited in CGHAZ, whereas in the higher creep load the B.M represents the high creep strain rate. The power law correlation for all microstructures exists between creep rate and creep load at $600^{\circ}C$. The values of creep load index (n) based on creep strain rate for B.M, CGHAZ, and W.M are 7.54, 4.23, and 5.06, respectively and CGHAZ which shows coarse grains owing to high welding heat has the lowest creep loade index. In all creep loads, the creep life for W.M shows the highest value.

• Restorative Dentistry and Endodontics
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• 제26권2호
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• pp.111-120
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• 2001

Calcium hydroxide pastes is widely used in conventional endodontics. Along with the expanded clinical use of calcium hydroxide, literatures suggest mixing calcium hydroxide with other substance. Among added substances the vehicle plays the most importance role in the overall process because it is directly related with the velocity of ionic dissociation of $Ca^{2+}$ and OH ion. In this study, we evalutated and compared periapical tissue response and root resorption after canal was filled with mixture of saline and calcium hydroxide(Junsei Chemical Co.. Japan) as a aqueous vehicle, Metapaste(Meta Co., Korea) as a viscous vehicle paste, Vitapex(Neo Dental, Japan) as a oily vehicle paste and IRM(Caulk Dentsply, USA) in replantation of rat molar. A total of 31 maxillary first molars of Sprague-Dawley female rats, 30 days old were used. The upper 1st molar was extracted and the mesiobuccal canal was filled with mixture of saline and calcium hydroxide, Metapaste, Vitapex. IRM and then replanted. Rats were sacrificed 3 weeks after replantation. the maxillae were removed. section of 4 micron were cut and stained with hematoxylin-eosin, Apical tissue response were observed under light microscope. The results were as follows: 1. Saline mixing group and Metapaste group were significant different in fibrous capsule width compared to Vitapex group and IRM group(P<0.05). 2. Saline mixing group. Metapaste group. Vitapex group and IRM group did not prevent root resorption and there were no statistical difference. 3. In saline mixing group and Metapaste group. loss of pastes were observed in all samples. From the results of our study. we observed loss of pastes in saline mixing group and Metapaste group because of water soluble property and assumed it was related to inflammation in apical area and sealing ability of material. So, we should study and develop calcium hydroxide vehicle which is easily removed and more stable and because of only 3 weeks observation we need more evaluation in long period.

• Archives of Pharmacal Research
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• 제16권3호
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• pp.219-226
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• 1993

For the analysis of structure relationship of ar-turmerone analogues, the compounds containing the various substituents on the phenyl ring and 1(or 2)-naphthyl group in the place of phenyl of ar-turmerone were prepared and tested their cytotoxicity against HL-60, K-562, and L1210 leukemia cells in vitro. The substituents at para position are methoxy, phenoxy, methyl, trifluoromethyl, fluoro, and chloro. At meta position methoxy, methyl, trifluoromethyl, or chloro groups at ortho position mathoxy or chloro group were introduced. Against HL-60 and K-562 cells, $ED_{50}$ values of the analogues are ranged from 0.8 to $30.0\;\mu{g/ml}$. Againste L1210 cell, these are located more than $20.0\;\mu{g/ml}$. However, 5-carbone-thoxy-2-methyl-6(1-naphthyl)-2-octen-4-one (5n)possesses $ED_{50}$ valuses 0.8, 2.1, $6.5\;\mu{g/ml}$ against HL-60, L1210 cells, respectively. The electronic nature of the substituents on phenyl ring of ar-tumerone dose not affect the biological activity. Therefore the flat structure of aromatic potion of ar-tumerone analogues is the more important factor for their activity rather than its electronic nature. The potentiation of the cytotoxicity with the enlargement of aromatic ring region also supports the importance of the plane structure of this area. The restriction of the single bond rotation between C-6 and aromatic ring through the introduction of substituents at the ortho position of phenyl ring and the increment of size of alkyl group at C-6 position enhances the activity. Therefore the effective conformation should by the one having the orthogonal arrangement between the aromatic ring and the side chain.