• Journal of the Korean Ceramic Society
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• v.41 no.4
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• pp.334-339
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• 2004

Microstructures and mechanical properties of SPSed monolithic HAp, HAp-Ag, and HAp-ZrO$_2$sintered bodies were investigated by the XRD, SEM, and TEM techniques. The nano-sized HAp powders were successfully synthesized by precipitation of Ca(NO$_3$)$_2$4$H_2O$ and (NH$_4$)HPO$_4$solution. In the HAp-Ag composite, the shrinkage cavities were observed at the interfaces between HAp and large sized Ag particles due to the mismatch of their thermal expansion coefficients. However, no found the defect at the interfaces between HAp and fine-sized Ag particles. In the HAp-ZrO$_2$composite. nano-sized ZrO$_2$particles were almost dispersed at the grain boundaries of HAp phase. The fracture toughness of HAp-Ag and HAp-ZrO$_2$ composites were increased due to the plastic deformation and phase transformation mechanisms of the dispersed fine Ag and ZrO$_2$phase in the HAp matrix, respectively.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.196-215
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• 2007

The Representatives of Korea & India hold The Sixth negotiation for conclusion of Korean-India CEPA(Comprehensive Economic Partnership Agreement) at IFANS(Institute of Foreign Affairs & National Security) in Seoul at April 4, 2007. The latest, India is paid attention by the citizen of the world as the leading country that it lead the 21C's world economic with the China, India is called one of the BRICs and Chindia countries. Now, the concern of the citizen of world inclines huge potential energy of India. It is that time, we must change our concern from Chinas to India slowly. This paper put emphasis the point that we have to move switch over the focus of our study from to India, now.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.478-481
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• 2000

Single phase $Pb(Mg_{1/3}Nb_{2/3})O_3$ ceramics doped by 10 mol% of electron donors such as $La^3,\; Pr^{3+,4+},\; Nd^{3+},\; Sm^{3+}$, were synthesized and their B-site cationic ordering structures were investigated by XRD and TEM. In the XRD patterns, only fundamental reflections were observed for the undoped $Pb(Mg_{1/3}Nb_{2/3})O_3$, while the (h/2 $\textsc{k}$/2ι/2)(h,$\textsc{k}$,ι all odd) superlattice reflections resulting from the 1:1 ordering induced unit cell doubling were also observed for the donor-doped $Pb(Mg_{1/3}Nb_{2/3})O_3$. In the TEM selected area diffraction patterns, the (h/2 k/2 l/2)(h,k,l all odd) superlattice reflection spots as well as the fundamental reflection spots were observed for all the samples, but the relative intensities of the superlattice reflection spots to the fundamental reflection spots were significantly enhanced by the donor-doping. In the TEM dark-field images, antiphase boundaries were observed only for the donor-doped $Pb(Mg_{1/3}Nb_{2/3})O_3$. It was therefore experimentally verified that doping by electron donors such as $La^3,\; Pr^{3+,4+},\; Nd^{3+},\; Sm^{3+}$, enhances the B-site cationic 1:1 ordering in $Pb(Mg_{1/3}Nb_{2/3})O_3$. These experimental results were interpreted in terms of the charge compensation mechanism.

• Journal of The Korean Association For Science Education
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• v.24 no.5
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• pp.946-958
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• 2004

The purpose of this study was to investigate factors in school science influencing students' attitudes toward science. In order to achieve the purpose, a total of 1,002 students at 5th, 7th, and 10th grade levels was sampled and surveys were carried out to examine attitudes toward science and reasons that students liked and disliked science. According to the results, male students liked science more than female students did at all grade levels and 10th graders liked science less than 5th and 7th graders did. The main reason that students liked science was experiments. And the main reason that students disliked science was science teaching methods including science activities, instructional materials, science textbooks and science teachers. Among the reasons that students liked science, factors that affected attitudes toward science were contents and characteristics of science subjects and experiments. Among the reasons that students disliked science, factors that affected attitudes toward science were experiments and science teaching methods. The results suggest that it is desirable to apply appropriate methods according to students' interests in science to develop positive attitudes toward science effectively.

• KDI Journal of Economic Policy
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• v.19 no.2
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• pp.73-157
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• 1997

19세기(世紀) 중반(中盤)에 시작된 선진국(先進國)들의 공업화(工業化)는 약 100년이 소요(所要)되었는데 동(東)아시아 신흥공업국(新興工業國)(NICs)들의 경우에는 20~30년이 소요(所要)된 것으로 추정된다. 후자(後者)의 공업화(工業化) 경험은 흔히 '동(東)아시아의 기적(奇蹟)'이라 불린다. 그러나 이 고속성장(高速成長) 혹은 압축성장(壓縮成長)이 가능했던 이유가 무엇이냐에 관해 경제학계(經濟學界) 내외(內外)에서 그리고 국내외(國內外)에서 일치된 의견이 없고, 특히 이 과정에서의 정부(政府)의 역할(役割)을 어떻게 평가하느냐에 관하여는 더욱 그러하다. 신고전(新古典) 경제학(經濟學)은 이 나라들의 가격왜곡(價格歪曲)의 최소화(最小化), 시장기구(市場機構)의 활용(活用), 국제분업(國際分業)에의 참여(參與)에서 주된 이유를 찾고 있는데 비해, 소위 수정주의(修正主義)는 이같은 견해가 사실과 크게 괴리가 있으며 '기적(奇蹟)'은 시장(市場)의 자원배분(資源配分)에 대한 정부개입(政府介入)이 주효(奏效)하였기 때문이라 주장한다. '동(東)아시아의 기적(奇蹟)'은 동(東)아시아란 지역(地域)에서 일어난 현상일 뿐 아니라 20세기(世紀) 후반(後半)에 일어난 동시대적(同時代的) 현상이기도 하다. 공업화(工業化)를 이룬 나라들은 모두 세계시장(世界市場)과 활발히 교역(交易)하였다는 공통점이 있는데, 세계시장(世界市場)의 규모(規模)를 대표하는 세계총수출(世界總輸出)이 19세기(世紀) 중반(中盤)과 20세기(世紀) 후반(後半) 사이에 실질기준(實質基準)으로 100배 이상 커졌다. 이 글은 세계시장(世界市場)의 규모증대(規模增大)가 동(東)아시아 NICs들의 고속성장(高速成長)의 이유(理由)였을 가능성(可能性)을 이론적(理論的)으로, 실증적(實證的)으로 검토해본 것이다. 이론적(理論的)으로는, A Lewis의 무한노동공급(無限勞動供給)(unlimited supply of labor)이 존재하는 경제(經濟)에서는 세계시장((世界市場) 상대가격(相對價格)이 불변(不變)인 한 제조업내(製造業內) 노동집약도(勞動集約度)가 높은 산업(産業)에 대한 투자유인(投資誘因)이 지속된다는 점에 고속성장(高速成長)의 근거가 있다고 보았다. 이러한 투자(投資)의 지속은 제조업부문(製造業部門)의 산출(産出)과 고용(雇傭)이 경제(經濟)에서 점하는 비중(比重)을 낮은 자원비용(資源費用)으로 증대(增大)시킬 것이기 때문이다. 실증분석(實證分析)에서는, 필요한 통계자료(統計資料)가 있는 19개국의 공업화(工業化) 경험(經驗)을 검토하였는데, 한 나라가 공업화(工業化)를 시작하는 시점(時點)의 세계총수출(世界總輸出)이 클수록 그 나라의 공업화(工業化) 소요기간(所要期間)이 단축(短縮)된다는 매우 확실한 증거가 있었다. 또한 동(東)아시아 NICs의 공업화(工業化) 소요기간(所要期間)이 선진국(先進國) 경험에 비해 약 1/4의 길이로, 혹은 그보다 더 짧게 단축(短縮)된 것은 거의 모두 세계총수출(世界總輸出) 규모(規模)의 증가(增加)로 설명될 수 있었다. 이같은 이론적(理論的) 근거(根據)와 실증적(實證的) 증거(證據)를 감안할 때, 우리 경제(經濟)는 정부주도형(政府主導型)이었으나 고속성장(高速成長)을 가능하게 한 것은 정부주도(政府主導)보다는 그 규모(規模)가 대폭 증대한 세계시장(世界市場)에서의 국제분업(國際分業)이었다.

• Journal of the Korea Institute of Building Construction
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• v.23 no.2
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• pp.175-185
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• 2023

Upon analyzing labor productivity in the construction industry across OECD countries, it was found that in 2019, labor productivity per employee in the South Korean construction industry was lower than that of major developed countries when adjusted for purchasing power parity(PPP). Specifically, when benchmarked against other countries at a base of 100, South Korea scored 76.9 in the United States, 88.4 in Japan, and 85.1 in the OECD average. Notably, South Korea ranked 25th in labor productivity per employee in the construction industry among 35 OECD countries in 2019, indicating a low standing. A comparative analysis of the construction market size and labor productivity in the construction industry across OECD countries revealed that larger construction markets did not necessarily correlate with higher labor productivity. To enhance labor productivity in the construction industry, this study proposed the active implementation of smart construction technology at construction sites and the promotion of on-site assembly work using off-site construction(OSC) technology, rather than traditional on-site labor. Moreover, it was recommended that the development of modular construction methods and technologies be expanded. In the future, if off-site production methods and modules are further developed through advanced robotics and factory automation, labor productivity is anticipated to increase due to the restructuring of production methods, such as manufacturing.

• Korean Journal of Materials Research
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• v.7 no.4
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• pp.347-353
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• 1997

BaTiO$_{3}$물질은 뛰어난 유전체로 널리 알려져 왔으며 특히 Heywang등이 제안한 PTCR특성은 이 물질의 응용범위를 세라믹 필터, 회로보호소자, 온도감지소자 및 저항가열장치 등으로 확대시켰다. 이러한 특성의 발현기구는 아직까지 밝혀지지 않은 상태이지만 제 특성을 향상시키기 위한 노력은 계속되어왔다. 특히 개발목적에 맞게 온도에 따른 정저항 특성(PTCR; Positive temperature constnat of resistivity phenomena)을 설계하려는 시도가 계속되어 왔으며 그 중에서도 페로브스카아트계의 2가와 4가의 양이온 자리를 등가나 원자가가 다른 양이온으로 치환하여 특성을 개선하려는 시도가 계속되어 왔다. 특히 $Ca^{2+}$나 Sr$^{2+}$는 $Ba^{2+}$자리를 치환할 수 있는 물질로 개별적인 첨가에 대한 연구는 많은 연구자들에 의해 진행된 상태이지만 최종적인 영향이나 해석에 대해서는 연구자들간에 이견이 많은 상태이다. 이번 실험에서는 BaTiO$_{3}$계에 합성한 (Ca, Sr)TiO$_{3}$를 Ca와 Sr의 상대적인 비를 변화시키면서 전체적인 첨가량을 변화시켜 그에 따른 전기적 특성 및 미세구조를 살펴보았다. (Ca, Sr)TiO$_{3}$의 첨가로 상온저항 및 PTCR특성을 변화시킬 수 있었으며 이를 통해 PTCR물질의 활용범위를 넓힐 수 있는 발판을 마련할 계기가 되었다. 특히 기존의 연구가 주로 개별적인 Ca나 Sr의 첨가에 의한 미세구조와 전기적 특성변화의 연구에 치중해 있었던 것과는 달리 Sr과 Ca을 함께 치환하여 상대적인 비가 특성에 더 중요한 영향을 끼치는 것을 확인하였으며 적절한 합성비를 선택하면 퀴리온도에서의 저항변화폭을 유지하면서 상온저항을 낮출 수 있음을 확인하였다.문했던 연구소인 Shanghai Research Center of Biotechnology, Shanghai Institute of Industrial Microbiology 및 Scientific Research Institute of Food and Fermentation Industry을 소개하고저 한다. 짧은 기간의 방문이라 주로 해당연구소의 자체소개 자료를 중심으로 방문하면서 느낀점을 기술하고저 한다.초염기성암 기원의 사문암이 열수변질작용을 받아 생성되었음을 명확하게 지시하며, 따라서 활석 광석내에 존재하는 녹니석은 활석의 근원 광물로서 녹니석편암 및 녹니석 편마암 매의 녹니석이 활석화되고 남은 잔존광물이 아니라, 주변암에 의해 성분상의 영향을 받은 열수와 사문암과의 변질교대작용에 의한 활석화과정 중에 주로 생성된 것으로 추정된다. 이러한 결과는 연구지역의 활석광상이 초염기성암의 사문암화 작용과 활석화 작용의 두 가지 변질작용에 의해 형성되어졌음을 알려준다.농도 증가 없이 폐 조직에 약 50배 정도의 고농도 cisplatin을 투여할 수 있었으며, 또한 분리 폐 관류 시 cisplatin에 의한 직접적 폐 독성은 발견되지 않았다이 낮았으나 통계학적 의의는 없었다[10.0%(4/40) : 8.2%(20/244), p>0.05]. 결론: 비디오흉강경술에서 재발을 낮추기 위해 수술시 폐야 전체를 관찰하여 존재하는 폐기포를 놓치지 않는 것이 중요하며, 폐기포를 확인하지 못한 경우와 이차성 자연기흉에 대해서는 흉막유착술에 더 세심한 주의가 필요하다는 것을 확인하였다. 비디오흉강경수술은 통증이 적고, 입원기간이 짧고, 사회로의 복귀가 빠르며, 고위험군에 적용할 수 있고, 무엇보다도 미용상의 이점이 크다는 면에서 자연기흉에 대해 유용한 치료방법임에는 틀림이 없으나 개흉술에 비해 재발율이 높고 비용이 비싸다는 문제가 제기되고 있는 만큼 더 세심한 주의와 장기 추적관찰이 필요하리라 사료된다.

• Journal of Society of Preventive Korean Medicine
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• v.9 no.2
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• pp.59-75
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• 2005

The experiments were undertaken to evaluate the effects of Bosaengtang in pregnant rats and fetuses. Female Sprague-Dawley rats were orally administered with Bosaengtang at the dose of 5mg/kg/day for 20 days. Pregnant rats were sacrificed at the 20th day of gestation, and observed internal and reproductive organs. Fetuses were randomly selected and fixed in 95% ethanol. Fetuses were stained with alcian blue and alizarin red S, and observed skeletal malformations. The results obtained were as follows : Bosaengtang administered group showed higher maternal body weight than the control group, but both groups showed increase in weight. Bosaengtang administered group showed lower than the control group, and higher liver and kidney weight than the control group, but the differences were minimal. There were no significant changes between the control and treated group in blood chemistry values and hematological values but all the groups were within in normal ranges. There were no significant changes in the number of corpus luteum, implantation, live fetus and implantation rate, delivery rate, late resorption rate, sex ratio, but Bosaengtang administered group showed higher early resorption rate than control group. comparing the control and Bosaengtang group, neonatal body weight and the number of fetuses were increased in Bosaengtang group. The fetuses of dams treated with Oriental medicine didn't showed external malformation. Vertebral and sternal variations were observed in Bosaengtang group, but the differences were not apparent compared to the control group. The number of ribs, cervical, thoracic and lumbar vertebrae were normal. The number of sacral was similar and the number of caudal was increased. Fetuses showed significant difference in the number of caudal vertebrae. (P<0.01) From these results, we can carefully conclude that Bosaengtang showed beneficial effects on maternal body weight, early resorption rate, number of live fetus. There were no significant changes in organ weight, hematoscopy, reproduction organs. External malformation wasn't visible. Skeletal variations were showed in vertebrae and sternum but compared to the control group, these variations weren't much different.

• Food Science of Animal Resources
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• v.27 no.1
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• pp.122-126
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• 2007

Expenditure on meat and meat products has been increased in Korea due to the increase of income and the change of diet. From raising farm animals to eating the meat, various hazardous elements can make their ways into the meat and meat products. Recently the issues on food safety and hygiene are drawing a lot of attention, and the current system for managing the safety of foods is still needed to be improved. This survey was aimed to monitor the current situation of country-of-origin labels and hygiene for the meat markets at 4 regions Korea. The survey was performed by collecting samples from whole- sale and retail stores in the nation, which were selling beef. The markets were divided into groups as to territory and the size of the market (Large size, Medium size, and Small size). In terms of size distribution, small butcher shops occupied the highest percentage. On the itemized suitability test of unpacked and packed beef, all the market of 4 regions showed good agreements. However, such labels indicating the methods of cooking and storage were not properly posted on the products. Especially for Ho-nam region, corrections are needed. The results of monitoring sanitation conditions for the butcher shops at 4 regions in Korea showed relatively low suitability. Especially, there were serious lack of knowledge about wearing the sanitation clothing, caps, and shoes. The problem with food safety is so complicated that producer, consumer, food manufacturer, the press, the government, and scholar should solve altogether. It is necessary to educate farmers, food handlers, consumers, etc. and provide them with an accurate information and knowledge.