Cr첨가에 따른 자동차용 소결 밸브시트의 미세조직과 기계적 성질

具原奭,朴種寬,崔昌守,정인상 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.8

Valve seat inserts are used in the valve train area of internal combustion engines. Good wear resistance is needed since repeated stress is applied by the valves under combustion gas atmosphere of high temperatures. Currently, most of the valve seat inserts are being manufactured by P/M route. In this study, the characteristics of materials especially the wear resistance with the addition of Cr-hard particles were investigated. The results of this study are as follows: increase in the Cr-hard particles resulted in a decrease of the density of specimens. Pores formed by Cr diffusion from Cr-hard particles was attributed to the reduction in density. As a result, radial crushing strength was decreased with increase of the Cr-hard particals. Engine simulation test indicated that matrix can be hardened with the addition of Cr-hard particles. The excess addition of Cr-hard particles, however, degrades the wear resistance by the increase of residual pores. Therefore, the appropriate amount of Fe-Cr-C hard particles is 1∼5 wt%.

Quinoline誘導體들의 置換基效果에 關한 吸收分光學的 硏究

具原會,朴鍾會 충남대학교 자연과학연구소 1977 學術硏究誌 Vol.4 No.2

In the present work, the ultra-violet absorption spectra of quinoline and its 17 derivatives with various substituents have been studied and discussions are made in terms of inductive and mesomeric effects derived from the first and second order perturbstion theory upon the wavelenth shift and intensty change of the ^(1)L_(k) and ^(1)L_(a) type bands. In order to calculate the respective wavelength shifts of absorption peaks of ^(1)L_(k)bands of the quinoline derivatives which are caused by the substituent effects, modified and extended method of Longuet-Higgins has been used. The calculated results show good agreement with the experimental data. In the case of the quinoline derivatives which have monosubstituent at 2, 3, 4. 5, 6, 7 and S positions respectively, the a-and β-naphthylmethyl anion models have been proposed for the irterpretation band shifts. It has been found that the above mentioned models are quite suitable proposal. In the explanation of the changes in absorption, intensities due to the substruent effects in some monosubstituent quinolines. an attempt has been made to use the idea of spectrpscopic moment put forward by Platt and Petruska. Qualitative agreement between the above mentioned treatments and the experimental results has been obtained. For the purpose of investigating the relationship between the substituent effects on the spectra and basicity of the quinoline derivatives, basicity of quinoline and its 17 detatives are measured in 46 per cent ethanol aqueous solution by the usual spectrophotometric methods. Basicities of quinoline derivatives are discussed in terms of inductive effect of substituents and, in addition, the applicability of the Hammett equation has been tested.

청주시 도시관광 연구

박구원 청주대학교 경영경제연구소 2016 경상논총 Vol.8 No.2

최근 관광분야에서는 도시관광이나 관광권에 대한 의미가 커지고 있다. 본 연구는, 최근 청원군과의 통합을 통해 새로운 지방거점도시로서 발전해 가고 있는 청주시를 대상으로, 도시관광이 갖는 관광목적지로서의 역할과 발전가능성을, 관광통계 등을 통해 검토한 것에 있다. 연구결과, 지역관광에서 도시관광이 갖는 기능과 역할은 매우 큰 것으로 확인된다. 또한 관련연구와 사례연구를 통해 보면, 이러한 도시관광의 발전에 있어서는 중심상업지역의 역할이 매우 크고, 이들이 하나의 관광활동목적지로서 기능해 나가기 위해서는 숙박교류기반과 테마자원 등을 통해 관광목적지로서의 명확한 이미지와 실체를 확보해 나가는 것이 무엇보다 필요한 것으로 나타난다. 청주시의 경우, 이러한 중심기능이 매우 떨어져 있고, 시설은 분산되어 있어, 도시관광뿐만 아니라 관광목적지로서의 기능이 매우 약한 것으로 나타난다. 그리고 이러한 도시관광의 기능 부족은 충북관광이 활성화되지 못하는 중요한 원인이 되고 있는 것으로 관찰된다. 본 연구에서는 이러한 연구결과를 토대로, 청주시 도시관광이 관광목적지로 발전하기 위한 몇 가지 기본적인 발전방향을 검토했다.

소뇌뇌교각종양에서 수술중 전기생리학적 신경계집중감시의 변화

서대원,박관,안재영,이상구,정진상,홍승봉,이원용,김병준,김종현 대한신경과학회 1999 대한신경과학회지 Vol.17 No.1

近代 帝國主義의 形成과 그 特徵에 관한 小考

尹元求 동국대학교 대학원 1986 大學院硏究論集-東國大學校 大學院 Vol.16 No.-

Recent imperialism has specific characteristics different from the ancient or the medieral imperialism. One of the characteristics is the close relationship between recent imperialism and capitalism, which is the fundamental characteristic of recent imperialism. Economically, we can access to the imperialism in the two ways; liberalist theory & Marxist theory. The difference between the two lies in the defference of viewpoint from which they understand the imperialism. The one think the imperialism as onn of the policy alternatives and the other as the natural consequence of historic change. Since capitalism as a mode of production appeared, economy have been reformed to the capitalist system. In this process, the preceding capitalist countries who have experienced industrial revolution early began to find interests from traditional or underdeveloped countries. And this prevailing imperialism characterized the world economy in the end of 19 century. After the establishment of capitalism, there occurred wars between advanced countries to redivide and to epxand their territory, and as a result, this advanced to the situation of the so called "crisis of capitalism." Imperialism have a close relation with the development stage of capitalism. The advance of capitalism brings about capital concetration and centralization and the resutling monopolistic capital experiences a declining rate of interest, so that the capital searches for a more beneficial opportunities to invest from abroad. This is the very economic mechanism of recent imperialism which reflects the law of capital movements. Consequently, there ocurred many problems in the would economy, and the followings are a few of them. ① Trade off between the past suzerain countries and their colonies. ② Unbalance in trade (South-north problem) resulted from ① the trade off. ③ dependence theory These problems have been resulted from the establishment of recent imperial mechanism but are the principal issues world economy should solve solution.

동종골수이식 후 혈당 및 혈중 지질농도의 변화양상 및 관련인자

이원영,강무일,오은숙,오기원,손현식,윤건호,차봉연,이광우,손호영,강성구,신완식,민우성,김춘주 대한당뇨병학회 2002 Diabetes and Metabolism Journal Vol.24 No.6

연구배경:골수이식은 비교적 젊은 연령의 환자들을 대상으로 하며 면역억제제의 사용기간이 비교적 짧으므로, 주로 고령의 만성 질환 환자에서 시행되는 고형장기이식에서와는 달리 당대사 및 지단백 대사에 있어서 많은 차이점이 있을 것으로 추측된다. 저자들은 전향적 연구를 통하여 골수이식 후 시기별로 혈당 및 혈중지단백 변화 양상을 알아보고 이와 관련된 임상인자들을 규명하고자 하였다. 방법:1998년 10월부터 1999년 8월까지 가톨릭대학교 성모병원에서 동종골수이식을 시행한 환자들 중 43명을 대상으로 이식 전 및 이식 후 1, 2, 3, 4주와 3개월, 6개월에 공복 혈당, 혈중 총 콜레스테롤, 중성지방, 고밀도지단백을 측정하여 골수이식 후 시기별 변화를 관찰하고 여러 임상인자들에 따른 차이를 알아보았다. 결과:1. 공복혈당은 골수이식 수 첫4주 동안 상승하였고 이후 감소하였으나 이식 6개월 시점의 평균 공복혈당은 이식 전보다 유의하게 높게 관찰되었다. 혈중 총 콜레스테롤은 이식 후 1주에 최고치를 형성하였고 이후 기저수준으로 회복되었다가 이식 수 3,6개월에 다시 증가하여 기저치에 비해 유의하게 높았다. 혈중 중성지방은 이식 후 1개월까지 유의하게 증가하였고 이후 감소하여, 3,6개월에는 기저치와 유의한 차이가 관찰되지 않았다. 혈중 고밀도지단백은 이식 후 2,3주에 이식 전보다 유의하게 감소하였고 이후 이식 전 수준으로 회복되었다. 혈중 저밀도지단백은 총 콜레스테롤의 변화와 매우 유사하였다. 2. 골수이식 후 6개월 시점에서 공복 혈당이 126㎎/dL이상인 환자는 7명(16%)이었다. 이들 환자들과 공복혈당 126㎎/dL 미만의 환자 36명을 비교한 결과, 공복혈당이 126㎎/dL 이상인 환자군에서 스테로이드 평균 투여량이 많았고 고밀도지단백이 유의하게 낮았다. 3. 이식편대숙주질환이 발생한 환자는 그렇지 않은 환자보다 이식 후 1, 2, 3주 및 6개월의 총 콜레스테롤이 더 낮았고, 3개월의 공복혈당이 더 높았다. 혈연골수이식 환자군은 비혈연골수이식 환자에 비해 투여된 스테로이드 용량이 더 적음에도 불구하고 이식 후 1, 2, 3주 및 6개월의 총 콜레스테롤 수치가 더 높았다. 스테로이드 고용량 투여군(하루 평균 7.5㎎기준)은 저용량군보다 이식 후 3개월 시점의 공복혈당이 더 높았으나 나머지 시점의 혈당, 혈중 지질농도에 있어서는 유의한 차이가 관찰되지 않았다. 결론:골수이식 후 초기시기에 주로 당 대사 및 지질대사이상이 관찰되며 이는 면역억제제 투여와 관련이 있음을 알 수 있었다. 면역억제제가 고용량 투여되는 합병증 발생 시 이들 대사이상에 관심을 기울여 대처해야 할 것이다. Background: In bone marrow transplantation(BMT), recipients are usually younger and immunosuppressants are open used in shorter period than in solid organ transplantation. Therefore, there might be a difference in glucose and lipid metabolism between BMT and solid organ transplantation. However, the serial changes of metabolic parameters following BMT have not been studied. Therefore, the aim of this study is to investigate the serial changes of blood glucose, lipids and the putative factors that are related with these changes after BMT. Methods: We have prospectively investigated 43 patients who underwent allogeneic BMT. Fasting plasma glucose(FPG), total cholesterol, triglyceride and high-density lipoprotein(HDL) were measured before BMT, and at 1, 2, 3, 4, 12 weeks and 6 months after BMT. The serial changes of these metabolic parameters according to clinical factors including type of BMT, mean daily steroid dosage, and occurrence of graft versus host disease (GVHD) were examined. Results: 1. Mean FPG level increased during 4 weeks after BMT and remained above basal value at post-transplant 6 months. Total Cholesterol level was increased during initial 4 weeks after BMT and was above basal value at post-BMT of 3 and 6 months. Triglyceride level was progressively increased during initial 4 weeks after BMT, but returned to basal value there after. HDL-cholesterol level was significantly decreased during initial 4 weeks after BMT, but returned to basal value there after. 2. Patients with FPG above 126 mg/dL and the other patients, the former received larger amounts of daily steroid and had lower HDL-cholesterol level. 3. The changes of metabolic parameters were different according to type of BMT, steroid dose, and occurrence of GVHD. Conclusion: Although there was increase of FPG, TC, TG and decrease of HDL-C during initial 4 weeks after BMT, these metabolic changes recovered slowly thereafter. Immunosuppressants are thought to be associated with these changes. Further observation will be needed for the long-term effect of BMT on metabolic changes(J Kor Diabetes Asso 24:689~698, 2000).

韓國産 진드기類의 分類學的 硏究 : Ⅱ. 털진드기및 中氣門진드기

李元求 全北大學校 基礎科學硏究所 1980 基礎科學 Vol.3 No.1

3 species of Cheyletid mites and 4 species of Mesostigmatid mites in house dusts and stored food materials as following list were investigated taxonomically from Korea. Suborder Trombidiformes Reuter, 1901 Family Cheyletidae Leach, 1814 1. Cheyletus malaccensis Oudemans, 1904 2. Cheyletus eruditus (Shrank, 1781) 3. Cheletomorpha lepidopterorum(Shaw, 1794) Suborder Mesostigmata Canestrini, 1819 Family Macrochelidae Vitzthum, 1930 4. Macrocheles muscaedomesticae(Scopoli, 1772) Family Dermanyssidae Kolenati, 1859 5. Dermanyssus gallinae(De Geer, 1778) 6. Ornithonyssus bacoti(Hirst, 1913) Family Laelaptidae Berlese, 1892 7. Haemolaelaps casalis Berlese, 1887

韓國産 Phytoseiidae科(거미綱:진드기目)의 分類學的 硏究

李元求,柳面玉 全北大學校 基礎科學硏究所 1991 基礎科學 Vol.14 No.1

본 연구는 捕食性 mite인 Phytoseiidae 科의 분류학적 검토를 목적으로 이루어졌다. 1998년 6월부터 1989년 6월 사이에 주로 호남지역에서 채집된 표본을 정리한 결과, 식물의 잎에서 발견된 것으로는 다음과 같이 5종이 동정되었다. 1) Amblyseius (Amblyseius) deleoni Muma et Denmark, 1971, 2) A. (A.) orientalis Ehara,. 1959, 3) A. (A.) longicornis(Evans, 1952), 4) Phytoseius (Phytoseius) nipponicus Ehara, 1967, 5) P. (P.) blakistoni Ehara. 1966. 그 중 deleoni, P. nipponicus, P. blakistoni의 3종은 한국 미기록종이었다. 본 연구에서의 우점종은 A. deleoni이었다. Three species of phytoseiid mites were previously known to occur in Korea. In these paper, descriptions and records are given of five species of the family as follows. *1. Amblyseius (Amblyseius) deleoni Muma et Denmark, 1971, 2. Amblyseius (Amblyseius) orientalis Ehara, 1959, 3. Amblyseius (Amblyseius) longisinosvs(Evans, 1952), *4. Phytoseius (Phytoseius) nipponicus Ehara, 1962, *5 Phytoseius (Phytoseius) blakistoni Ehara. 1966. Of which, three species with asterisk are new to Korea. Thus, a total of six species, including Typhlodromus vulgaris which is not treated in this paper, are known from Korea.

Identification and characterization of Metarhizium majus isolated from the edible insect Protaetia brevitarsis in Korea

Kwak Kyu‐Won,Aktaruzzaman Md.,Kim Eunsun,Kim Sun Young,Hong Seung‐Beom,Park Ji Yeong,Park Kwanho,Koo Bonwoo,Kim Yong‐Soon 한국곤충학회 2021 Entomological Research Vol.51 No.12

Edible insects are considered novel protein sources, and the edible insect breeding industry is growing rapidly. However, fungal pathogens are a major threat to this industry, and appropriate identification of causative agents is important for the development of antifungal agents. In 2019, strains of the fungal pathogen Metarhizium were isolated from infected second and third instar larvae of the economically important edible insect Protaetia brevitarsis, which were collected from separate farms in Gimhae-si, Gyeongsangnam-do, Korea. Based on morphological characteristics and multilocus phylogenetic analysis of the internal transcribed spacer region, and 50-region of gene encoding the 1-α elongation factor, the fungal strains were identified as Metarhizium majus. Here, we report the detailed phylogenetic characteristics and morphological description of this species, which is prevalent in Korea. Identification of the principal disease-causing agent can help develop disease prevention and antifungal strategies for application in edible insect-rearing farms.

R_2O-MgO-MgF_2-SiO_2계 Glass의 Crystallization에 관한 연구

강원호,박병구 단국대학교 신소재기술연구소 1993 신소재 Vol.3 No.-

본 연구에서는 Fluour mica group^1)의 하나인 Lithium fluorhectorite mica (LiMg_2LiSi_4O_10F2) 결정상^2)을 얻기위해 Li_2O-MgO-MgO-MgF_2-SiO_2계를 기본 조성으로 선정하여Tdmaum 결성화시켰을때에 나타나는 벽개성(cleavage)의 원인을 mica의 결정구조 XMg_2LiSi_4O_10F2에서 interlayer cation에 있는 것으로 보고서 X에 해당하는 R_2O성분 LI_2O, Na_2O, K_2O를 4∼10 wt% 변화시켜 Pt-crucible을 사용하여 1450℃에서 모유리를 제조하였다. 제조된 모유리의 DTA, TMA 열분석 결과를 토대로, 결정화 열처리를 핵형성 610∼690℃, 결정성장 900∼1150℃, 각각 2시간, 4시간으로 결정화 sample을 얻었으며 XRD와 SEM을 사용하여 결정상과 미세 구조를 분석하였다. Tg는 520℃, Mg는 580℃였으며, 모유리 상태는 부분 유백의 모유리를 얻을 수 있었다. 최적 결정화 조건은 핵형성 630∼670, 결정성장 1100℃였으며 결정상은 Lithium (Sodium, Potassium) fluorhectorite 와 talc, 그리고 quartz였다. 벽개성이 가장 우수한 조성은 Li_2O 6 wt%, MgO 10.8 wt%, MgF_2 16.7 wt%, SiO_2 6.4 wt% 였다. In this study, the crystallization of R_2O-MgO-MgF_2-SiO_2 fluormica glass-ceramics were investigated. Lithium fluorhectorite mica (LiMg_2LiSi_4O_10F_2), one of the water swelling mica group is composed of Li_2-O-MgO-MgF_2-SiO_2 glass system and this composition added TiO_2, ZrO_2 and P_2O_5 as nucleating agent. The interlayer cation Li^+ of the composition was replaced by Na^+ -and K^+ -ions. this base glass was melted at 1450℃ per 1h. After heat-treatment on the bases of thermal analysis of this base glass by DTA and TMA, crystal phase and sizes upon to the nucleation and crystallized temperature were observed by XRD and SEM. When crystallized, the crystal phase is lithium fluorhectorite, talc and quartz. It is found that the crystal phase to influence self delamination is lithium fluorhectorite one. In the case of substitution of interiayer cation Na^+ and K^+ for Li^+, properties of cleavage and delamination was not found and also crystal phase containing Li^+ is different from one of that Na^+, K^+. The optimum chemical composition are LI_2O 6 wt%, MgO 10.8 wt%, MgF_2 16.7wt%, SiO_2 66.4 wt% and the optimum temperature for crystallization having excellent delamination is 1100℃ and nucleation for temperature is 630℃ -670℃. When used TiO_2 as a nucleating agent, it show excellent crystallization.