Step Free Energy Change and Microstructural Development in BaTiO₃-SiO₂

Chang, Jaem Yung,Kang, Suk Joong L. Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.352 No.-

<P>The effect of step free energy on the grain growth behavior in a liquid matrix is studied in a model system BaTiO3-SiO2. BaTiO3-10SiO2 (mole %) powder compacts were sintered at 1280°C under various oxygen partial pressures (PO2), 0.2, ~ 10-17 and ~ 10-24 atm. As the step free energy decreases with the reduction of PO2, it was possible to observe the change in growth behavior with the reduction of the step free energy. At PO2 = 0.2 atm, essentially no grain growth (stagnant grain growth) occurred during sintering up to 50 h. At PO2 ≈ 10-17 atm, abnormal grain growth followed stagnant grain growth during extended sintering (incubation of abnormal grain growth). At PO2 ≈ 10-24 atm, normal grain growth occurred. These changes in growth behavior with PO2 and the step free energy reduction are explained in terms of the change in the critical driving force for appreciable growth relative to the maximum driving force for grain growth. The present experimental results provide an example of microstructure control in solid-liquid two- phase systems via step free energy change.</P>

시뮬레이션 평가 기준 및 방법에 따른 창세트 열관류율 비교

강혜숙(Kang, Hye-Suk),유동철(Yoo, Dong-Chul),이건호(Lee, Keon-Ho),장대희(Jang, Dae-Hee),최창호(Choi, Chang-Ho) 한국건축친환경설비학회 2015 한국건축친환경설비학회 논문집 Vol.9 No.5

The purpose of this study was to verify the suitability of the simulation test for domestic and international window-set U-values by discussing the input conditions and calculation methods for the same simulation test and comparing the calculated results for various window-sets. To this end, a total of 18 cases were selected, where glass, cavities, frames, spacers, windows sizes, etc, for double glazing fixed-windows and triple glazing fixed-windows have been changed. Then, domestic and international U-values by criteria were compared by performing a simulation using WINDOW&THERM, a certified program. The analytic results of domestic and international standards revealed that domestic standards and NFRC used the calculation method through the Edge area and that CEN used linear thermal transmittance(ψ) as a calculation method. In the Indoor and outdoor temperature conditions, domestic standards and CEN were similar but NFRC was somewhat different. The results of comparing U–value errors based on the Korea test found NFRC -6.22% ~+9.50%, CEN -4.98% ~ -1.23%. The U-value of the case calculated based on CEN standards tended to be mostly higher than that in domestic conditions. This tendency may have been caused by the difference between convective heat transfer coefficient and frame effective thermal conductivity in air space. The results of the domestic standards-applied simulation of window-set thermal transmittance showed an error rate within 10%, compared to NFRC and CEN. The above study confirmed the suitability of the simulation test for domestic window-set U-values.

일측 폐이식 성견에서 혈역학과 체액조절 호르몬의 상관관계

서강석,박창권,송대규,배재훈,박원균 啓明大學校 醫科大學 2002 계명의대학술지 Vol.21 No.1

폐이식에 의한 체액이나 혈압의 변동 및 신경의 절단은 혈압 및 체액의 조절에 관여하는 호르몬의 분비에 영향을 미치리라 생각되어 좌일측 폐이식 시 이식폐에 분포하는 신경이 절단된 상태에서 폐이식 후 수용견의 혈역학적 변동이 ANP 및 ADH의 분비와 어떠한 상관관계가 있는지를 관찰하였다. 한국산 성견 12마리를 대상으로 좌일측 폐이식을 시행하였다. 공여폐의 보존은 low potassium dextrane glucose용액을 이용하여 10℃에서 20시간동안 보존한 다음 수용견에 이식하였다. 수용견의 좌측 폐를 적출하기 전과 후, 그리고 이식 후 재관류 30분, 2시간 후에 각각 혈역학 및 동맥혈 가스분압을 측정하였고, 동맥혈에서 ANP 및 ADH의 농도를 측정하였다. 동맥혈의 P_(O_2) 및 P_(CO_2)는 유의한 변동은 없었다. 대퇴동맥압을 재관류 후 30분에는 유의하게 감소하였고, 재관류 2시간 후에는 다소 회복세를 보이는 경향이었으며, 맥압은 비교적 유지되었다. 폐동맥압은 좌측폐 절제 시 이완기 폐동맥압은 변동이 없는 반면에 수축기 폐동맥압은 증가하였고, 재관류 시 폐동맥압은 어느 정도 회복되는 양상이었다. 심박출량은 좌측 폐절제 후에는 감소하였으며 재관류후에도 낮게 유지되는 양상이었다. 반면에 심박수는 유의한 변화없이 유지되었다. 전신혈관저항 및 폐혈관저항은 좌측 폐절제 후나 재관류 30분에 증가하였으며, 재관류 2시간 후 폐혈관저항은 회복되는 양상이나 전신혈관저항은 회복되지 못하였다. 혈중 ANP는 일측 폐절제 후 증가하였고, 재관류 후에는 점차 회복되는 양상을 보였고, ADH는 일측 폐절제 후, 30분에 증가한 후 회복되는 양상을 보였다. 동맥혈 ANP의 변동은 동맥혈 P_(O_2)및 P_(CO_2)와 상관관계를 보였고, ADH는 전신 동맥압의 변동과 상관관계가 있었다. 이상의 결과로 좌일측 폐이식 시에도 ANP 및 ADH는 혈역학적 변화와 연관하여 동맥압 및 체액의 조절에 생리적으로 관여하는 것으로 사료되며, ANP의 분비는 동맥혈의 저산소증 그리고 ADH의 분비는 동맥의 압수용기를 통한 신경성 조절의 영향을 받을 수 있는 것으로 생각된다. The purpose of this investigation was to study changes of plasma atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) in Korean mongrel dogs after a left single lung transplantation and to evaluate the correlation between hemodynamic factors and secretory responses of ANP and ADH. Arterial P_(O_2 and P_(CO_2) did not change significantly. Femoral arterial pressure decreased after 30 min of reperfusion and recovered slightly at 120 min, whereas pulse pressure did not change. After pneumonectomy, systolic pulmonary arterial pressure increased, whereas diastolic pulmonary pressure remained unchanged. Althought cardiac output fell following pneumonectomy and reperfusion, heart rate was unchanged. The secretion of plasma ANP initially increased follwoing pneumonectomy, but subsequently recoverd. In each subject, ANP values showed stronger correlation with arterial P_(O_2) than other hemodynamic parameters. The secretion of plasma ADH also initially increased (p<0.05) after 30 min of reperfusion and thereafter recoverd, showing the strongest correlation with mean femoral arterial pressure. The present results suggest that the secretion of ANP and ADH seem to be well regulated in accordance with hemodynamic changes after a single lung transplantation. Hypoxia and systemic arterial pressure are the prominent factors in the secretion of ANP and ADH, respectively.

국내 중소하천의 유사량 산정 공식 적용에 관한 연구

강창훈 ( Chang-hoon Kang ),장석환 ( Suk-hwan Jang ),신철식 ( Cheol-sik Shin ),이현기 ( Hyeon-ki Lee ),김월봉 ( Wol-bong Kim ) 한국환경기술학회 2013 한국환경기술학회지 Vol.14 No.6

유사란 하천수에 의하여 운반되는 토사를 말하며 유수에 의해 침식, 퇴적이 반복되는 결과를 낳는다. 최근 기후변화와 함께 대규모 홍수가 빈번해 짐에 따라 하천의 유사량이 커지고 4대강 사업처럼 대규모 하천사업으로 인한 하상변동이 심해지고 있다. 하천에서 총유사량 추정은 하상변동의 원인이 되기도 하고 수자원 개발 및 관리를 위한 하천계획에 필요한 기본적 요소이다. 하지만 국내에서는 대규모 하천에서의 유사량은 측정을 실시하고 있지만 중소하천의 경우 유사량을 실측하여 산정할 수 있는 시간적 경제적 부담 때문에 측정할 수 있는 한계가 있다. 본 연구에서는 경기북부에 위치한 차탄천, 포천천, 경기남부에 위치한 남양천의 각 유량에 따른 부유사를 채취하여 시료분석을 통한 결과와 이론식을 적용하여 비교 분석 하였다. 채취한 시료는 입도분석을 실시하였으며 현장 측정 자료와 실내실험 결과를 토대로 수정 아인슈타인공식을 적용한 BORAMEP 프로그램을 사용하여 총유사량을 산정하였다. 분석 결과, 3m³/sec 이하 유량에서는 Yang 공식이 실측자료와 일치성을 나타냈고 3m³/sec 이상에서는 Shen and Hung 공식이 잘 나타났다. 각 이론을 적용하여 총유사량을 추정하고, 실측치를 이용하여 비교·검토함으로써 국내 중소하천에 적합한 산정 방법과 경기북부 지역 중소하천의 유량-총유사량 관계식을 제시하였다. Sediment transport means that the materials of bed and suspended load in the river are transported by flow tractive force, which causes scour and deposition. As the climate changes and dramatic flood occurs frequently, the sediment transport has increased and river bed changed. Sediment transport estimation is essential for the water resources management as well as river bed morphology. However, it is difficult to measure the total sediment in the middle and small river due to time and economic constrain. In this study, field data which were observed in 3 different river in Kyunggi-do were analyzed for comparing with empirical equations. Particle distribution analysis were carried out for the collected the suspended loads. The simulation model BORAMEP(Bureau of Reclamation Automated Modified Einstein Procedure) were used for the total sediment estimation along the field data analysis. As a result, Yang`s equation corresponds to field data under 3m³/sec and the equation of Shen and Hung corresponds to results over 3m³/sec. The results showed the way how sediment were estimated and discharge-total sediment relationship was determined by regression analysis in small and middle river of Kyunggi province region.

A Case of Occupational Hypersensitivity Pneumonitis Associated with Trichloroethylene

Jae, Young,Hwang, Eu Dong,Leem, Ah Young,Kang, Beo Deul,Chang, Soo Yun,Kim, Ho Keun,Park, In Kyu,Kim, Song Yee,Kim, Eun Young,Jung, Ji Ye,Kang, Young Ae,Park, Moo Suk,Kim, Young Sam,Kim, Se Kyu,Chang, The Korean Academy of Tuberculosis and Respiratory 2014 Tuberculosis and Respiratory Diseases Vol.76 No.2

Trichloroethylene (TCE) is a toxic chemical commonly used as a degreasing agent, and it is usually found in a colorless or blue liquid form. TCE has a sweet, chloroform-like odor, and this volatile chlorinated organic chemical can cause toxic hepatitis, neurophysiological disorders, skin disorders, and hypersensitivity syndromes. However, the hypersensitivity pneumonitis (HP) attributed to TCE has rarely been reported. We hereby describe a case of HP associated with TCE in a 29-year-old man who was employed as a lead welder at a computer repair center. He was installing the capacitors on computer chip boards and had been wiped down with TCE. He was admitted to our hospital with complaints of dry coughs, night sweats, and weight losses for the past two months. HP due to TCE exposure was being suspected due to his occupational history, and the results of a video-associated thoracoscopic biopsy confirmed the suspicions. Symptoms have resolved after the steroid pulse therapy and his occupational change. TCE should be taken into consideration as a potential trigger of HP. Early recognition and avoidance of the TCE exposure in the future is important for the treatment of TCE induced HP.

수산화칼슘수용액과 탄산가스의 반응에 의한 탄산칼슘 분말의 입도분석

강석호,정수창 嶺南大學校 工業技術硏究所 1989 연구보고 Vol.17 No.2

The effect of chemical reaction of carbon dioxide with aqueous calcium hydroxide on the particle size distribution of calcium carbonate products has been examined at reaction temperature range of 30°to 70℃, by varying reaction time from 25min to 70min. The particle size distributions of the reaction products obtained were compared by using 4 different instruments, i.e. image analyzer, Coulter counter, Microtrac and Elzone PSA. At 25min, of reaction time and 70℃ of reaction temperature the smallest average size of the precipitated CaCO₃could be achieved.

들깨잎의 揮發性 香氣成分에 關한 硏究

姜興順,林順英,南昌祐,尹錫權,邊時明 同德女子大學校 1995 同大論叢 Vol.25 No.1

To investigate the volatile flavor components of perilla leaves, analyses of kinds of cultivar by GC, GC/MS, UV, IR and NMR were carried out. The results obtained were summarized as follows : 1. The essential oils were extracted with diethyl ether after steam disillation. 2. The identified volatiles include 10 hydrocarbones, 6 alcohols, 3 aldehydes, 2 ketones and 1 miscellaneous components. 3. The major volatile component perilla ketone was identified by UV, IR and NMR spectrum. 4. The perilla ketone were identified in Suwon 8, 19, 21, 23, 24, 25, 26 and purpurea while perillaldehyde was identified in purpurea only.

유산양에서 발정동기화 유도와 인공수정 효율

장석민,강재구,최기명,김홍래,진동일 충남대학교 농업과학연구소 2007 농업과학연구 Vol.34 No.1

This study was conducted to evaluate the response of CIDR-S on estrus synchronization of dairy goats and the effect of artificial insemination on conception rate. Estrus synchronization of sexually matured Saanen goats was induced with insertion of CIDR-S into vagina for 15 days and injection of 500 IU PMSG before removal of CIDR-S. Artificial insemination was conducted using liquid or frozen semen by intra-cervical insemination with synchronized does. Estrus synchronization was 90% using CIDR-S insertion for 15 days. Conception rate of inseminated does was 20% - 25%, while that of natural mated does was 100%. These results suggested that synchronization of dairy goats can be successfully induced and artificial insemination method has to be improved for the practical use in dairy goats.

인위적 근피로 유발후 단축성과 신장성 근수축 운동시 근 토크의 변화

강영석,안창영,윤성원,나윤수 서울여자대학교 자연과학연구소 1995 자연과학연구논문집 Vol.6 No.-

The purpose of this study was to investigate the change of the peak torque, average power and total work of muscle function in the fatigue during eccentric(ECC) and concentric contraction (Con). Subjects were seven (7) adults man, who were paticipated in the ECC and CON experiments. Their gastronemus muscle were measured by CYBEX(Lurnax Co.) 6000system. Muscle fatigue was induced by 50 repetitionplantar flexion at 180 /sec load speed. In pre and post test, peak, average power and total work were analized when subjects were tested plantar flexion at 180/sec load speed. the summary of this results is as following : 1. Peak torque in the ECC were significantly higher than that of the CON. 2. Average power and total work of the Eccentric contraction appeared a higher than that of the Concentric contraction significantly. As a results. peak torque, average power and total workin the ECC was significantly higher than that of the CON throughout the experiments. In this fact, Mechanical efficiency in the ECC will expect to be higher than that of the CON.

디지털 FM이동통신에서의 검파후 최대비합성법의 구성

강석규,주창복 慶南大學校 附設 工業技術硏究所 1999 硏究論文集 Vol.17 No.-

본 논문에서는 검파후 최대비합성법에 의한 지연검파와 주파수검파의 경우에 대한 합성후의 SNR 관계식들을 관찰하고 이것들을 실현하는 실용적인 구성예를 보였다. 또한 이러한 구성에서 합성후 SNR의 열화특성과 이득특성 보이므로써 최대 SNR를 얻기위해 필요로 하는 가중계수의 변화를 얻기 위해 필요한 최대비합성에서의 검파기입력 SNR의 측정을 필요로 하지 않는 실용적인 검파후 최대비합성 수신검파기의 구성법이 합리적이라는 것을 보였다. This Paper observed the related formulas of SNR branched postdetection maximal ratio combining method in case of the delay detection and frequency detection and showed the practical configuration for the postdetection maximal ratio combining receiver. The defined SNR degradation characteristics after branches combining from the formulated results showed the practical postdetection maximal ratio combining structure is reasonable without the necessity measuring the input SNR of each branches to obtain the maximum SNR