황토모르타르의 압축강도 증진을 위한 실험적 연구

황원주 ( Hwang Won Ju ),김종우 ( Kim Jong Woo ),하상수 ( Ha Sang Su ) 한국구조물진단유지관리공학회 2018 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.22 No.2

The purpose of this experimental study is to increase the strength of mortar mixed with activated Hwang-Toh (AHT) and granulated blast furnace slag (GGBS) as a compound for the development of eco-friendly concrete. The compressive strength test was carried out by making mortar specimens with a certain ratio of AHT and GGBS. The percentage of AHT were at 30% and 50% and the GGBS were a 40% and 50% as Major variables. The results of this study showed that for specimens with percentage of AHT at 30% with GGBS increased above the strength of the mortar without the binding. However, the compressive strength of experimentation with percentage of AHT at 50% with partially replace GGBS has decreased by more than the mortar without the binding. Therefore, further study is deemed necessary.

인버터 구동용 유도전동기 고정자 권선의 절연특성 연구

황돈하,김동희,이광식,정원영,김영훈,오승훈 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.2

Inverters with high speed switching and advanced PWM techniques are widely used for variable speed applications. But some adverse effects on the stator winding insulation are reported due to excessive voltage stress, which results in the premature insulation breakdown. This is aggravated by the high switching speed of modem switching devices such as IGBT (Insulated Gate Bi-polar Transistor) with which the rate of rise in voltage (dv/dt) increases considerably. In this paper, the test results for evaluation on the stator winding insulation of 310V induction motors are presented. Also, the insulation characteristics are presented in order to analyze the insulation strength under high voltage due to high switching speed of IGBT PWM inverter. 26 induction motors of 6 types with different wires and insulation techniques are built and thoroughly tested. The maximum partial discharge (PD) magnitude (Qm) and the discharge inception voltage (DIV) are obtained by PD test. Under AC current test, the rate of change in AC current (ΔI) and the change in dissipation factor (Δtanδ) are measured. From the above test data, the effects due to different wires and insulation techniques on the insulation characteristics of low-voltage induction motors are compared and analyzed. The insulation technique to enhance the insulation strength is suggested from the test results.

고속전철 추진 시스템의 미끄럼 방지 제어기법에 관한 연구

황돈하,김동희,노채균,심광열,조규판,정원영 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.2

Induction motor drive with PWM inverter control has been developed for Korean High Speed Railways. To improve traction performance, the anti-slip control(ASC) to recover adhesion must be considered. This paper describes a novel hybrid anti-slip control method for the induction motor drive. By introducing the vector control for drive system, quick response of the motor torque can be achieved when wheels are going to slip. A hybrid control scheme by mixing two conventional control methods (slip velocity feedback control and slip detection pattern control) for wheel slip and re-adhesion is proposed. This control method is simulated by motor drive, train load, and friction-creep models. The train running simulation results based on induction motor vector control with PWM inverter show that good re-adhesion characteristics are obtained.

레진시멘트의 색안정성에 대한 가속시험

송하정,박수정,황윤찬,오원만,황인남 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.4

본 연구는 레진 시멘트의 색 안정성을 평가하여, 레진 시멘트의 변색에 의한 심미 수복물의 실패의 가능성을 평가하고자 시행하였다. 4종의 이원중합형 레진 시멘트인 Panavia-F (PA; KURARAY), Duolink (DL; BISCO), Variolink II (VL; Ivoclar Vivadent),및 RelyX Unicem (UC; 3M ESPE)과 1종의 자가중합형 레진 시멘트인 Resiment Ready-Mix (with fluoride) CE (RM: j.l.Blosser)를 사용하였으며 , 대조군으로 복합레진 Gradia Direct (GD; GC)과 복합 레진 인레이용 Tecera Dentin A3 (TE; Bisco)를 사용했다. 각 재료 당 직경 6.5 ㎜, 두께 4.5 ㎜의 디스크형 시편 10개를 제작하였다. 중합 후 시편은 분광색채계측기인 Spectrolino (GretagMacbeth)를 이용해 CIE L^(*)a^(*)b^(*)값을 측정하고 가속시험을 위해 빛이 차단된 refrigerated bath circulator에서 60 ℃ 증류수에 30일간 보관 후에 색 측정을 시행하고, 시험 전 후의 색차를 계산하였다. 가속 시험 후 L^(*) 값은 감소하는 앙상을 보였고, a^(*) 값은 증가하는 양상을 보였지만 유의한 차이는 없었다. 반면 b^(*) 값은 유의하게 증가하였다 (p<0.05). TE가 15일과 30일 모두에서 가장 적은 색변화 (p < 0.05)를 보인 반면 GD는 15일 가속 실험 후 큰 색변화를 보였다. 30일 가속 실험 후 PA, VL, RM, DL 그리고 UC 순으로 ΔE^(*)값이 커졌으며 (p < 0.05), 30일 후 모든 레진시멘트들은 육안으로 변색을 인지할 수 있는 3 이상의 ΔE^(*) 값을 보였다. The purpose of this study was to evaluate the color stability of resin cements with accelerated test. Four dual curing resin cements: Panavia-F (KURARAY), Duolink (BISCO), Variolink-II (Ivoclar Vivadent), and RelyX Unicem (3M ESPE) and 1 self curing resin cement: Resiment CE (j. 1. Blosser) were used in this study. In control group, Gradia Anterior (GC) composite resin and Tescera Dentin (Bisco) indirect composite were used. Ten disk shape specimens were made from each resin cement. The specimens were subjected to an accelerated aging process in a refrigerated bath circulator at 60 ℃ for 15 and 30 days. Spectrophotometric analyses were made before and after 15 days and 30 days of accelerated aging time. The color characteristics (L^(*), a^(*), b^(*)) and the color difference (ΔE^(*)) of the specimens before and after immersion were measured and computed. Regardless of type of the resin cements, L^(*) value was decreased and a^(*) value was increased, but there were no significant difference. But b^(*) value was increased significantly (p < 0.05). Tescera inlay showed least color change (p < 0.05), but Gradia showed notable color change after 15 days. After 30 days on accelerated aging, ΔE^(*) value was increased (Panavia-F < Variolink-II < Resiment CE < Duolink < Unicem) (p < 0.05), but there were no significant difference among Panavia-F, Variolink-II, and Resiment CE groups. After 30 days of accelerated aging, ΔE^(*) value of all resin cements were greater than 3.0 and could be perceived by the human eye.

탄소 나노튜브의 길이변화에 따른 물리적 특성에 관한 이론적 연구

문원하,변기량,황호정 중앙대학교 기술과학연구소 2001 기술과학연구소 논문집 Vol.31 No.-

본 연구에서는 나노 단위의 소자개발을 위하여 (6, 6) 탄소 나노튜브의 유한길이에 따른 물리적 특성에 관해 알아보았다. 먼저 브레너 전위식을 이용하여 모자가 씌워진 탄소 나노튜브의 최적화된 구조를 얻어내었다. 그후 탄소 나노튜브의 최적화된 구조를 가지고 TBMD 시뮬레이션을 수행하였다. TBMD 결과, 에너지 밴드갭은 길이에 따라 반비례하는 것을 알 수 있으며 특히 길이가 20 이하인 경우 탄소와 탄소간의 나타나는 π 결합의 영향으로 인하여 길이에 따라 에너지 밴드갭이 민감한 변화를 보이며 진동함을 알 수 있다. 여기서 (6, 6) 탄소 나노튜브의 에너지 배드갭은 0.3∼2.5 eV 정도임을 알 수 있다. The electronic properties of Carbon Nanotube(CNT) are currently the focus of considerable interest. In this paper, the electronic properties of finite length effect in CNT for carbon nano-scale device is presented. To Calculate the electronic properties of CNT, Empirical potential method (the extended Brenner potential for C-Si-H) for carbon and Tight Binding molecular dynamic (TBMD) simulation are used. As a result of study, we have known that the value of the band gap decreases with increasing the length of the tube. The energy band gap of (6,6) armchair CNT have the ranges between 0.3 eV and 2.5 eV. Also, our result are in agreements with the result of the other computational techniques.

새로운 세파로스포린 유도체의 합성과 항균력에 관한 연구

박의석,김하정,최원식,황선암 순천향대학교 기초과학연구소 1996 순천향자연과학연구 논문집 Vol.2 No.1

New cephalosporin antibiotics, 7-[(3,4-dihydro-6-methoxycarbonyl-2,2-dimethyl-2H-1,4-thiazin-3-yl 1-oxide) -acetamido]-3-heterocyclothiomethyl-3-cephem-4-carboxylic acid derivatives (2a-2d) were synthesized. Anti-bacterial activities of these new cephalosporin derivatives and the relationship between their stucture and their activities were examined. Among them, 7-[3,4-dihydro-6-methoxycarbonyl-2,2-dimethyl-2H-1,4- thiazin-3-yl1-oxide)acetamido]-3-[(2-methyl-1,3,4-thiadiazol-5-yl)thiomethyl]-3-cephem-4-carboxylic acid exhibited the broad antibacterial activities against Gram(+) and Gram(-) bacteria.

직접 분사식 가솔린 엔진의 분사 조건 변화에 따른 실린더 내 분무 유동 특성에 관한 연구

전문수,장광진,황용하,최원호 忠州大學校 2005 한국교통대학교 논문집 Vol.40 No.2

This study presents the spray characteristics of high pressure swirl type gasoline injector for the application of direct-injection gasoline engine. For the purpose, Mie seattering technique and the PDPA(Phase Doppler Particle Analyzer) measurements were used for the fundamental spray characteristics, In-cylinder spray flow motion was also visualized in order to optimize combustion system of the engine. Various fuel injection conditions such as intake flow condition, different combustion chamber shape, fuel injection timing, and engine speed were considered to obtain the detailed in-cylinder spray characteristics by use of ICCD(Intensified Charge Coupled Device) camera through the single-cylinder potical engine. From the experimental results, the test injector shows a good low-end linearity between the dynamic flow and fuel injection pulse width and the fuel spray of 20mm or less in SMD(Sauter Mean Diameter) with good spray symmetry. In addition, the in-cylinder tumble flow has more effect on the homogeneous mixture formation than that of in-cylinder swirl flow at early injection mode and the in-cylinder swirl flow plays a better role of stratified mixture preparation than tumble flow at late injection mode.

석고를 치환한 황토모르타르의 압축강도 특성

김종우 ( Kim Jong Woo ),황원주 ( Hwang Won Ju ),하상수 ( Ha Sang Soo ) 한국구조물진단유지관리공학회 2018 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.22 No.2

The purpose of this study is to compare the compression strength of gypsum substituted mortar with that of mortar. After replacing the cement with the loess, a portion of the remaining cement was replaced with gypsum to make specimens. When the gypsum is replaced, the strength of all the specimens is lower than that of the standard specimen. It is necessary to use a long-term strength mixed material to replace this.

Right hepatic vein stenosis at anastomosis in patients after living donor liver transplantation: optimal Doppler US venous pulsatility index and CT criteria--receiver operating characteristic analysis.

Hwang, Hye Jeon,Kim, Kyoung Won,Jeong, Woo Kyoung,Song, Gi-Won,Ko, Gi-Young,Sung, Kyu Bo,Shin, Yong Moon,Kim, Pyo Nyun,Ha, Tae-Yong,Moon, Deok-Bog,Kim, Ki-Hun,Ahn, Chul-Soo,Hwang, Shin,Lee, Sung-Gyu Radiological Society of North America 2009 Radiology Vol.253 No.2

<P>PURPOSE: To establish optimal Doppler ultrasonographic (US) venous pulsatility index and computed tomographic (CT) criteria for right hepatic vein (RHV) stenosis after living donor liver transplantation (LDLT) and to compare accuracies of these methods by using receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: This retrospective study was approved by an institutional review board; informed consent was waived. Eighty patients (48 men, 32 women; mean age, 51.5 years +/- 9.2 [standard deviation]) underwent Doppler US and CT within 8 days of hepatic venography following right lobe LDLT between October 2006 and September 2008. At venography, RHVs were classified into a stenosis or nonstenosis group. At Doppler US, venous pulsatility index was defined as the difference between maximum and minimum frequency shifts divided by maximum frequency shift. At CT, diameters of anastomosis and RHV were measured; percentage of stenosis was calculated. Mean Doppler US and CT parameters in the two groups were compared; ROC analysis was performed. RESULTS: There were 30 stenotic and 50 nonstenotic RHVs. Mean venous pulsatility index and mean anastomosis diameter were significantly lower and mean percentage of stenosis was significantly higher in the stenosis than the nonstenosis group (P < .001 each). Optimal cutoffs for venous pulsatility index, anastomosis diameter, and percentage of stenosis were 0.16, 3.7 mm, and 47%, respectively. Sensitivity and specificity were 86.7% and 68.0% for venous pulsatility index, 96.7% and 88.0% for anastomosis diameter, and 96.7% and 86.0% for percentage of stenosis, respectively. At ROC analysis, anastomosis diameter (P = .002) and percentage of stenosis (P = .003) were significantly more accurate than venous pulsatility index. CONCLUSION: CT is more accurate than Doppler US for RHV stenosis after LDLT, with venous pulsatility index as the sole sonographic criterion. Patients suspected of having RHV stenosis at Doppler US may benefit from CT to reduce unnecessary venography.</P>

S-538 : Two cases of right middle lobe syndrome due to eosinophilic mucus in adults

( Ha Won Hwang ),( Joo Hee Kim ),( Sung Hoon Park ),( Yong Il Hwang ),( Seung Hun Jang ),( Ki Suck Jung ),( In Jae Lee ),( Dong Hoon Kim ) 대한내과학회 2013 대한내과학회 추계학술대회 Vol.2013 No.1

Right middle lobe syndrome (RMLS) is defined as a recurrent or chronic collapse of the middle lobe of the right lung by certain pathologic conditions. RMLS is a relatively uncommon condition having multiple etiologies and various clinical presentations. Here, we report two cases of RMLS due to the eosinophilic mucus. The first case was a 57-year old female visited our clinic because of non productive cough for 3 weeks developing after upper respiratory tract infection. A chest X-ray showed a persistent consolidation in the right middle lobe despite of treatment with antibiotics over two weeks. The second case was a 52-year old female transferred to our clinic for the treatment of pneumonia. Her respiratory symptoms and radiologic abnormalities were gradually resolved after the administration of antibiotics but still remained RML infiltration on the x-ray. In both cases, chest CT scans showed RML obstruction and bronchoscopic findings were the RML bronchus obstruction by thick and yellowish materials. Pathologic findings showed mucus with many eosinophils and Charcot-Leyden crystals. They had no history of bronchial asthma. Pulmonary function tests were normal as well as negative bronchodilator responses. They showed negative responses to fungal allergens such as Alternaria, Aspergillus, Cladosporium, and Penicillium in both skin tests and specific IgE antibodies using ImmunoCAP. However, they had eosinophilia in blood and bronchoalveolar larvage fluid and elevated total IgE levels. Once the mucus plugs removed, their symptoms and x-ray were normalized. In conclusion, eosinophilic mucus should be considered as one of the causes in patients with RMLS regardless of typical asthmatic symptoms.