지하수위 변화에 따른 지하공동 주변의 지하수 유동특성 해석

강재기(Jae Gi Kang),양형식(Hyung-Sik Yang),김경수(Kyung-Su Kim),김천수(Chun-Soo Kim) 한국암반공학회 2003 터널과지하공간 Vol.13 No.6

터널 분기부 암반 필러의 거동 연구

강재기(Jae-Gi Kang),이철규(Choul-Kyu Lee),이강일(Kang-Il Lee) 한국지반신소재학회 2015 한국지반신소재학회 논문집 Vol.14 No.2

본 연구에서는 터널을 대상으로 분기부 암반 필러의 거동을 3차원 수치해석 방법으로 검토하였다. 암반 필러의 거동에 영향을 미치는 매개변수로 암반 필러의 이격거리, 토피고, 암반등급 변화에 따른 안전율을 평가하였다. 터널 분기부 암반 필러의 이격거리가 증가할수록 토피고와 암반등급에 따른 안전율 변화 곡선은 비선형 거동을 보였으며, 터널 분기부에서 암반 필러의 거동 특성을 최소 안전율을 기준으로 안전율 도표로서 제안하였다. This study assessed the behavior of rock pillar in tunnel diverging area by using a three dimensional numerical analysis. Based on parameters affecting the behavior of rock pillar, this study evaluated different safety factors according to pillar width, depth and rock conditions. It turned out that as the rock pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in tunnel diverging area was suggested.

비전형적 리스버그인대와 비후된 전방십자인대의 충돌에 의한 탄발음 -1례 보고-

강재도,김형천,이기준,Kang, Jae Do,Kim, Hyung Chun,Lee, Gi Jun 대한관절경학회 1998 대한관절경학회지 Vol.2 No.2

저자들은 관절운동의 장애 없이 양측 슬관절의 탄발음과 동통 및 파행을 주소로 한 6세 소아에서 관절경을 통해, 일반적인 탄발음의 원인이 아닌 외측 원판형 연골의 비후된 근위부착형의 리스버그 인대와 전방십자인대의 확장된 기시부의 충돌에 의해 탄발음이 유발된 1례를 발견하고 이를 관절경적으로 절제함으로서 치료하여 좋은 결과를 얻었기에 문헌 고찰과 함께 보고하는 바이다. Discoid lateral menisci were common morphological anomaly and several classifications were proposed. Watanabe et al classified all discoid menisci, as seen arthroscopically, into three types 1) complete 2) incomplete and 3) Wrisberg ligament type. The purpose of this study is to report a rare case of both painful snapping knee joints in 6 year-old female. On arthroscopic examination, complete lateral discoid meniscus which consisted of taut Wrisberg ligament and intact tibial insertion of posterior horn was found, and abnormal anterior cruciate ligament(ACL) which has expanded femoral origin over the posterior articular surface of lateral femoral condyle was also found. At the time of arthroscopic surgery, hypertrophied high-riding Wrisberg ligament was resected, and expanded femoral origin of the anterior cruciate ligament was partially resected nearly to normal margin, and discoid lateral meniscus was saucerized. After these procedures, abnormal snapping sound was disappeared in full range of motion. On the follow-up examination after 1 year, pain and snapping sound were disappeared and any instability and limping were not found.

도로터널 분기부 암반 필라의 안정성 평가

강재기(Jae-Gi Kang),양형식(Hyung-Sik Yang),장선종(Sun-Jong Jang) 한국암반공학회 2014 터널과지하공간 Vol.24 No.5

본 연구에서는 도로터널 분기부 암반 필라의 거동을 3차원 수치해석 방법으로 검토하였다. 암반 필라의 거동에 영향을 미치는 매개변수로 암반 필라의 이격거리, 토피고, 암반등급 변화에 따른 안전율을 평가하였다. 필라의 이격거리가 증가할수록 토피고와 암반등급에 따른 안전율 변화 곡선은 비선형 거동을 보였으며, 도로터널 분기부에서 암반 필라의 거동 특성을 최소 안전율을 기준으로 안전율 도표로서 제안하였다. In this study, the behavior of rock pillar in the diverging area of road tunnel was assessed by using a three dimensional numerical analysis. Based on parameters affecting the behavior of rock pillar, different safety factors according to pillar width, depth and rock conditions were evaluated. It turned out that as the pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in the diverging area of road tunnel was suggested.

생슬러지의 초음파 조사에 의한 BNR공정의 탄소원 타당성 연구

황규대 ( Hwang Gyu Dae ),강재순 ( Kang Jae Sun ),장준기 ( Jang Jun Gi ) 한국물환경학회 2003 한국물환경학회지 Vol.19 No.5

In the sonochemical reaction, the solid of sludge can be disintegrated and solubilized by hydromechanical shear force, pyrolysis, and free radical attack during the cavitation. This study was performed to evaluate the feasibility of ultrasonically treated raw sludge as carbon source for biological denitrification and phosphate release. A 530W ultrasonic processor with a frequency of 40kHz was used to sonicated the raw sludge from wastewater plant. To find the optimal SCODcr buildup condition. we examined the effects of solid concentration of sludge, ultrasonic density, irradiation time, aeration, and pH on TSS and SCODcr concentration during the ultrasonic irradiation on raw sludge. Ultrasonic irradiation was applied to raw sludges with different solid contents (1, 3, and 5%.) and different ultrasonic density (0.04, 0.06, and 0.12W/rnl). Ultrasonic irradiation showed a rapid and significant decrease in TSS concentration in raw sludge. The kinetic of the degradation rates of TSS by ultrasonic irradiation was satisfactorily described by a pseudo-first order reaction. The degradation efficiency of solid in raw sludges were over 60%, and ranged from 3.0 to 7.2 ㎎TSS/W . hr. Also the SCODcr yields of 2.1 -3.2 ㎎SCODcr/W·hr in this study were observed and depended strongly on ultrasonic density. With aeration. the sonication on raw sludge further increased SCODcr concentration. However, it is less effective to irradiate ultrasonically the pH-adiusted raw sludge. The optimal operating condition to increase soluble organics was to sonicate the sludge with 5% TSS under the ultrasonic density of 0.12W/ml and showed the yield of 3.2 ㎎SCODcr/W . hr. Also the sonicated sludges with different sonication time(ranging between 0-9hrs) under 0.I2W/ml were fed into the batch reactors as carbon source. Those ones had a strong influence on the denitrification rate and the P-release concentration. The specific denitrification rates of batch reactors varied within a range from 0.46 to 1.97 mgNO₃-N/gVSS·hr, and 1.33-1.85 gSCODCr consumed/gNO₃-N removed was observed. The concentration of phosphate which was released by poly P microbes were in the range of 0-4.75㎎/L. and 0.55-1.22gPO₄-P released /gSCODcr consumed was showed. The economically most competitive sludge as carbon source was one under 3hr sonication time to accomplish the high denitrification rate and the P-release concentration. Therefore, the ultrasonically treated sludge can be another carbon source for BNR process.

분말활성탄이 투여된 MBR 공정을 이용한 축산폐수 잔류유기물 제거

황규대(Gye Dae Whang),강재순(Jae Soon Kang),장준기(Jun Gi Jang) 大韓環境工學會 2002 대한환경공학회지 Vol.24 No.1

플러그인 HEV용 변속기전달오차와 하중분포에 관한 연구

장기(Qi Zhang),강재화(Jae-Hwa Kang),윤기백(Gi-Baek Yun),류성기(Sung-Ki Lyu) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.3

In recent years, world is faced with a transportation energy dilemma, and the transportation is dependent on a single fuel - petroleum. However, Hybrid Electric Vehicle(HEV) technology holds more advantages to reduce the demand for petroleum in the transportation by efficiency improvements of petroleum consumption. Therefore, there is a trend that lower gear noise levels are demanded in HEV for drivers to avoid annoyance and fatigue during operation. And meshing transmission error(T.E.) is the excitation that leads to the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. This paper presents a method for the analysis of gear tooth profile and lead modification, and the predictions of transmission error and load distribution are shown under one loaded torque for the 1<SUP>st</SUP> gear pair of HEV gearbox. The test is also obtained before tooth micro-modification under the torque. At last, the appropriate tooth modification is used to minimize the transmission error and load distribution under the loaded torque. It is a good approach which the simulated result is used to improve the design in order to minimize the radiation gear whine noise.

Analytical Prediction of Bearing Life and Load Distribution for Plugin HEV

장기(Qi Zhang),강재화(Jae-Hwa Kang),윤기백(Gi-Baek Yun),류성기(Sung-Ki Lyu) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.5

The transportation is almost dependent on a single fuel petroleum with transportation energy dilemma. Hybrid Electric Vehicle(HEV) technology holds more advantages on efficiency improvements for petroleum consumption at the transportation. And bearing is recognized as the important component of gearbox. Gearboxes for HEV transmission have been ensured the highest reliability over some years in withstanding high dynamic loads. At the same time, the demands of lightweight design and cost minimization are required by thought-out design, high-quality material, superior production quality and maintenance. In order to design a reliable and lightweight gearbox, it is necessary to analyze bearing rating life methods between standard and different bearing companies with calculation methods for modification factors. In this paper, the influence of life time of bearings will be pointed out. Bearing contact stress and load stress distribution of HEV gearbox are obtained and compared with Romaxdesigner and BearinX. And the unequal wear of the left bearing for the gearbox intermediate shaft is investigated between simulation and test.

Mohr-Coulomb 파괴접근도 방법을 이용한 비대칭 분기부 암반필러의 안정성 평가

이철규(Choul-Kyu Lee),이강일(Kang-Il Lee),강재기(Jae-Gi Kang) 한국지반신소재학회 2016 한국지반신소재학회 논문집 Vol.15 No.4

본 연구에서는 터널을 대상으로 비대칭 분기부 암반 필러의 거동을 3차원 수치해석 방법으로 검토하였다. 터널 비대칭 분기부의 경우 필러부의 안정성을 확보하는 것이 본 터널의 안정성을 좌우하는 매우 중요한 요소라 할 수 있다. 암반 필러의 거동에 영향을 미치는 매개변수로 암반 필러의 이격거리, 토피고, 암반등급 변화에 따른 안전율을 평가하였다. 터널 비대칭 분기부 암반 필러의 이격거리가 증가할수록 토피고와 암반등급에 따른 안전율 변화 곡선은 비선형 거동을 보였으며, 터널 비대칭 분기부에서 암반 필러의 거동 특성을 최소 안전율을 기준으로 안전율 도표로서 제안하였다. This study assessed the behavior of rock pillar in tunnel asymmetric diverging area by using a three dimensional numerical analysis. The stability of pillar is very important for the ensure the stability of the tunnel asymmetric diverging area. Based on parameters affecting the behavior of rock pillar, this study evaluated different safety factors according to pillar width, depth and rock conditions. It turned out that as the rock pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in tunnel asymmetric diverging area was suggested.

Glycol Ether를 이용한 국내산 참나무류의 LAS 펄프화

김강재(Kang-Jae Kim),나기백(Gi-Baek Nah),류지애(Ji-Ae Ryu),엄태진(Tae-Jin Eom) 한국펄프·종이공학회 2018 펄프.종이技術 Vol.50 No.2

The pulp from Korean mixed oaks were prepared by LAS (Low temperature, Atmospheric pressure, and Short reaction time) pulping method with different temperature and reaction. The pulp prepared under low cooking temperature had a high residual lignin content spite of increasing cooking time. However, as the cooking temperature increased, the lignin in the wood was easily removed and the yield of pulp increased and the residual lignin content decreased. The peak intensities derived from hemicellulose and lignin, which have been confirmed from wood chips, are gradually weaker in response to pulping. Peak regions representing cellulose were strongly confirmed from IR data of pulp prepared at more than 110℃. It can be concluded that pulping of Korean mixed oak was suitable for 60 minutes at 110℃. It was predicted that the possibility of using the LAS pulp as a raw material for papermaking was high because the LAS pulp showed the same fiber characteristics as KP. LAS pulp showed higher glucose content than wood chip, many hemicellulose was eluted by acid catalyst and showed low xylose content. The reason why the syringaldehyde ratio of LAS pulp decreased compared to wood chips was that a large amount of lignin was condensed by cooking reaction.