디지털 카메라를 이용한 3차원 피해물량 추정 기법 개발

조재웅,최우정,김기홍,심재현,최성열,Cho. Jae-Woong,Choi. Woo-Jung,Kim. Gi-Hong,Shim. Jae-Hyun,Choi. Sung-Yeul 한국방재학회 2011 한국방재학회논문집 Vol.11 No.6

최근 집중호우 및 태풍과 같은 자연재해가 증가하면서 이로 인한 인명, 재산 피해가 크게 증가하고 있다. 그러나 복구를 위한 피해물량 산정이 대부분 수작업으로 이루어지고 있어 조사자의 주관이 포함되고, 이로 인하여 정확한 피해조사가 어려운 실정이다. 특히 길이, 면적이 아닌 토량과 같은 3차원 피해물량을 계산하는 경우에는 조사자에 따라 차이가 많이 발생하며, 피해물량이 과대산출되는 경우가 많다. 따라서, 본 연구에서는 피해 후 스테레오 영상만을 이용하여 피해전의 가상단면을 구현하고, 차이 값을 활용하여 토량을 계산할 수 있는 3차원 피해물량 추정 기법을 개발하였다. 지상영상기반 현장조사 시스템에 적용하여 정확도를 검증한 결과 6.4%이내의 오차가 발생하는 것으로 나타났다. Recently, as natural disasters like torrential rains and typhoons increase, loss of life and property damage have multiplied. But estimated damage amount for restoration is apt to be influenced by investigator`s subjective judgment because it is still manually calculated in the majority of cases. This makes accurate investigation for damage assessment difficult. Especially in 3D damage assessment, such as soil volume, the results vary widely with the investigators. In many cases, the damages are over estimated. We developed an estimating technique for 3D damage amount, which creates pre-disaster virtual surface using only post-disaster stereo images, and calculates the soil volume from the difference between pre-disaster virtual surface and post-disaster surface. The accuracy of developed technique was verified through Field Investigation System. The error was less than 6.4%.

급경사 자갈하상 만곡수로의 최대세굴심 산정공식 평가

조재웅,남아름,우태영,박상덕,Cho, Jaewoong,Nam, A-Reum,Woo, Tae Young,Park, Sang Deog 한국수자원학회 2016 한국수자원학회논문집 Vol.49 No.6

본 연구는 급경사 자갈하상 만곡수로의 이동상 수리실험을 이용하여 만곡부 최대세굴심 산정공식들의 적용성을 평가하였다. 평균입경 43mm의 하천자갈을 $90^{\circ}$ 만곡 급경사 개수로에 포설하고 유량과 하상경사에 따른 만곡부의 최대세굴심을 조사하고 세굴심 공식으로 산정한 최대세굴심과 비교하였다. 자갈하상 만곡부 국부세굴은 유입부의 하상경사 0.02이상 $F_r$ 0.95이상에서 발생하였다. 이 수로에서 Lacey공식과 Zeller공식을 제외한 기존 세굴심 산정공식들은 최대세굴심을 과대 추정하는 것으로 나타났다. 하상재료를 고려한 Lacey공식과 접근경사와 만곡도를 반영한 Zeller공식은 급경사 자갈하상 만곡부의 최대세굴심 평가에 적용될 수 있는 것으로 판단된다. The existing methods to estimate the maximum scour depth in the bend of steep gravel bed channel have been evaluated by the hydraulic movable-bed experiments. In the $90^{\circ}$ bend steep-slope channel paved with the fluvial gravels which are uniform in size and have a mean diameter of 43mm, the maximum scour depths due to the flow discharge and the gradient of bed slope have been investigated and compared with the scour depth computed from the equations. The local scour has occurred in conditions that the bed slope is steeper than 0.02 and the $F_r$ is greater than 0.95. Except Lacey's equation and Zeller's equation, the existing methods computing the maximum scour depth overestimate the maximum scour depth in the steep channel with the very coarse gravel bed. However, Lacey's equation with the bed material size and Zeller's equation considering the approach channel gradient and the bend angle may be relatively used to estimate the scour depth in bend of the steep gravel-bed river.

차동 기어 장치에 관한 구조 해석

조재웅,한문식,Cho, Jae-Ung,Han, Moon-Sik 한국생산제조학회 2009 한국생산제조학회지 Vol.25 No.4

This study investigates the stress at gear by modelling differential gear and using FEM. When gear is driven under power, high equivalent stress of 1596.2MPa is occurred at the stationary shaft. Maximum equivalent stress of 1596.2MPa is also occurred at the bottom and root of tooth and its fatigue life becomes 12.4 as the shortest cycle. As much as it becomes away from the center of gear, the maximum deformation becomes occurred. As exact power is delivered with the precise design of gear, the loss of power energy can be decreased.

스마트폰의 Gyro 센서를 이용한 피해규모 측정방안

조재웅,최우정,Cho. Jaewoong,Choi. Woojung 한국방재학회 2014 한국방재학회논문집 Vol.14 No.4

우리나라의 피해조사체계는 피해발생 후 7일이내에 조사를 완료해야 하므로 신속하고 정확한 피해조사가 요구된다. 그러나 시간 및 인력 부족으로 인하여 정확한 피해조사가 이루어지지 못하고 있는 실정이며, 특히 피해규모 산출시 목측 등으로 인한 대략적인 피해규모 조사가 이루어지고 있어 객관적이고 정량적인 피해규모 산출 방법이 필요하다. 이에 국립재난안전연구원에서는 정량적인 피해규모 조사를 위하여 2009년 `지상영상기반 현장조사 시스템`을 개발한바 있으며, 신속한 피해조사를 위하여 2011년부터 2013년까지 `스마트폰 기반 피해조사 시스템`을 개발한바 있다. 그러나 이 두 시스템은 각각 정량적인 피해조사는 가능하지만 현장휴대성과 신속한 조사부분에서 효율성이 부족한 것으로 나타났으며, 스마트폰 기반 피해조사 시스템은 휴대성이 좋고 신속한 피해조사는 가능하지만 정량적인 피해규모조사 부분에서 효율성이 부족한 것으로 나타났다. 따라서 본 연구에서는 휴대성이 좋고 신속한 피해조사가 가능한 스마트폰 피해조사 시스템에 정량적이고 객관적인 피해규모 산출을 위하여 스마트폰의 자이로 센서를 활용하여 대상물까지의 거리 및 대상물의 규모를 측정할 수 있는 방법에 대하여 제시하였다. In Korea, disaster investigation needs rapid and accurate because we must finish that during 7 days. But estimated damage amount for restoration is apt to be influenced by investigator`s subjective judgment because it is still manually calculated in the majority of cases. This makes accurate investigation for damage assessment difficult. Accordingly, National Disaster Management Institute has developed `Field Investigation System using Stereo Images` for quantitative measurement of disaster damage in 2009. And also, they has developed `Disaster Damage Investigation System using Smartphones` for prompt disaster damage investigation from 2011 to 2013. However, this two systems have different pros and cons. The Field Investigation System using Stereo Images is possible to be quantitative measurement of disaster damage, but the system is impossible to be prompt disaster damage investigation. On the contrary to this, another system that is using Smartphones is possible to be prompt disaster damage investigation, but the system is impossible to be quantitative measurement of disaster damage. In this study, suggest method on measurement of the damage scale using gyroscope in smartphone.

자동차 로우어 암의 내구성 및 응력 해석

조재웅,한문식,Cho, Jae-Ung,Han, Moon-Sik 한국생산제조학회 2010 한국생산제조학회지 Vol.10 No.6

The capability of automotive suspension system depends on steering safety of knuckle and lower control arm. In this study, light weight is applied with lower arm by the material of aluminium alloy. Distributed stress, fatigue life and proper vibration are analyzed with multiple loads happened by automobile. The durability of lower arm can be verified by the result of structural analysis.

자동차 현가장치의 구조 강도 해석

조재웅,권오범,한문식,Cho, Jae-Ung,Kwon, Oh-Beom,Han, Moon-Sik 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.3

This paper describes the analysis of state when load applies to McPherson strut assembly. Strut assembly except knuckle-arm are created with 3 dimensional modeling program. Stress and structural strength on this model are analyzed by analysis program as load applies on the lower part of assembly modeling. When McPherson suspension is applied with 3000N at Z direction, maximum stress at spring becomes 433MPa and the cycle of minimum life is 4321. The designed modeling suspension at this study has no possibility with resonance.

디스크 브레이크의 구조 및 열 해석

조재웅,한문식,Cho, Jae-Uug,Han, Moon-Sik 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.2

Continuous contraction and expansion of disk brake can be due to friction and temperature difference at repeated sudden braking. As serious vibration at disk is produced, the braking force will be changed ununiformly and braking system can not be stabilized. Temperature and heat flux at disk brake are investigated by structural and thermal analysis in this study. The maximum equivalent stress and displacement are shown respectively at the ventilated hole and the lower part of disk plate. At thermal analysis of initial state, temperature on disk plate is distributed from $95.9^{\circ}C$ to $100^{\circ}C$. The maximum heat flux of $0.0168W/mm^2$ is shown at the inner friction part between disk plate and pad. At thermal analysis of transient state, temperature on disk plate is distributed from $95^{\circ}C$ to $96.5^{\circ}C$ after 100 second. The maximum heat flux of $0.0024W/mm^2$ is also shown at the inner friction part between disk plate and pad. By comparing with initial state, the temperature on disk plate is more uniformly distributed and heat flux is more decreased by 7 times at transient state.

차체의 충돌에 관한 시뮬레이션 해석

조재웅,민병상,한문식,Cho, Jae-Ung,Min, Byoung-Sang,Han, Moon-Sik 한국생산제조학회 2009 한국생산제조학회지 Vol.25 No.1

This study analyzes the result with dynamic simulation about deformation according to time when a car impacts bollard. These results are shown as followings. The maximum deformation is shown at the lower part of front grass in case of the impact of front or passenger seat but this deformation is shown at the lower part of rear bumper in case of double impact. The maximum equivalent stress is shown at the upper part by the side grass of driver seat at the elapsed time of 0.00075 second after impact in case of the impact of front or passenger seat but this deformation is shown at the front bonnet at the elapsed time of 0.004 second after the additional impact in case of double impact. The maximum total deformation or equivalent stress is shown nearly same in case of the impact of front or passenger seat. But the value of this deformation or equivalent stress in case of the impact of front or passenger seat is shown with 2 times or more than 17% respectively as this value in case of double impact.

불규칙 하중을 받는 휠에서의 피로 파손 해석

조재웅,한문식,Cho, Jae-Ung,Han, Moon-Sik 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.1

The variable fatigue load is simulated in this study. The stability and the life of the material are analyzed theoretically by Ansys program. These results are successfully applied to the practical wheel to predict the prevention of fracture and the endurance. The life and the damage on the every part of the fatigue specimen can be predicted. As the available lives are compared for every loading variation, the rain flow and damage matrix results can be helpful in determining the effects of small stress cycles in any loading history. The rainbow and damage matrices illustrate the possible effects of infinite life. The safety and stability of wheel and the other practical structures according to the variable load can be estimated by using the results of this study.

엔진 부품에 대한 피로 및 전동해석

조재웅,한문식,Cho, Jae-Ung,Han, Moon-Sik 한국생산제조학회 2010 한국생산제조학회지 Vol.10 No.6

This study analyzes the results with the simulation of heat transfer, structural stress, fatigue and vibration on main parts of engine. The maximum temperature is shown by $300.73^{\circ}C$ on the upper part of piston with the heat transfer. Maximum total deformation or equivalent stress is shown by 65.31mm or 21364MPa respectively at the upper plane of piston with the structural analysis inclusive of heat transfer. The minimum life is shown by the cycle less than $10^7$ at the part of crankshaft with the fatigue analysis. The frequency with the maximum amplitude of deformation is shown by 14Hz. Maximum total deformation or equivalent stress is shown respectively by 93.99mm on the upper plane of piston or 42625MPa at the part connected with crack shaft and connecting rod at 14Hz. The durability of engine design can be verified by using the analysed result of this study.