초록 ▼

연구결과
필요성 및 목표
○ 현재 혈흔형태분석에서 충격비산혈흔의 발혈부위 추정방법은 직선궤도법에 기초한 기법 및 이를 구현하는 소프트웨어만이 존재하나, 실제 혈액방울은 중력과 공기저항의 영향으로 포물선 운동을 함
○ 따라서 곡선궤도를 반영한 발혈부위 계산공식 및 소프트웨어의 개발이 필요
방 법 및 결 과
○ 곡선궤도법을 적용한 발혈부위 추정 공식을 유도하고, 소프트웨어(NST)를 개발
○ 실험을 통해 검증한 결과, 기존방법에 비해 오류율이 최대 65% 까지 감소
○ NST SW는 또한 기존의 방

연구결과
필요성 및 목표
○ 현재 혈흔형태분석에서 충격비산혈흔의 발혈부위 추정방법은 직선궤도법에 기초한 기법 및 이를 구현하는 소프트웨어만이 존재하나, 실제 혈액방울은 중력과 공기저항의 영향으로 포물선 운동을 함
○ 따라서 곡선궤도를 반영한 발혈부위 계산공식 및 소프트웨어의 개발이 필요
방 법 및 결 과
○ 곡선궤도법을 적용한 발혈부위 추정 공식을 유도하고, 소프트웨어(NST)를 개발
○ 실험을 통해 검증한 결과, 기존방법에 비해 오류율이 최대 65% 까지 감소
○ NST SW는 또한 기존의 방법인 직선궤도법에 의한 계산도 가능하며, 3D로 구현
기대성과
○ NST 소프트웨어 개발로 범죄현장 혈흔형태분석 시에 보다 정확한 발혈부위 추정이 가능
○ 고가의 외산SW 대체 가능

Abstract ▼

In bloodstain pattern analysis, an area of origin of an impact spatter can be evaluated using straight-line geometry. This method assumes blood droplets travel in straight-line trajectories. But blood droplets follow a parabolic trajectory due to gravity and air resistance. Errors occur when evaluat

In bloodstain pattern analysis, an area of origin of an impact spatter can be evaluated using straight-line geometry. This method assumes blood droplets travel in straight-line trajectories. But blood droplets follow a parabolic trajectory due to gravity and air resistance. Errors occur when evaluating an area of origin using straight-line geometry. So we calculated and derived the algorithm of finding the area of origin applying the effect of gravity by Newtonian mechanics.
Equation of motion of a blood drop is given by Newton's equation of motion. Solution of the equation of motion of a blood drop results in 5 unknowns in the solution and 3 equations. It is considered that solving this equation is not possible. From the stains, we can get more information: angle of impact and directional angle.
We use the impact velocity formula of the blood drop. So we can calculate the height of the area of origin of the impact spatter. Based on these equation, we developed new software to calculate the area of origin by the parabolic trajectory method. We generated impact spatters using the experimental apparatus and used cow blood. Blood stains were generated at X-axis distance 30, 40, 50 cm respectively to examine the effect of gravity and air resistance. Using our new software (NST), we calculated the area of origin of the impact spatter. Estimated value in the X-coordinate is almost coincident with true value. The error rates are below 2.6%. Estimated value in the Y-coordinate is almost coincident with true value. The error rates are below 0.5%. In the straight-line method, as distance between the origin and the stain increases, the estimated Z-value goes higher. The maximum error rate is 9.8%. In the parabolic method, as distance bw the origin and the stain increases, the estimated value goes higher. The maximum error rate is 6.6%. The parabolic method reduces the error rates by 65%, 33% in the distance 40, 50 cm resp.
The parabolic method reduces the error rates by 65%, 33% in the distance 40, 50 cm resp. NST Software can calculate more accurate area of origin than the straight-line method software. NST Software can also calculate the area of origin by the straight-line method. More precise algorithm including the effect of air resistance is being studied.