• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.165-169
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• 2011

실제 화재의 위험성을 평가하는 가장 좋은 방법은 직접 실재 화재 조건을 모사 또는 구현하여 평가하는 방법이다. 그러나, 비용과 시간 및 환경 문제를 생각한다면 쉬운 일은 아니다. 따라서 단위 재료를 태우거나, 전산 시뮬레이션을 활용하여 화재를 예측하는 방법을 활용한다. 본 연구에서는 콘칼로리미터 실험 결과를 기초 데이터로 실제 화재 실험인 room corner test의 총열방출량을 추정하였다. 그 결과 가연물의 부피 및 밀도와 보정상수를 활용하여 실제 총열방출량에 근접한 결과값을 얻을 수 있었으며, 산출된 총열방출량을 근거로 전산시뮬레이션을 수행, 시뮬레이션 결과값을 통해 재실자의 화재 및 연기에 대한 위험성 평가를 할 수 있었다. 본 결과를 통해 화재 시뮬레이션 수행 시 가연물에 따른 화재에 의한 위험성 평가를 할 수 있을 것으로 보인다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.103-105
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• 2014

선박의 운항분포는 교량충돌확률이나 선박충돌위험도 등을 계산할 때 매우 중요한 요인으로 작용하지만, AASHTO모델이나 해상교통안전진단에서의 근접도 평가모델 등 많은 충돌 또는 위험도 계산 모델에서는 선박의 운항분포가 단순한 정규분포임을 가정하고 있다. 따라서 특정 항로나 해역에서의 정확한 충돌, 위험 또는 안전 등에 관한 확률을 구하고자 할 경우에는 그 항로나 해역의 특성에 맞는 선박 운항분포를 사용해야 한다. 이 연구에서는 일주일간의 통항선박 위치정보(AIS정보)를 이용하여 다양한 특성을 가지는 항로별로 각각 고유한 특성의 선박 운항분포를 찾아내기 위해, sech 함수를 이용한 새로운 충돌위험도 평가법에서 피항구역의 문턱값을 결정하는 방법을 분석하고 실제 상황에 적용 가능한 식을 개발하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.319-320
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• 2022

본 논문에서는 '지능형 해상교통정보 서비스'로 축적된 선박 위치데이터를 가공하여 선박의 조우상황 데이터를 추출하고 분석하였다. 선박의 위치, 침로, 속력을 통해 TCPA, DCPA와 선박간 거리를 계산함으로써 선박의 충돌위험 인지 후 회피 상황에서 보이는 데이터의 형태와 분포를 분석하였다. 추후 상대방위와 SOG가 TCPA 변화량에 미치는 영향에 대한 연구가 진행되면, 실제 사용자의 충돌위험 판단과 근접한 충돌위험도 분석 모델로 활용할 수 있을 것으로 보인다.

• Radiation Oncology Journal
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• v.29 no.2
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• pp.71-82
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• 2011

Purpose: To evaluate the biochemical control rate and the rate of side effects after performing permanent brachytherapy of localized prostate cancer. Materials and Methods: 67 patients with localized prostate cancer were treated with brachytherapy between April 2007 and December 2008. Of these, 43 patients who were followed up and did not receive external radiotherapy were evaluated for the change in prostate specific antigen (PSA) level and the occurrence of side effects. In total, 18 patients were classified as low risk, 19 patients as intermediate risk, and 6 patients as high risk. The prescription dose was 145 Gy. Results: A PSA increase greater than 2 ng/mL occurred in 2 patients (4.7%). Radiation Therapy Oncology Group (RTOG) grade 1 and 2 acute urologic complications (UC) occurred in 40 and 3 patients, respectively. Further, 5 patients had RTOG grade 1 acute rectal complication (RC). The numbers of RTOG grade 1, 2, and 3 chronic UC were 1, 4, and 1, respectively. The numbers of RTOG grade 1, 2, and 4 chronic RC were 5, 10, and 3, respectively. The statistically significant risk factors (RF) of acute RC were the minimal dose in the most irradiated 0.1 cc volume ($D_{0.1cc}$, p=0.041) and absolute volume receiving 150% of the prescribed dose ($V_{150cc}$, p=0.038) in the entire rectum (ER). The percentage ($V_{100%}$, p=0.019) and absolute volume ($V_{100cc}$, p=0.047) in the involved rectum (IR) were also statistically significant. The RF of chronic RC were $V_{100%}$ (p=0.011) in the ER and the $D_{0.1cc}$ (p=0.049), $V_{100cc}$ (p=0.023) in the IR. The number of used seeds were related with acute UC (p=0.028). Conclusion: Permanent brachytherpy of localized prostate cancer showed a favorable short term biochemical control rate. As such, selective intermediate and high risk patients can be managed with permanent brachytherapy. The effort to reduce rectal complication is also necessary.

• Journal of Navigation and Port Research
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• v.43 no.4
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• pp.250-255
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• 2019

The objective of this study was to analyze the risk of collision accidents to the VTSOs (Vessel Traffic Service Operators) as small ferries and fishing boats are expanded for monitoring targets. The VTSOs was surveyed, the scale of the small vessels defined and the course of general cargo vessels and small vessels along the Busan VTS area investigated for three days. From calculating the risk with CoRI, patterns of increased or decreased risk due to course deviation were similar, and there was no significant difference between the maximum values and the minimum values. In addition, most VTSOs responded that the minimum time required was approximately three minutes to safely instruct in encounter situation, however, the collision risk with a small vessel is very rapidly changing within the three minutes, which is likely to increase the workload and decrease the concentration of the VTSOs. The objective of this study was to investigate the effect on VTSOs with respect to the expansion of small vessels as collision risk, it is expected that it will contribute to the establishment of a suitable scale for the target vessels for VTS through the analysis of each index of the CoRI model and various case studies.

• Journal of Navigation and Port Research
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• v.41 no.3
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• pp.93-102
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• 2017

When VTSOs (Vessel Traffic Service Operator) determine the degree of collision risk for two vessels, they consider comprehensive information about each vessel's course, speed, DCPA, TCPA, and encountering situation. In this study, we proposed a utility function based on the risk attitudes of VTSOs toward the Risk Index (RI). The RI was calculated using the risk of encounter, the risk of approach, and the risk of time for two vessels in order to predict each ship's collision risk from the VTS viewpoint. We obtained each coefficient of the RI and the risk attitude through a survey of collision risks among VTSOs of Korea. In order to verify whether the proposed utility is reasonable, we validated by applying the degree of collision risk to some historical cases of accidents in Busan port along with the Ship of ES value($ES_S$) of ES(Environmental Stress) model.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.447-454
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• 2017

Using two large coast guard ships at sea, we created four encounter situations ($000^{\circ}$, $045^{\circ}$, $090^{\circ}$, $135^{\circ}$) with high possibility of collision, from 3 NM up to 0.25 NM. As relative distance was gradually decreased, the subjects were measured at 0.25 NM intervals and perceived ship collision risk (PSCR) was determined by looking at the opponent ship. Characteristics were statistically analyzed using the obtained data. The purpose of this study was to analyze the characteristics of collision risk values obtained from twelve intervals, from 3 NM to 0.25 NM relative to encounter situations by curve fitting with appropriate polynomials, to determine the distance from which the change in perceived collision risk is greatest. As a result, an optimal regression equation for each distance interval was derived from each analysis direction. The greatest variation in average collision risk value was over the range 1.25 ~ 1 NM, and the collision risk value was largest at 1 NM. The maximum change in perceived collision risk was at 1 NM. These results can contribute to preventive guidelines to minimize human error in close proximity situations with a high probability of ship collision.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.303-309
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• 2017

To evaluate the usefulness of 3-dimensional brachytherapy(BT) planning technique based on CT in cervical cancer. Patients with cervical cancer underwent 2-D BT treatment planning and then CT scan with HDR intracavitary applicators in place with same positions. Dose was prescribed to Point A with 5Gy per fraction on 2-D BT planning. For 3-D BT planning, and dose was prescribed to the High risk CTV for BT (HR CTV) with 5Gy. The 3-D BT planning goal was to cover at least 90% of the HR CTV with target 5Gy isodose surface while limiting the dose to $2cm^3$ of bladder to less than 7.5 Gy, and $2cm^3$ of rectum to less than 5Gy. In one patient of 10 patients, $D_{2cm3}$ of rectal dose was over 5Gy and 6patients at $D_{2cm3}$ of bladder dose on 2-D BT planning. There was a tendency to underestimate ICRU bladder dose than ICRU rectal dose. CT based 3-D BT planning for cervical cancer will enable evaluation of dose distributions for tumor and critical organs at risk. So, rectal and bladder morbidity as well as geographic miss will be reduced in case of the bulky disease or uterine malposition.

• Fire Science and Engineering
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• v.25 no.3
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• pp.63-71
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• 2011

In this study, it was evaluated the fire risk of an electric heater as representative seasonal appliances. Two type of electric heaters were used in experiments. When electric heaters were operated, temperature variation was measured around the heater. Internal structure was understood by Nondestructive inspection. It was evaluated the tire risk of electric heaters, when flammable materials were positioned ear a heater. It was also estimated the probability of a tire in case of malfunction of a safety tip-over witch. When a heater was operated in a normal condition, temperature was maintained under $80^{\circ}C$ around the heater. The possibility of a fire is very high, when a heater is covered with flammable materials or malfunction of safety parts (safety tip-over switch, anti-overheating devices).

• Industry Promotion Research
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• v.8 no.4
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• pp.29-36
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• 2023

In order to prevent industrial accidents, this study presented a methodology to ensure that risk aggravating factors are reflected in risk assessments at manufacturing sites and demonstrated it by applying it to actual manufacturing sites. As a result of a statistical analysis of all 242,906 accidents that occurred in the manufacturing industry over the past 10 years, new workers less than 6 months old, foreign workers, older workers over 55 years old, and jobs where hands and arms are exposed to risk areas, Non-routine work performed from 9 o'clock to 12 o'clock showed a significantly high accident rate. In addition, a weighted value was applied to estimate the possibility of an accident at the risk determination stage through focus group interviews. Through the results of this study, risk weighting factors can be quantitatively reflected in risk assessment, which is meaningful in preventing accidents by evaluating the size of the identified risk closer.