• 대한교통학회지
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• 제19권5호
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• pp.109-117
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• 2001

본 논문은 특정 도로조건에 대하여 어떤 형태의 중앙선침범 예방시설물을 설치할 것인가에 대한 비용-효율적인 기준 마련을 목표로 삼고, 그 첫 단계로 중앙선침범사고 예측모델을 개발하였다. 예측모델은 중앙선침범 예측과 침범후 대향차량과의 충돌 확률로 이루어진다. 중앙선침범 예측은 교통량에 관계되며, 이는 Hutchinson과 Kennedy(1966)의 연구에서 인용하였다. 중앙선을 침범한 후 대향차량과의 충돌 확률은 중앙선을 침범하는 차량의 침범각의 분포에 따라 주행거리와 주행시간을 계산하고, 음지수분포로 가정한 대향차량의 출현에 간격수락이론을 적용하였다. 제시된 중앙선침범사고 예측모델을 통하여 예측된 사고건수는 사고감소에 대한 편익을 계산할 수 있게 하며, 이는 중앙선침범예방시설 설치비용 계산과 함께 경제성분석을 가능하게 하여 비용-효율적인 중앙선침범예방시설 설치기준마련에 도움을 줄 것이다.

• Advances in pediatric surgery
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• 제10권1호
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• pp.31-34
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• 2004

The laparoscopic splenectomy (LS) became popular over the last 10 years. The advantage of LS over open splenectomy (OS) includes short hospital stay, improved cosmesis, less development of postoperative intestinal ileus, and less analgesics required. The purpose of this study is to evaluate the outcome of LS at Asan Medical Center from January 1999 to January 2003. The records of 14 consequent children who underwent splenectomy were reviewed retrospectively. Patients characteristics, morbidity, mortality, operative time, blood loss, and hospital stay were analyzed., Seven patients age 5 to 15 years underwent LS under the indications: idiopathic thrombocytic purpura (ITP, n=3), hereditary spherocytosis (n=3), and myelodysplastic syndrome (n=l). Seven patients, age 7 to 16 years, underwent OS during the same period for ITP (n=7). Median operative time was 120 mInutes (80 to 170 mins.) in OS, and 270 minutes (110 to 480 mins,) in LS (p<0.05). Median length of hospital stay was 6 days (3 to 8) in OS, and 4 days (3 to 6) in LS (p>0.05). Median splenic length was 12.0cm (9.2 to 18.0) in OS, 14.0 cm (10.0 to 19.5) (p>0.05). Accessory spleens were identified in 3 of 7 LS and 1 of 7 OS cases. In the LS group, there was no conversion to open surgery. Two patients in LS required blood transfusion postoperatively. LS in children can be performed as effectively and safely as OS.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5913-5916
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• 2015

Gestational trophoblastic neoplasia (GTN) is the malignant form of gestational trophoblastic disease. In non-metastatic GTN, the outcomes of treatment are impressive with methotrexate (MTX) or actinomycin D. We retrospectively reviewed the outcomes of non-metastatic GTN treated at our center from January, 1999 to December, 2013. One hundred and nine patients were recruited to the study. The median age was 33.1 years and over 90% were referral cases. Abnormal vaginal symptoms developed in 37.6% while 56.4% were asymptomatic. The most common antecedent pregnancy was a complete mole (92.7%) with the median interval time from antecedent pregnancy to GTN development being 2.0 months. The median pretreatment B-hCG was 5,624 mIu/ml. The most common first line treatment was methotrexate (MTX) and folinic acid (91.7%) followed by weekly MTX (4.6%), etoposide+ MTX+actinomycin D (EMA) (2.8%), and actinomycin D (0.9%), with the median number of cycles at 5.0. The positive response to first line chemotherapy was 73.8%. The patients were given subsequent chemotherapeutic regimens after resistance to the first line therapy and showed a final remission rate of 89.9%.The significant factor that was frequently found in patients who were non-responders to the first line treatment was a hysterectomy procedure. Two patients developed lung metastasis and brain metastasis at one and four years after the first treatment, respectively. In conclusion, the outcomes of non-metastatic GTN were excellent. However, the patients need long term follow up due to the possibility of developing multiple organ metastases.

• 한국ITS학회 논문지
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• 제17권5호
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• pp.143-150
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• 2018

RF 기반 고속 무선통신 기술이 급속히 발전함에 따라 무선 주파수 대역을 기반으로한 IoT 네트워크용 디바이스가 빠르게 보급되고 있으나, 최근 IoT 네트워크 디바이스의 급속한 확산 속도에 비하여 RF 통신 기술의 발전속도가 미치지 못하고 있다. 이러한 상황에서 가시광원을 송신수단으로 사용하는 OWC 기술은 RF 기반 무선 통신의 대역 고갈 문제를 극복 할 수 있는 기술로서 주목받고 있으나, OWC용 데이터 수신 중 발생하는 LED 조명 형태의 왜곡으로 인하여 LED 조명 검출율이 저하되고 RoI의 설정이 부정확해지는 현상이 발생 할 가능성이 있다. 본 논문에서는 Adaptive Median Filter를 적용한 저속 카메라 통신용 LED 조명 검출 알고리즘을 제안하였다. 이를 통해 명확한 RoI 설정 및 LED 조명 검출이 가능할 것으로 사료되며, 본 연구결과를 통해 RF 기반 무선 통신기술의 보완재로서의 역할을 효율적으로 수행 할 수 있을 것으로 판단된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.137-138
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• 2023

This study proposed the optimal mixing time for pre-mixed cement and post mixed cement using the statistical analysis method of box plots. Pre-mixed cement can prevent material seegregation, strength loss, and quality variation if mixed for at least 60 seconds, and the data median is shown to be within the box range. Post-mixed cement should be mixed for at least 180 seconds to prevent material segregation, strength loss, and quality variation, and compressive strength tends to increase with longer vibrating times. Therefore, it is suggested that using pre-mixed cement can shorten the vibrating time and increase the productivity of the concrete.

• Asian Pacific Journal of Cancer Prevention
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• 제15권20호
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• pp.8893-8900
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• 2014

Dysregulated expression of microRNAs (miRNAs) has been shown to be closely associated with tumor development, progression, and carcinogenesis. However, their clinical implications for gastric cancer remain elusive. To investigate the hypothesis that genome-wide alternations of miRNAs differentiate gastric cancer tissues from those matched adjacent non-tumor tissues (ANTTs), miRNA arrays were employed to examine miRNA expression profiles for the 5-pair discovery stage, and the quantitative real-time polymerase chain reaction (qRTPCR) was applied to validate candidate miRNAs for 48-pair validation stage. Furthermore, the relationship between altered miRNA and clinicopathological features and prognosis of gastric cancer was explored. Among a total of 1,146 miRNAs analyzed, 16 miRNAs were found to be significantly different expressed in tissues from gastric cancer compared to ANTTs (p<0.05). qRT-PCR further confirmed the variation in expression of miR-193b and miR-196a in the validation stage. Down-expression of miR-193b was significantly correlated with Lauren type, differentiation, UICC stage, invasion, and metastasis of gastric cancer (p<0.05), while over-expression of miR-196a was significantly associated with poor differentiation (p=0.022). Moreover, binary logistic regression analysis demonstrated that the UICC stage was a significant risk factor for down-expression of miR-193b (adjusted OR=8.69; 95%CI=1.06-56.91; p=0.043). Additionally, Kaplan-Meier survival curves indicated that patients with a high fold-change of down-regulated miR-193b had a significantly shorter survival time (n=19; median survival=29 months) compared to patients with a low fold-change of down-regulated miR-193b (n=29; median survival=54 months) (p=0.001). Overall survival time of patients with a low fold-change of up-regulated miR-196a (n=27; median survival=52 months) was significantly longer than that of patients with a high fold-change of up-regulated miR-196a (n=21; median survival=46 months) (p=0.003). Hence, miR-193b and miR-196a may be applied as novel and promising prognostic markers in gastric cancer.

• Journal of Korean Neurosurgical Society
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• 제52권4호
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• pp.334-338
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• 2012

Objective : We compared the survival time between patients with multiple gamma knife radiosurgery (GKRS) and patients with a single GKRS plus whole brain radiation therapy (WBRT), in patients with multiple metachronous brain metastases from lung cancer. Methods : From May 2006 to July 2010, we analyzed 31 patients out of 112 patients who showed multiple metachronous brain metastases. 20 out of 31 patients underwent multiple GKRS (group A) and 11 patients underwent a single GKRS plus WBRT (group B). We compared the survival time between group A and B. Kaplan-Meier method and Cox proportional hazards were used to analyze relationship between survival and 1) the number of lesions in each patient, 2) the average volume of lesions in each patient, 3) the number of repeated GKRS, and 4) the interval of development of new lesions, respectively. Results : Median survival time was 18 months (range 6-50 months) in group A and 6 months (range 3-18 months) in group B. Only the average volume of individual lesion (over 10 cc) was negatively related with survival time according to Kaplan-Meier method. Cox-proportional hazard ratio of each variable was 1.1559 for the number of lesions, 1.0005 for the average volume of lesions, 0.0894 for the numbers of repeated GKRS, and 0.5970 for the interval of development of new lesions. Conclusion : This study showed extended survival time in group A compared with group B. Our result supports that multiple GKRS is of value in extending the survival time in patients with multiple metachronous brain metastases, and that the number of the lesions and the frequency of development of new lesions are not an obstacle in treating patients with GKRS.

• Childhood Kidney Diseases
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• 제20권1호
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• pp.18-22
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• 2016

Purpose: The previous reports regarding VUR resolution were not precise due to early frequent surgical intervention. We evaluated the spontaneous resolution (SR) rate and the incidence of new renal scars in primary VUR, focusing on severe reflux. Methods: Medical records of 334 patients with primary VUR who were on medical prophylaxis without surgery for 1 to 9 years, were retrospectively reviewed. Medical prophylaxis was initiated with low-dose antibiotic prophylaxis or probiotics. Radioisotope cystourethrography was performed every 1 to 3 years until SR of reflux. New renal scar was evaluated with follow-up $^{99m}Tc$ DMSA renal scan. Results: The SR rates decreased as VUR grades were getting higher (P=0.00). The overall and annual SR were 58.4% and 14.9%/yr in grade IV reflux and 37.5% and 9.3%/yr in grade V reflux. The median times of SR were 38 months in grade IV reflux and 66 months in grade V reflux. The probable SR rates in grade IV and V reflux were 7.8% and 8.9% in the 1st year, 46.0% and 30.8% in the 3rd year and 74.4% and 64.4% in the 5th year. The incidences of new renal scars between low to moderate reflux and severe reflux showed no significant difference (P=0.32). Conclusion: The SR rates of severe primary VUR were higher than previously reported and most new renal scars were focal and mild.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.319-325
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• 2003

The fragility curves of seismic retrofitted bridges by steel jacketing of bridge columns and restrainers at expansion joints after the 1994 Northridge earthquake are developed. Fragility curves are represented by lognormal distribution functions with two parameters(fragility parameters consisting of median and log-standard deviation) and developed as a function of peak ground acceleration (PGA). Two parameters in the lognormal distribution are estimated by the maximum likelihood method. The sixty ground acceleration time histories for Los Angeles area developed for FEMA SAC project are used for the dynamic analysis of the bridges and a computer code is developed to calculate hysterestic parameters of bridge columns before and after steel jacketing. The effect of retrofit is expressed in terms of the increase of the median value of the fragility curve for the retrofitted bridge from that of the bridge before retrofit. The comparison of fragility curves of the bridges before and after column retrofit demonstrates that the improvement of the bridges with steel jacketing on the seismic performance is excellent for the damage states defined in this study. The comparison of fragility curves of the bridges before and after restrainers at expansion joints also shows the improvement in the seismic performance of restrained bridges for the severe damage states.

• Asian Pacific Journal of Cancer Prevention
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• 제17권3호
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• pp.1357-1362
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• 2016

Metastatic gestational trophoblastic neoplasia (GTN) is an uncommon cancer. The principal treatment consists of chemotherapy with or without surgery or radiotherapy. We here retrospectively reviewed the outcomes of metastatic GTN treated at our institute between January, 1999 and December, 2013. Sixty-three patients met the criteria. The median age was 30.0 years and almost 90% were referral cases. Nearly 40% of the studied patients presented with vaginal bleeding while 22.2% were asymptomatic. The most common antecedent pregnancy was hydatidiform mole (57.1%) followed by term pregnancy (20.6%). The median interval time from antecedent pregnancy to the development of GTN was three months and the median pretreatment B-hCG was 58,274 mIU/ml. Stage III (74.6%) was the most common staging followed by stage IV (20.6%) and stage II (4.8%). The most frequent surgery was hysterectomy (31.7%). Thoracotomy and craniotomy were performed in three and two patients, respectively. The most common first line chemotherapy regimen was methotrexate and folinic acid (36.5%) followed by EMA (etoposide, methotrexate, actinomycin D) (34.9%), EMACO (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine) (17.5%) with the remission rate of 66.7%. Nearly one-third of the patients were given a subsequent chemotherapy regimen after failure with the first line therapy and showed a final response rate of 73.0%. However, in stage IV, the response to first line treatment was only 38.5%. In conclusion, the outcomes of metastatic GTN were poor especially with the higher stages.