• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.168-172
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• 2007

소유역의 배수시설물 설계를 위한 확률강우량 결정에는 일반적으로 건설교통부 (2000)에 의해 제시된 강우강도식을 이용하며, 강우의 지속시간이 10분이하인 경우에도 통상 제시된 강우강도식의 지속시간 최소단위인 10분을 그대로 적용하는 것이 일반적이다. 따라서 도달시간이 수 분 정도인 도로 배수시설물의 경우에는 상대적으로 과대설계가 될 가능성이 크다. 본 연구에서는 이러한 문제점을 극복하고자 모포마 분포를 시자료에 적용하여 분단위 연최대치 강우계열을 구성하고 이를 빈도해석하여 확률강우량을 추정하였다. 1분단위 강우자료(MMR 자료)를 이용하여 빈도해석을 수행한 결과 기존 건설교통부 (2000)에 의해 제시된 강우강도식은 분단위로 내삽할 수 없음을 확인하였다. 60분 집성자료를 모포마 분포에 적용하여 추정한 지속시간별 분단위 연최대치 강우계열은 관측된 분단위 연최대치 강우계열의 특성을 적절히 설명할 수 있는 것으로 파악되었다. 따라서 모포마 분포를 이용하는 경우 시단위자료를 이용하여 1분단위 자료의 특성 재현이 가능한 것으로 판단된다. 60분 집성자료와 시단위 자료를 이용하여 모포마 분포에 각각 적용하여 IDF 관계를 유도한 경우 그 차이는 매우 미미한 것으로 나타났다. 아울러 사용된 자기상관함수에 따른 차이도 미미한 것으로 확인되었다. 따라서 모포마 분포는 시단위 자료로 부터 60분 이하의 지속시간에 대한 연최대치 강우계열을 적절히 재현할 수 있는 방법인 것으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.271-281
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• 2008

To determine the flood protection elevation (FPE) in urban built-up areas, this study examines four possible methods: using the highest flood elevation in the past, extending base flood elevations of nearby watercourse to inland, and two simulation methods of inland flood under the same rainfall used in the watercourse planning nearby. According to the case study of the Jang-An Drainage Area, Seoul, the highest flood elevation in the past and simulation results of inland flood under the same rainfall in the watercourse planning nearby tend to get similar results, while extending base flood elevations of nearby watercourse to inland shows much higher elevations than other results. Meanwhile, cost-benefit analysis, when regulating residential/commercial uses below the FPE by each of four methods, suggest that planners need to consider carefully the economic feasibility of FPE used to choose appropriate methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.361-365
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• 2005

Proxy signature schemes which allows original signer to delegate proxy signer to sign message on its behalf have a considerable amount of interest from researchers since Mambo[1] and have found many practical applications such as distributed network, Grid computing and electronic commerce. Araki[6] extended them to multi-level proxy signature. But it could not satisfy some security requirement. In this paper we propose a protocol to delegate signing right to another entity for multi-level proxy signature. Our protocol do not require secure channel and guarantee that nobody is able to repudiate delegation or acceptance of signing right, it is impossible for anyone to generate signature except designed and original signer can withdraw the delegation before expiration if it is necessary.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.332-332
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• 2017

본 연구는 내성천에 대한 장기간 수문 모니터링을 결과를 이용하여 사주 위에 활착하는 식생의 변화 과정을 추정하고 증명하였다. 2012년부터 2016년은 영주댐이 완공되어 정상 운영을 시작하기 이전인 시기로 자연 흐름이 마지막으로 지속된 시기이다. 이 기간에 대한 수문 모니터링 정보는 댐 하류 주요 지점에 대한 수위, 단면 측량, 유량 측정 자료, 사진 모니터링 자료를 정기적으로 조사하였다. 이러한 모니터링 결과는 내성천을 따라 형성된 관심 사주에 초점을 맞추어 분석하였다. 사주에 형성된 식생은 홍수위와 그에 따른 소류력에 의해 하상재료인 모래가 퇴적되느냐 침식되느냐에 따라 식생의 활착 및 감소가 결정된다. 이는 관심 지점에 대한 정기적인 사진 모니터링 결과에서도 확인할 수 있었다. 영주댐은 2016년 말부터 담수에 의한 정상적인 운영을 시작하여 발전 방류를 위한 조절 댐의 역할을 하고 있다. 영주댐 운영 후 내성천에 미치는 다양한 영향을 판단하기 위해 지난 5년간 모니터링 자료는 비교 자료로서 소중한 가치를 가질 것이다.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.107-117
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• 2002

In this paper we present the optimal replacement policies following the expiration of combination warranty. We consider two types of combination warranty policies: renewing warranty and non-renewing warranty. The criterion used to determine the optimal replacement period is the expected cost rate per unit time from the user'perspective. The optimal maintenance period following the expiration of combination warranty is obtained. Some numerical examples are presented for illustrative purpose.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1162-1166
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• 2009

본 논문에서는 공간상의 한 점에 대한 연속시간 강우모델로 시간단위의 통계특성을 재현하는데 유용하다고 알려진 BLRPM(Bartlett-Lewis Rectangular Pulse Model)을 이용하여, 측우기 자료를 포함하는 서울지점의 일강우 자료를 분해하고 지속시간별로 집성하여 모의된 시단위 단기 강우의 정량적 장기변화 특성을 분석해 보았다. 모의자료의 전이확률과 발생빈도 분석결과, 측우기 관측계열(CWK)에 비해 근대 우량계 관측계열(MRG)의 무강우 지속기간은 길어지고 강우지속기간은 짧아졌음을 알 수 있다. 이는 과거에 비해 근래의 강우지속기간이 짧아졌음을 의미하고, 근래 강우량의 양적증가와 같이 고려해 보면 근래의 강우강도가 과거보다 매우 높아졌음을 증명해 준다. 1960년대 전후로 구분한 자료계열(BCC와 ACC)에 대하여 지속시간별 모의 강우량의 평균과 분산의 비(증감률)를 월별로 비교한 결과, 전반적으로 9월이 증가의 정도가 가장 컸고 8월도 비교적 큰 증가 경향을 보였다. 그러나 6월은 오히려 약간 감소한 경향을 나타냈다.

• Journal of Gastric Cancer
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• v.8 no.3
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• pp.141-147
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• 2008

Purpose: The aim of this study was to compare the short-term operative outcomes of laparoscopy-assisted total gastrectomy (LATG) with those of open total gastrectomy (OTG) for patients suffering with advanced upper gastric cancer. Materials and Methods: Of the 47 patients who underwent LATG with $D1+{\beta}$ or D2 lymphadenectomy from July 2004 to March 2008, 29 patients with pathologically proven advanced gastric cancer were compared with 35 patients who underwent conventional OTG during the same time period. The comparison was based on the clinicopathological characteristics, the surgical outcome, the follow-up survival and tumor recurrence. Results: The patients' age, gender and body mass index were similar between the two groups. However, there were statistically differences in tumor size ($9.2{\pm}3.9$ vs $6.1{\pm}3.6cm$, P=0.002) and the proximal resected margin ($2.1{\pm}2.0$ vs $3.6{\pm}2.1cm$ P=0.004). There was no significant difference in most of the peri- and post-operative courses such as the time to first flatus, the time to starting a solid diet and the length of the hospital stay, except for a longer operating time (289.0 vs. 361.3 minutes, P<0.001) in the LATG group. The complication rate was higher in the LATG group (13.8%) than that in the OTG group (5.7%). The mean overall survival and disease free survival times were 32 and 31 months, and 24 and 28 months, respectively, with an average 18.8 months follow-up duration. The main recurrent sites were peritoneum and lymph node in both groups. Conclusion: The early results of the current study suggest that LATG for AGC is technically feasible and it does not show any inferiorities of the postoperative outcomes as compared to those of conventional open total gastrectomy.

• Radiation Oncology Journal
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• v.18 no.1
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• pp.27-31
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• 2000

Purpose : The aim of this study was to investigate treatment results, toxicity and efficacy of hypefractionated radiation therapy combined with paclitaxel for paraaortic node recurrence in cervix cancer. Materials and Methods: Between September 1997 to March 1999, 12 patients with paraaortic node recurrence in cervix cancer who previously received radical or postoperative radiotherapy were treated with hypefractionated radiation therapy combined with paclitaxel. Of these, 2 patients who irradiated less than 30 Gy were excluded, 10 patients were eligible for this study. Median age was 51 years. Initial FIGO stage was 1 stage IBI, 2 stage IIA, 7 stage IIB. For initial treatment, 7 patients received radical radiotherapy and 3 received postoperative radiotherapy. The paraaortic field encompassed the gross recurrent disease with superior margin at T12, and inferior margin was between L5 and S1 with gap for previously pelvic radiation field. The radiation field was initially anterior and posterior opposed field followed by both lateral field. The daily dose was 1.2 Gy, twice daily fractions, and total radiotherapy dose was between 50.4 and 60 Gy(median, 58.8 Gy). Concurrent chemotherapy was done with paclitaxel as a radiosensitizer. Dose range was from 20 mg/m$^{3}$ to 30 mg/m$^{3}$ (median, 25 mg/m$^{3}$), and cycle of chemotherapy was from 3 to 6 (median, 4.5 cycle). Follow-up period ranged from 3 to 21 months. Results : Interval between initial diagnosis and paraaortic node recurrence was range from 2 to 63 months (median, 8 months). The 1 year overall survival rate and median survival were 75$\%$ and 9.5 months, respectively. The 1 year disease free survival rate and median disease free survival were 30$\%$ and 7 months, respectively. At 1 month after treatment, 4 (40$\%$) achieved a complete response and 6 (60$\%$) experienced a partial response and all patients showed response above the partial response. There was distant metastasis in 6 patients and pelvic node recurrence In 2 patients after paraaortic node irradiation. There was 2 patients with grade 3 to 4 leukopenla and 8 patients with grade 1 to 2 nausea/ vomiting which was usually tolerable with antlemetic drug. There was no chronic complication in abdomen and pelvis during follow up period. Conclusion : hypefractionated radiation therapy combined with paclitaxel chemotherapy diosensitizer showed high response rate and few complication rate in paraaortic node recurrence in cervix cancer Therefore, present results suggest that hypefractionated radiation therapy combined with paclitaxel chemotherapy can be used as optimal treatment modality in this patients.

• Journal of Convergence for Information Technology
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• v.10 no.3
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• pp.67-75
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• 2020

This paper investigated the information spillover effect between stock market and bond market with the KOSPI daily index and MMF yield data. The overall analysis period is from May 2, 1997 to August 30, 2019. The empirical analysis was conducted by dividing the period from May 2, 1997 to December 30, 2008 before the global financial crisis, and from December 30, 2008 to August 30, 2019 after the global financial crisis, and the overall analysis period. The analysis shows that the EGARCH model considering asymmetric variability is suitable. The price spillover effect and volatility spillover effect existed in both directions between the stock market and the bond market, and the price transfer effect was greater in the period before the global financial crisis than in the period after the global financial crisis. Asymmetric volatility in information between stock and bond markets appears to exist in both markets.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.1
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• pp.48-53
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• 2004

Purpose: Besides interferencence of esophageal motor function by the nasogastric tube, a decline of the positive gastro-esophageal pressure gradient caused by intermittent positive pressure ventilation seems to have a major role in the pathogenesis of gastroesophageal reflux (GER) in mechanically ventilated preterm infants. The aim of this study was to determine the incidence of GER and associated risk factors in mechanically ventilated preterm infants. Methods: Twenty four hour esophageal pH monitorings were performed using a antimony electrode on 11 mechanically ventilated preterm infants in Neonatal Intensive Care Unit in Pusan National University Hospital. We evaluated the following reflux parameters; reflux index, reflux episodes/hour, reflux episodes ${\geq}5min/hour$, duration of longest episode, and percent episodes ${\geq}5min$. Patients were considered to have significant GER if more than 2 among 5 parameters were satisfied. Results: The mean gestational age of the patients was 30.9 weeks, mean birth weight was 1,568 g, and mean age at the time of pH monitoring was 2.8 days. Significant GER was detected in 4 patients (36.4%). There was no relationship between the incidence of GER and gestational age, birth weight, postnatal age, or the ventilator settings. Conclusion: The incidence of GER in mechanically ventilated preterm infants was similar, compared with other previous studies. Associated risk factors of GER in these patients were not detected. Therefore, mechanical ventilation in preterm infants does not seem to be the high risk factor of GER.