• 한국정보전자통신기술학회논문지
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• 제10권5호
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• pp.372-379
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• 2017

소프트웨어 개발과정동안 소프트웨어 신뢰성 요인은 매우 기본적인 사항이다. 소프트웨어 고장파악을 위한 무한고장 비동질적인 포아송 과정을 이용할 때 고장발생률 혹은 위험함수가 일정하거나 증가 또는 감소하는 속성을 가진다. 본 논문에서는 소프트웨어 신뢰 성능에 관한 효율성을 비교하는 자유도에 의존하는 카이제곱 분포를 적용한 신뢰성 모형을 제안하였다. 효율적인 모형을 평가하기 위하여 평균제곱오차(MSE)와 결정계수($R^2$)를 이용하고 최우추정법과 수치 해석적 방법을 사용하여 모수추정 알고리즘이 수행되었다. 제안하는 카이제곱분포의 자유도를 이용한 신뢰성 모형을 위해 실제 고장 간격 데이터를 사용한 고장 성능 분석이 적용되었다. 고장데이터 분석은 카이제곱분포의 자유도에 근거한 강도함수를 기준으로 비교되었다. 데이터 신뢰성을 확인하기 위하여 라플라스 추세검정이 적용되었다. 본 연구에 제안된 카이제곱분포의 자유도는 다양한 고장현상을 표현 할 수 있기 때문에 (결정계수가 90% 이상), 신뢰성 분야에서 활용 할 수 있는 모형으로 활용 할 수 있다. 이 연구 결과를 적용하면 소프트웨어 개발 설계자에게 다양한 자유도를 적용하여 소프트웨어 고장패턴을 예측함으로서 효율적인 모형을 개발하는데 표준 지침으로 적용 할 수 있다.

• 한국정보전자통신기술학회논문지
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• 제11권4호
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• pp.460-466
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• 2018

정보기술의 발달로 컴퓨터 소프트웨어 시스템의 규모는 끊임없이 확장되고 있다. 소프트웨어 개발에 대한 신뢰성 및 비용은 소프트웨어 품질에 큰 영향을 미치고 있다. 본 연구에서는 소프트웨어 고장 간격시간 자료를 바탕으로 NHPP 모형에서 Type-2 Gumbel과 Erlang 분포의 형상모수를 따르는 수명분포에 근거한 소프트웨어 개발 비용모형에 관한 특성을 비교하고, 분석하였다. 그 결과, Go-Okumoto 모형 및 제시한 모형인 Erlang 모형과 Type-2 Gumble 모형에 대한 비용곡선의 추세는 모두 초기단계에서 감소하다가, 고장시간이 지나는 후반부에 가서는 점차 증가하는 결과를 보였다. 또한, Erlang 모형과 Type-2 Gumble 모형을 비교한 결과, Erlang 모형이 소프트웨어 출시시기가 빠르고, 출시시점의 비용도 경제적임을 알 수 있었다. 본 연구를 통하여, 소프트웨어 운용자들은 소프트웨어 출시시기 이후에 결함이 감소되도록 운영단계보다 테스팅 단계에서 결함들을 제거해야 하며, 소프트웨어 개발비용에 관한 특성을 파악하는데 필요한 사전정보을 연구할 수 있을 것으로 기대된다.

• 대한기계학회논문집B
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• 제28권1호
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• pp.66-71
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• 2004

Airborne contaminant particles are intruded into optical disk drive(ODD) due to the flow caused by disk rotation and can be adhered to objective lens, which causes read/write errors. Such a phenomenon can be a serious problem for high-density storage devices. The purpose of this paper is to understand the effect of particle contamination of objective lens in a CD-ROM drive on laser diode power and photo diode RF signal. The measurements of laser power and readout RF signal were carried out by using a laser power meter and a time interval analyzer, respectively. The parameters for estimating a readout-signal' distortion were its jitter and amplitude. Alumina(Al$_2$O$_3$) particles were used as test dust particles. The results show that the failure for data access happened as the degree of lens contamination was greater than 20％.

• Journal of Korean Neurosurgical Society
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• 제66권2호
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• pp.162-171
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• 2023

Objective : The goal of this study was to analyze the clinical outcomes of endoscopic third ventriculostomy (ETV) and endoscopic septostomy when shunt malfunction occurs in a patient who has previously undergone placement of a ventriculoperitoneal shunt. Methods : From 2001 to 2020 at Seoul National University Children's Hospital, patients who underwent ETV or endoscopic septostomy for shunt malfunction were retrospectively analyzed. Initial diagnosis (etiology of hydrocephalus), age at first shunt insertion, age at endoscopic procedure, magnetic resonance or computed tomography image, subsequent shunting data, and follow-up period were included. Results : Thirty-six patients were included in this retrospective study. Twenty-nine patients, 18 males and 11 females, with shunt malfunction underwent ETV. At the time of shunting, the age ranged from 1 day to 15.4 years (mean, 2.4 years). The mean age at the time of ETV was 13.1 years (range, 0.7 to 29.6 years). Nineteen patients remained shunt revision free. The 5-year shunt revision-free survival rate was 69% (95% confidence interval [CI], 0.54-0.88). Seven patients, three males and four females, with shunt malfunction underwent endoscopic septostomy. At the time of shunting, the age ranged from 0.2 to 12 years (mean, 3.9 years). The mean age at the time of endoscopic septostomy was 11.9 years (range, 0.5 to 29.5 years). Four patients remained free of shunt revision or addition. The 5-year shunt revision-free survival rate was 57% (95% CI, 0.3-1.0). There were no complications associated with the endoscopic procedures. Conclusion : The results of our study demonstrate that ETV or endoscopic septostomy can be effective and safe in patients with shunt malfunction.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8700-8706
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• 2015

고속철도차량 동력대차의 1차 구동장치는 모터 감속기와 견인전동기로 구성한다. 모터 감속기와 견인전동기는 기계적으로 일체형 결합 구조이지만, 상이한 기술 요구사항으로 인하여 이들의 완전 분해정비 주기는 서로 다르다(모터 감속기의 완전 분해정비 주기: $1.8{\times}10^6km$, 견인전동기의 완전 분해정비 주기: $2.5{\times}10^6km$). 따라서 불필요한 정비 횟수를 감소하기 위하여 신뢰성 중심 유지보수 관점에서 최적의 완전 분해정비 주기의 산정이 중요하다. 본 연구에서는 실제 유지보수 정비이력으로부터 두 구성품들에 대한 고장 결함나무 분석을 수행하고 각 하부부품들의 치명도를 고려한 고장률을 각각 평가하였다. 두 구성품에 대한 최적의 동일한 완전분해 정비주기는 기존의 총 예방정비 비용을 감소하기 위하여 유전자 알고리즘으로 부터 얻었다. 이 알고리즘에서 각 개체를 구성하는 유전자는 최소 예방 정비주기이며, 이의 조합으로 구성된 세대별 개체의 적합도함수는 총 정비비용의 역수로 공식화하여 얻는다. 최소공배수에 의한 방법은 기존 대비 4%만 감소하지만, 유전자 알고리즘에 의한 최적의 동일 완전분해 정비주기는 225만km로서 기존 방법의 총비용과 비교하여 약 14% 감소하였다.

• 한국임상수의학회지
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• 제30권1호
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• pp.57-60
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• 2013

개에서 포도중독에 의한 신부전 치료결과에 대한 임상적 분석을 위하여 205-2008년 기간 중 강원대학교 수의과대학 동물병원에 내원한 환자의 의료기록부를 분석하였다. 총 11두 (암컷 8두) 중 4두는 완전히 회복하였고, 3두는 폐사, 4두는 안락사로 처리되었다. 1두를 제외한 모든 환자는 포도를 섭취하였으나 정확한 섭취량은 알 수 없었다. 환자의 평균 연령은 5.3세 (범위 0.2-11.3세), 체중은 4.1 kg (범위 1.4-13 kg)였으며, 평균 입원기간은 7.1일 (범위 2-22일)로 나타났다. 모든 환자에서 구토와 식욕부진 증상을 보였으며, 일부 환자는 설사 (4두), 핍뇨 (5두), 무뇨 (4두) 소견을 보였다. 모든 환자에서 혈청 phosphorous, creatinine, BUN 농도가 증가된 소견을 보였으며, 고칼슘혈증 2두, 저칼슘혈증 2두, 나머지 7두는 정상소견이었다. 혈청 농도가 증가한 항목은 amylase 8두, ALP 7두, ALT 5두였으며, 혈액 가스 분석에서 8두는 대사성산증을 보였다. 경미하거나 중등도의 빈혈 소견이 5두에서 관찰되었으며, 회복한 환자와 비교할 때 폐사축의 경우 혈소판과 림프구 수가 상대적으로 낮았다.

• Journal of Yeungnam Medical Science
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• 제39권2호
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• pp.124-132
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• 2022

Background: Despite recent advances in first-line chemotherapy for advanced pancreatic cancer, standard treatment after the failure of initial chemotherapy has not been established. Hence, we aimed to retrospectively analyze the clinical characteristics and outcomes of second-line chemotherapy in patients with advanced pancreatic cancer. Methods: We reviewed the clinical data of patients with advanced pancreatic cancer who underwent palliative chemotherapy at Kosin University Gospel Hospital between January 2013 and October 2020. Results: Among 366 patients with advanced pancreatic cancer who had received palliative chemotherapy, 104 (28.4%) underwent at least one cycle of second-line chemotherapy. The median age of the patients at the time of initiating second-line treatment was 62 years (interquartile range, 57-62 years), and 58.7% (61 patients) of them were male. The common second-line chemotherapy regimens were 5-fluorouracil (FU) plus leucovorin, irinotecan, and oxaliplatin (33 patients, 31.7%); gemcitabine/nab-paclitaxel (29, 27.9%), gemcitabine±erlotinib (13, 12.5%); and oxaliplatin and 5-FU/leucovorin (12, 11.5%). The median overall survival (OS) and progression-free survival were 6.4 months (95% confidence interval [CI], 4.5-8.6 months) and 4.5 months (95% CI, 2.7-6.3 months), respectively. In a multivariate analysis, poor performance status (PS) (hazard ratio [HR], 2.247; p=0.021), metastatic disease (HR, 2.745; p=0.011), and elevated carcinoembryonic antigen (CEA) levels (HR, 1.939; p=0.030) at the beginning of second-line chemotherapy were associated with poor OS. Conclusion: The survival outcome of second-line chemotherapy for advanced pancreatic cancer remains poor. However, PS, disease extent (locally advanced or metastatic), and CEA level may help determine patients who could benefit from second-line treatment.

• 중환자간호학회지
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• 제15권3호
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• pp.88-100
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• 2022

Purpose : This study aimed to identify risk factors for unplanned reintubation after planned extubation and to analyze the clinical outcomes in patients admitted to the intensive care unit after cardiac surgery. Methods : The study examined patients who underwent intubation and planned extubation admitted to the intensive care unit after cardiac surgery between January 1, 2017, and December 31, 2021. The reintubation group comprised 58 patients underwent unplanned reintubation within 7 days of planned extubation. The maintenance group comprised 116 patients who did not undergo reintubation and were matched with the reintubation group using the rational for matching criteria. Data were collected retrospectively from electronic medical records. We used the independent t-test, Mann-Whitney U test, 𝑥²-test, Fisher's exact test, and logistic regression analysis with SPSS/WIN 27.0. Results : The multivariate logistic regression analysis demonstrated that albumin (odds ratio [OR]=0.38, 95% confidence interval [CI]=0.20-0.72), surgery time (OR=1.54, 95% CI=1.20-1.97), PaO₂ before extubation (OR=0.85 per 10 mmHg, 95% CI=0.75-0.97), postoperative arrhythmia (OR=2.82, 95% CI=1.22-6.51), reoperation due to bleeding (OR=4.65, 95% CI=1.27-17.07), and postoperative acute renal failure (OR=2.97, 95% CI=1.09-8.04) were risk factors for unplanned reintubation. The reintubation group had a higher in-hospital mortality rate (𝑥²=33.74, p<.001), longer intensive care unit stay (Z=-7.81, p<.001), and longer hospital stay than the maintenance group (Z=-8.29, p<.001). Conclusion : These results identified risk factors and clinical outcomes of unplanned reintubation after planned extubation after cardiac surgery. These findings should be considered when developing and managing an intervention program to prevent and reduce the incidence of unplanned reintubation.

• Advances in pediatric surgery
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• 제17권2호
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• pp.133-138
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• 2011

Extracorporeal membrane oxygenation (ECMO) has been utilized in congenital diaphragmatic hernia (CDH) patients with severe respiratory failure unresponsive to conventional medical treatment. We retrospectively reviewed 12 CDH patients who were treated using ECMO in our center between April 2008 and February 2011. The pre ECMO and on ECMO variables analyzed included gestational age, sex, birth weight, age at the time of ECMO cannulation, arterial blood gas analysis results, CDH location, timing of CDH repair operation, complications and survival. There were 9 boys and 3 girls. All patients were prenatally diagnosed. Mean gestational age was $38.8{\pm}1.7$ weeks and mean birth weight was $3031{\pm}499$ gram. Mean age at the time of ECMO cannulation was $29.9{\pm}28.9$ hours. There were 4 patients who survived. Survivors showed higher 5 min Apgar scores ($8.25{\pm}0.96$ vs. $7.00{\pm}1.20$, p=0.109), higher pre ECMO mean pH ($7.258 {\pm}0.830$ vs. $7.159{\pm}0.986$, p=0.073) and lower pre ECMO $PaCO_2$ ($48.2{\pm}7.9$ vs. $64.8{\pm}16.1$, p=0.109) without statistical significance. The hernia was located on the left side in 10 patients and the right side in 2 patients. The time interval from ECMO placement to operative repair was about 3~4 days in 5 early cases and around 24 in the remaining cases. There were 3 cases of post operative bleeding requiring re operation and 2 cases of abdominal compartment syndrome requiring abdominal fascia reopening. ECMO catheter reposition was required in 4 cases. Three cases of arterial or venous thrombosis were detected and improved with follow up. Our data suggests that ECMO therapy could save the lives of some neonates with CDH who can not be maintained on other treatment modalities. Protocolized management and accumulation of case experience might be valuable in improving outcomes for neonates with CDH treated with ECMO.

• Asian Pacific Journal of Cancer Prevention
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• 제17권4호
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• pp.1759-1767
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• 2016

Background: Uterine sarcoma is a group of rare gynecologic tumors with various natures, and different lines of treatment. Most have a poor treatment outcome. This study targeted clinical characteristics, treatment, overall survival (OS), progression-free survival (PFS), and prognostic factors in uterine sarcoma patients in one tertiary center for cancer care. Materials and Methods: Uterine sarcoma patients who were treated at the Department of Obstetrics and Gynecology, Faculty of Medicine Vajira Hospital between January 1994 and December 2014 were identified. Clinico-pathological data were analyzed. Prognostic outcomes were examined by Kaplan-Meier curves and Cox regression analysis. Results: We identified 46 uterine sarcoma patients: 25 carcinosarcoma (CS) (54.3%), 15 leiomyosarcoma (LMS) (32.6%), and 6 undifferentiated uterine sarcoma (UUS) (13.1%) cases. Mean age was $54.0{\pm}11.9years$ (range 25-82 years). Abnormal uterine bleeding was the most common presenting symptom (63.0%). Among 33 patients (71.7%) who had pre-operative tissue collected, diagnosis of malignancy was correct in 29 (87.9%). All patients received primary surgery and retroperitoneal lymph nodes were resected in 34 (73.9%). After surgery, 5 (10.9%) had gross residual tumors. Stage I disease was most commonly found (56.5%). Adjuvant treatment was given to 27 (58.7%), most commonly chemotherapy. After a median follow-up of 16.0 months (range 0.8-187.4 months), recurrence was encountered in 22 patients (47.8%). Median time to recurrence was 5.8 months (range1.0-105.5 months). Distant metastasis was more common than local or locoregional failure. The 2-year PFS was 45.2% (95% confidence interval [CI], 30.6%-59.7%) and the 2-year OS was 48.3% (95% CI, 33.3%-60.7%). Multivariable analyses found residual disease after surgery as a significant factor only for PFS. Conclusions: Uterine sarcoma is a rare tumor entity. Even with multimodalities of treatment, the prognosis is still poor. Successful cytoreductive surgery is a key factor for a good survival outcome.