• 해양환경안전학회지
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• 제12권1호
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• pp.33-38
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• 2006

해난사고 선박의 구난환경 위험성 분석을 위한 극치조석 산정을 연구하였다. 본 연구에서는 표준항에서 관측된 해면변위에서 주요 4대분조($M_2$조, $S_2$조, $K_1$조, $O_1$조)의 진폭과 극치조석의 진폭을 산정하고, 조석 공간분포의 균일성에 근거한 유추(inference)방법을 이용하여 둘 간의 상관관계를 수치모델로 계산된 주요 4대분조의 공간분포에 적용함으로써 극치조석의 공간분포를 산정하였다. 극치조석의 분포는 한국 남해를 대상으로 산정하였으며, 50년 주기와 100년 주기의 극치조석을 각각 산정하였다. 한국 남해의 50년 주기 극치조석 진폭은 $70cm{\sim}260cm$의 분포를 보였으며, 100년 주기 극치조석 진폭은 $80cm{\sim}270cm$의 분포를 보였다. 극치조류의 유속은 100년 주기의 경우 평균상태 조류 유속에 비하여 약 1.55배 강한 것으로 나타났다.

• 한국산학기술학회논문지
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• 제20권7호
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• pp.599-606
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• 2019

위험물질에 의한 제조물을 취급하는 설비와 시설은 대부분 고온, 고압으로 공정을 운전을 한다. 이로 인해 화재폭발로 인한 위험성이 증대되고 있다. 특히, 폭발 사고는 석유 화학 가스설비 등 위험물 시설의 가장 주된 위험요인으로 작용하고 있으며, 그 중, 프로필렌은 석유화학 플랜트의 기초 원료 및 첨가 중합반응에 의한 합성물질을 제조하는 현장에서 많이 사용되고 있다. 산소농도의 변화에 대한 폭발범위를 구함으로써 프로필렌을 사용하는 사업장에서 발생 될 수 있는 폭발을 예방하기 위하여 불활성 가스인 $CO_2$를 이용하여 온도와 압력의 변화에 따라 산소농도의 변화에 대한 폭발범위를 구하였다. 온도는 $25^{\circ}C$, $100^{\circ}C$, $200^{\circ}C$로 변화시켜 측정하였으며, 용기 내 압력을 $1.0kgf/cm^2.G$, $1.5kgf/cm^2.G$, $2.0kgf/cm^2.G$, $2.5kgf/cm^2.G$로 $CO_2$를 가압시켜 측정하였다. 폭발한계는 온도, 압력 및 산소농도와 관계가 있으며, 온도와 압력이 높아질수록 최소산소농도는 낮아지고, 산소농도가 낮아질수록 폭발범위는 좁아졌다. 또한, 최소산소농도 이하의 농도에서는 프로필렌의 증기와 점화원이 존재하여도 폭발이 발생하지 않는 것을 알 수 있다.

• 한국도로학회논문집
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• 제19권5호
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• pp.59-68
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• 2017

PURPOSES : The objective of this study is to evaluate the potential risk level of road cave-ins due to subsurface cavities based on the deflection basin measured with falling weight deflectometer (FWD) tests. METHODS: Ground penetrating radar (GPR) tests were conducted to detect road cavities. Then FWD tests were conducted on 13 pavement test sections with and without a cavity. FWD deflections and a deflection ratio was used to evaluate the effect of geometry of the cavity and pavement for road cave-in potentials. RESULTS : FWD deflection of cavity sections measured at 60 cm or a closer offset distance to a loading center were 50% greater than more robust sections. The average deflection ratio of the cavity sections to robust sections were 1.78 for high risk level cavities, 1.51 for medium risk level cavities, and 1.16 for low risk level cavities. The relative remaining service life of pavement with a cavity evaluated with an surface curvature index (SCI) was 8.1% for the high level, 21.8% for the medium level, and 89.8% compared to pavement without a cavity. CONCLUSIONS : FWD tests can be applied to detect a subsurface cavity by comparing FWD deflections with and without a cavity measured at 60 cm or a closer offset distance to loading center. In addition, the relative remaining service life of cavity sections based on the SCI can used to evaluate road cave-in potentials.

• 한국방사선학회논문지
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• 제16권7호
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• pp.843-849
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• 2022

본 연구에서는 감마나이프를 이용한 방사선 수술 시 주변 정상 장기들의 피폭선량을 측정하여 2차 발암확률을 분석하고자 한다. 인체 조직 등가 물질로 구성된 소아 팬텀(Model 706-G, CIRS, USA)에 종양 볼륨은 0.25 cm³, 0.51 cm³, 1.01 cm³, 2.03 cm³ 총 4개로 설정하였으며, 평균 선량은 18.4 ± 3.4 Gy로 하였다. 감마나이프 수술 장비의 테이블위에 Rando phantom을 설치한 후에 OSLD nanoDot 선량계를 Right eye, Left eye, Thyroid, Thymus gland, Right lung, Left lung 에 위치시켜 각각의 피폭선량을 측정하였다. 청신경초종질환의 감마나이프 방사선 수술 시 주변 정상 장기들의 방사선 피폭으로 인한 암 발생확률은 종양 볼륨 2. 03 cm³에서 100,000명 당 4.08명의 암이 발생함을 알 수 있다. 본 연구는 정위적 방사선 수술 시 발생할 수 있는 2차 방사선 피폭선량의 위험성을 연구하여 향후 확률적 영향과 관련하여 유용한 자료로 활용될 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.165-169
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• 2018

An assessment for determining N-16 activity concentrations during the operation condition of Bangladesh Atomic Energy Commission TRIGA Research Reactor was performed employing several governing equations. The radionuclide N-16 is a high energy (6.13 MeV) gamma emitter which is predominately created by the fast neutron interaction with O-16 present in the reactor core water. During reactor operation at different power level, the concentration of N-16 at the reactor bay region may increase causing radiation risk to the reactor operating personnel or the general public. Concerning the safety of the research reactor, the present study deals with the estimation of N-16 activity concentrations in the regions of reactor core, reactor tank, and reactor bay at different reactor power levels under natural convection cooling mode. The estimated N-16 activity concentration values with 500 kW reactor power at the reactor core region was $7.40{\times}10^5Bq/cm^3$ and at the bay region was $3.39{\times}10^5Bq/cm^3$. At 3 MW reactor power with active forced convection cooling mode, the N-16 activity concentration in the decay tank exit water was also determined, and the value was $4.14{\times}10^{-1}Bq/cm^3$.

• 한국운동역학회지
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• 제32권1호
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• pp.9-16
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• 2022

Objective: The purpose of this study was to investigate how the chronic ankle instability affects postural control during forward jump landing. Method: 20 women with chronic ankle instability (age: 21.7 ± 1.6 yrs, height: 162.1 ± 3.7 cm, weight: 52.2 ± 5.8 kg) and 20 healthy adult women (age: 21.8 ± 1.6 yrs, height: 161.9 ± 4.4 cm, weight: 52.9 ± 7.2 kg) participated in this study. For the forward jump participants were instructed to stand on two legs at a distance of 40% of their body height from the center of force plate. Participants were jump forward over a 15 cm hurdle to the force plate and land on their non-dominant or affected leg. Kinetic and kinematic data were obtained using 8 motion capture cameras and 1 force plates and joint angle, vertical ground reaction force and center of pressure. All statistical analyses were using SPSS 25.0 program. The differences in variables between the two groups were compared through an independent sample t-test, and the significance level was to p < .05. Results: In the hip and knee joint angle, the CAI group showed a smaller flexion angle than the control group, and the knee joint valgus angle was significantly larger. In the case of ankle joint, the CAI group showed a large inversion angle at all events. In the kinetic variables, the vGRF was significantly greater in the CAI group than control group at IC and mGRF. In COP Y, the CAI group showed a lateral shifted center of pressure. Conclusion: Our results indicated that chronic ankle instability decreases the flexion angle of the hip and knee joint, increases the valgus angle of the knee joint, and increases the inversion angle of the ankle joint during landing. In addition, an increase in the maximum vertical ground reaction force and a lateral shifted center of pressure were observed. This suggests that chronic ankle instability increases the risk of non-contact knee injury as well as the risk of lateral ankle sprain during forward jump landing.

• Journal of Nutrition and Health
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• 제39권7호
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• pp.684-691
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• 2006

Abdominal obesity (AO) is a strong risk factor for type 2 diabetes and cardiovascular disease, which has shown a remarkable increase in Korea. This study aimed to identify prevalence of AO and related risk factors in Korean adults. A total of 5,132 men and women aged 20-85 years old from the 2001 Korean National Health and Nutrition Examination Survey were included in the analyses. AO was defined as waist circumference >=90 cm in men and >=85 cm in women as proposed by Korean Society of Obesity. Multiple logistic regression was carried out to identify risk factors for AO. Three models were specified: (i) demographic and socioeconomic factors (model 1: age, education, poverty income ratio, employment), (ii) lifestyle factors and covariates (model 2: physical activity, cigarette smoking, alcohol consumption, dietary quality, type 2 diabetes, co-morbidity) and (iii) demographic, socioeconomic and lifestyle factors (model 3). The prevalence of AO was 24.1 % in men, 23.5% in women. High poverty income ratio in men and low education attainment in women were risk factors for AO in model. 1. There was a significant association of AO with alcohol consumption, physical inactivity and dietary quality in men, alcohol consumption and cigarette smoking in women. These factors except alcohol consumption in men became insignificant in model 3. This findings underscore the importance of developing AO prevention programs in Korea that target the at risk groups identified in this study. A program focusing on low income men or less educated women would be more efficient.

• Journal of Chest Surgery
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• 제57권2호
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• pp.136-144
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• 2024

Background: Early non-small cell lung cancer (NSCLC) that abuts adjacent structures requires careful evaluation due to its potential impact on postoperative outcomes and prognosis. We examined stage I NSCLC with invasion into adjacent structures, focusing on the prognostic implications after curative surgical resection. Methods: We retrospectively analyzed the records of 796 patients who underwent curative surgical resection for pathologic stage IA/IB NSCLC (i.e., visceral pleural invasion only) at a single center from 2008 to 2017. Patients were classified based on tumor abutment and then reclassified by the presence of visceral pleural invasion. Clinical characteristics, pathological features, and survival rates were compared. Results: The study included 181 patients with abutting NSCLC (22.7% of all participants) and 615 with non-abutting tumors (77.3%). Those with tumor abutment exhibited higher rates of non-adenocarcinoma (26.5% vs. 9.9%, p<0.01) and visceral/lymphatic/vascular invasion (30.4%/33.1%/12.7% vs. 8.5%/22.4%/5.7%, respectively; p<0.01) compared to those without abutment. Multivariable analysis identified lymphatic invasion and male sex as risk factors for overall survival (OS) and disease-free survival (DFS) in stage I NSCLC measuring 3 cm or smaller. Age, smoking history, vascular invasion, and recurrence emerged as risk factors for OS, whereas the presence of non-pure ground-glass opacity was a risk factor for DFS. Conclusion: NSCLC lesions 3 cm or smaller that abut adjacent structures present higher rates of various risk factors than non-abutting lesions, necessitating evaluation of tumor invasion into adjacent structures and lymph node metastasis. In isolation, however, the presence of tumor abutment without visceral pleural invasion does not constitute a risk factor.

• 한국방사선학회논문지
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• 제8권7호
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• pp.449-454
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• 2014

이 연구의 목적은 6 MV 광자 빔에 대하여 팬텀 표면으로부터 1 cm 깊이에서 조사야 가장자리 바깥 축외선량비와 1 mmPb의 차폐비를 조사하는 데 있다. 180 cGy의 선량은 SAD기법에서 $10{\times}10cm^2$와 $15{\times}15cm^2$ 조사야에 대하여 깊이 10 cm에 전달되었다. 축외선량비는 조사야의 중심축과 가장자리로부터 2, 4, 6 cm에 위치된 광자극형광나노닷선량계(OSLnD)들의 선량을 측정하여 계산하였다. 그리고 1 mmPb의 차폐비는 조사야 가장자리로부터 2, 4, 6 cm에 위치된 OSLnD들의 선량을 측정하여 산출하였다. 결과로서, $10{\times}10cm^2$와 $15{\times}15cm^2$ 조사야에 대하여, 축외선량비들은 0.008-0.023과 0.011-0.028을 각각 얻었다. 또한 1 mmPb의 차폐비들은 0.868-0.888과 0.807-0.842을 각각 얻었다. 이 결과들은 방사선치료 조사야 바깥에 위치한 위험장기들을 보호하기 위한 자료를 제공한다.

• Environmental Analysis Health and Toxicology
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• 제22권4호
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• pp.339-348
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• 2007

A laboratory experiment was conducted to study the characteristics of leaching of Cr, Cu, and As from chromated topper arsenate (CCA)-treated wood. The wood species tested was hemlock spruce ($10\;cm\;{\times}\;10\;cm\;{\times}\;10\;cm\;tube$). The leaching experiment was conducted over 60 days using I L of leachants whose pHs were adjusted to 2.0, 3.7, and 1.6, respectively with nitric acid, and also using lake water, according to the OECD guideline. Each leachate was analyzed for Cr and Cu using flame-AAS, and for As using vapor generation-AAS. Three metals were loathed at the highest levels at pH 2.0 but almost at similar levels at the other conditions. Cumulative quantifies over 60 days of a leaching period were in order of As>Cu>Cr. As was predicted to leach with an increase in flux over a 10 year period, while Cr and Cu fluxes were predicted to decrease with time. This result suggest that arsenic can pose a health risk to humans over a long period of time, when CCA-treated wood is used for building facilities (e.g., playgrounds, residential purposes, etc.) with which humans frequently contact.