• Nuclear Engineering and Technology
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• 제55권8호
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• pp.3017-3029
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• 2023

In the late in-vessel phase of a nuclear reactor severe accident, the internal heat transfer and crust evolution during the debris bed melting process have important effects on the thermal load distribution along the vessel wall, and further affect the reactor pressure vessel (RPV) failure mode and the state of melt during leakage. This study coupled the phase change model and large eddy simulation to investigate the variations of the temperature, melt liquid fraction, crust and heat flux distributions during the debris bed melting process in the hypothetical severe accident of HPR1000. The results indicated that the heat flow towards the vessel wall and upper surface were similar at the beginning stage of debris melting, but the upward heat flow increased significantly as the development of the molten pool. The maximum heat flux towards the vessel wall reached 0.4 MW/m². The thickness of lower crust decreased as the debris melting. It was much thicker at the bottom region with the azimuthal angle below 20° and decreased rapidly at the azimuthal angle around 20-50°. The maximum and minimum thicknesses were 2 and 90 mm, respectively. By contrast, the distribution of upper crust was uniform and reached stable state much earlier than the lower crust, with the thickness of about 10 mm. Moreover, the sensitivity analysis of initial condition indicated that as the decrease of time interval from reactor scram to debris bed dried-out, the maximum debris temperature and melt fraction became larger, the lower crust thickness became thinner, but the upper crust had no significant change. The sensitivity analysis of in-vessel retention (IVR) strategies indicated that the passive and active external reactor vessel cooling (ERVC) had little effect on the internal heat transfer and crust evolution. In the case not considering the internal reactor vessel cooling (IRVC), the upper crust was not obvious.

• 한국컴퓨터정보학회논문지
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• 제14권5호
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• pp.65-75
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• 2009

IT의 발전으로 많은 컴퓨터 사용자들이 인터넷 사용을 생활화하고 있다. HTML 기술을 이용한 웹 기술의 발전은 현대인들의 정보를 빠르고 쉽게 공유할 수 있도록 하고 있으며, 그 이용이 기하급수적으로 증가하고 있는 추세이다. 그러나 그에 따른 부작용으로 중요 시스템에 대한 정보 유출, 전산망 침해 등과 같은 침입 행위 또한 빠른 속도로 증가하고 있다. 이에 본 논문에서 제안하는 공격 트래픽 탐지 기법은 전통적인 네트워크기반 공개 침입탐지시스템인 Snort 탐지한 공격 트래픽 중 false positive 가능성이 있는 패킷을 Nmap 정보를 이용하여 필터링하고, nessus 취약점 정보를 이용하여 2차 필터링을 실시한 후, 운영체제의 적합성, 시그너처 위험도, 보안 취약점을 고려하여 상관성 분석을 최종적으로 실시하여 false positive 경고 메시지를 줄이고 false positive에 의한 오류를 최소화하여 전체적인 공격 탐지 결과를 높였다.

• 한국전기전자재료학회논문지
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• 제36권2호
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• pp.125-128
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• 2023

Recently, as the process of the MOS device becomes more detailed, and the degree of integration thereof increases, many problems such as leakage current due to an increase in electron tunneling due to the thickness of SiO₂ used as a gate oxide have occurred. In order to overcome the limitation of SiO₂, many studies have been conducted on HfO₂ that has a thermodynamic stability with silicon during processing, has a higher dielectric constant than SiO₂, and has an appropriate band gap. In this study, HfO₂, which is attracting attention in various fields, was doped with Al and the change in properties according to its concentration was studied. Al-doped HfO₂ thin film was deposited using Plasma Enhanced Atomic Layer Deposition (PEALD), and the structural and electrical characteristics of the fabricated MIM device were evaluated. The results of this study are expected to make an essential cornerstone in the future field of next-generation semiconductor device materials.

• Journal of Korean Neurosurgical Society
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• 제65권3호
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• pp.479-488
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• 2022

Objective : The surgical management of trigeminal neuralgia (TN) caused by petrous apex meningioma (PAM) is still a challenge because of the lesion's deep location and the surrounding complex structures. The authors describe the intradural anterior transpetrosal approach (ATPA) and its effect on the treatment of TN secondary to PAM. Methods : A retrospective analysis of 15 patients with TN secondary to PAM who underwent surgery via the intradural ATPA was conducted. The key techniques, which included drilling off the petrosal apex (PA) and opening the upper wall of Meckel's cave (MC), are described in detail. Results : Total removal of the tumor and complete pain relief (Barrow Neurological Institute I) were achieved in all 15 patients without significant morbidity. Five patients developed new facial numbness postoperatively, which disappeared within three months after surgery. The postoperative magnetic resonance imaging showed temporal lobe swelling in three patients, but no clinical symptoms. One patient had cerebrospinal fluid leakage and was managed with bed rest and temporary lumbar drainage. One patient had an intracranial infection and was treated with antibiotics. By the last follow up, no patients had pain relapse or/and tumor recurrence. It is worth noting that the vascular compression at the root of the trigeminal nerve was found in one patient during the operation. Conclusion : Our experience suggests that drilling off the PA and opening the upper wall of the MC are key elements for a good outcome of the treatment of TN secondary to PAM. The intradural ATPA has the advantages for both tumor resection and pain relief.

• 대한토목학회논문집
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• 제28권6A호
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• pp.873-880
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• 2008

구조물의 열화 또는 손상상태 점검 시 정기적인 외관조사는 매우 중요한 역할을 담당한다. 이때 실시되는 외관조사는 주로 조사자의 스케치나 일반 카메라를 이용한 사진촬영에 의해 이루어지고 있다. 이럴 경우, 조사에 많은 노력과 시간이 소요된다. 따라서 본 연구에서는 보다 효율적이고 효과적인 조사를 위하여, 터널 외관상의 결함을 자동인식 할 수 있는 시스템을 개발하고자 한다. 이 과정에서 결함 손상인식을 위한 화상처리기술과 데이터 관리 및 분석 시스템이 중점적으로 개발 응용되었다. 이를 통해 콘크리트의 균열, 누수, 백화, 박리, 박락, 손상 등의 결함을 인식하여 데이터를 획득하고, 지속적이고 체계적인 데이터 관리시스템을 구축하여, 터널의 안전성 확보, 기능성 유지, 수명연장 등의 효과를 얻고자 한다.

• Restorative Dentistry and Endodontics
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• 제49권2호
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• pp.20.1-20.13
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• 2024

Objectives: This study investigated the nanoleakage of root canal obturations using calcium silicate-based sealer according to different drying methods. Materials and Methods: Fifty-two extracted mandibular premolars with a single root canal and straight root were selected for this study. After canal preparation with a nickel-titanium rotary file system, the specimens were randomly divided into 4 groups according to canal drying methods (1: complete drying, 2: blot drying/distilled water, 3: blot drying/NaOCl, 4: aspiration only). The root canals were obturated using a single-cone filling technique with a calcium silicate-based sealer. Nanoleakage was evaluated using a nanoflow device after 24 hours, 1 week, and 1 month. Data were collected twice per second at the nanoscale and measured in nanoliters per second. Data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U-tests (p < 0.05). Results: The mean flow rate measured after 24 hours showed the highest value among the time periods in all groups. However, the difference in the flow rate between 1 week and 1 month was not significant. The mean flow rate of the complete drying group was the highest at all time points. After 1 month, the mean flow rate in the blot drying group and the aspiration group was not significantly different. Conclusions: Within the limitations of this study, the canal drying method had a significant effect on leakage and sealing ability in root canal obturations using a calcium silicate-based sealer. Thus, a proper drying procedure is critical in endodontic treatment.

• 경영정보학연구
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• 제18권3호
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• pp.137-153
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• 2016

조직의 비즈니스 환경이 스마트워크와 같이 모바일이나 네트워크에 의존하는 비중이 높아지면서, 기업들은 정보보안에 더 높은 관심을 가지게 되었다. 특히, 내부자의 의한 정보유출은 기업입장에서 상당히 부정적인 영향을 미치게 된다. 따라서 기업뿐 아니라 정보보안 관련 연구자들은 조직원의 정보보안 정책 준수에 초점을 두어 연구를 해왔다. 그 중에서 정보보안 대책(Information security countermeasure)은 조직원의 정보보안 정책 준수 의도의 선행요인으로 알려져 왔다. 하지만 조직원이 정보보안 대책을 인식하도록 하는 선행요인에 대한 연구는 미흡한 실정이다. 본 연구는 조직원의 보안대책 인식에 대한 선행요인으로 경영진의 정보보안 지능을 제안하고 이들의 관계를 실증적으로 연구하였다. 정보보안 지능은 Kirwan(2008)이 제안한 안전지능을 응용하여 정보보안 관련 문제해결능력, 사회적 역량, 정보보안 지식으로 구성된다. 연구결과 경영진의 정보보안 관련 문제해결 능력과 정보보안 지식은 조직원이 정보보안 정책 및 교육/훈련 프로그램을 인식하는데 긍정적인 영향을 미치는 것으로 나타났다.

• 한국재료학회지
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• 제34권8호
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• pp.400-407
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• 2024

The reversible metal electrodeposition (RME) process is used to prepare electrochromic mirrors with reflective-transparent optical states, by depositing metal particles on transparent conductive substrates. These RME based devices can be used in smart windows to regulate indoor temperatures and light levels, serving dual purposes as lighting elements. Commercialization efforts are focused on achieving large-scale production, long-term durability, and a memory effect that maintains coloration without applied voltage. Enhancing durability has received particular attention, leading to the development of electrochromic mirrors that employ gel electrolytes, which are expected to reduce electrolyte leakage and improve mechanical stability compared to traditional liquid electrolyte devices. The gel electrolytes offer the additional advantage of various colors, by controlling the metal particle size and enabling smoother, denser formations. In this study, we investigated improving the durability of RME devices by adding polyvinyl butyral (PVB) to the liquid electrolyte and optimizing the concentration of PVB. Incorporating 10 % PVB resulted in excellent interfacial properties and superior electrochromic stability, with 92.6 % retention after 1,000 cycles.

• Design & Manufacturing
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• 제18권3호
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• pp.71-80
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• 2024

Sink marks are a common defect that occurs due to differences in shrinkage in areas with significant thickness variations in injection-molded parts. In this paper, we investigated the reduction of sink marks and the improvement of gas venting in injection molding processes using External Gas Injection (EGI). A mold was designed with considerations for EGI core pins, O-ring grooves to prevent gas leakage, and ejector-pin sealing. The sink marks were then examined through a series of experiments. When the delay time for injecting compressed air was set to 2.2 seconds, the depth of the sink marks was minimized. However, when the delay time was either too short or too long, the depth of the sink marks increased. There was almost no difference in the depth of the sink marks at discharge pressures of 30 and 50 bar of compressed air, but the sink marks were significantly reduced at a discharge pressure of 70 bar. Under the conditions of a 2.2-second delay time and a supply pressure of 70 bar, the smallest depth, 0.594 ㎛, was observed when the supply time was between 6 and 7 seconds. This represents a reduction of approximately 94% compared to the sink mark depth of 10.078 ㎛ observed with conventional injection molding. To verify the gas venting effect of compressed air injection, an experiment was conducted using non-dried PC. The silver streaks that appeared on the exterior of the molded part were completely eliminated when the air supply pressure was set to 20 bar. This indicates that by injecting compressed air into the mold cavity before injecting the resin, the appearance quality of the injection-molded part can be improved without the need to dry the resin in advance.

• 대한방사선치료학회지
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• 제27권1호
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• pp.87-95
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• 2015

목 적 : 안와 주변 방사선 치료 시 수정체 피폭선량감소를 위하여 사용된 2차 차폐 block의 유용성을 알아보고자 한다. 대상 및 방법 : Human phantom(Alderson Rando Phantom, The Phantom Laboratory, USA)을 사용하여 CT(Somatom Definition AS, Siemens, Germany) 모의촬영 후 전산화치료계획시스템(Pinnacle, PHILIPS, USA)을 통해 실제 치료와 유사한 IMRT치료계획을 실시하였다. 2차 차폐를 위하여 두께 3mm 지름 25 mm의 납판과 3 mm tungsten eye-shield block(Extra small size, Radiation Products Design, Inc, USA)를 사용하였으며, TPS(Treatment Planning System) 상의 lens dose와 모의치료 상의 lens dose를 OSLD로 측정 비교하였다. 또한, 5 cm 두께의 acrylic phantom에 동일한 조건의 2차 차폐물인 3 mm 납판과 tungsten eye-shield block을 사용하여 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$)를 조사 및 측정하였으며, 조사야 밖의 누설선 및 투과방사선 영향을 제한시키고자 8 cm 납블럭(O.S.B: Outside Scatter Block)을 적용하여 위와 동일한 실험을 시행하였다. 조사야로부터 1 cm 이격하여 phantom 끝 옆면에 OSLD(Optically Stimulated Luminescence Dosimeter)를 부착하였고, eyelid의 두께에 해당하는 bolus 3 mm를 적용하였다. 결 과 : human phantom을 이용하여 IMRT 치료계획 상의 Lens dose와 실 측정치는 각각 315.9, 216.7 cGy가 측정되었고, 3 mm 납판과 tungsten eye-shield block으로 2차 차폐 후 각각 234.3, 224.1 cGy가 측정되었다. acrylic phantom을 이용한 실험 결과는 no block, 3 mm 납판, tungsten eye-shield block을 사용했을 때 5.24, 5.42, 5.39 cGy가 측정되었으며, 조사야 밖에 O.S.B를 적용하여 no block, 3 mm 납판, tungsten eye-shield block을 실험한 결과 각각 1.79, 2.00, 2.02 cGy가 측정되었다. 결 론 : 광자선 조사 시 critical organ을 보호하기 위하여 2차 차폐를 적용할 시에는 field 외부일지라도 헤드 누설방사선 및 collimator & MLC 투과방사선이 존재하므로 치료부위와 beam 방향에 따라 금속과 같은 높은 원자번호의 차폐물질이 critical organ근처에 있다면 선량 증가의 원인이 될 수 있다는 사실을 알 수 있었다. 따라서 피폭선량 감소를 위한 2차 차폐의 시도는 분명 의미가 있었으나 미 검증된 시도는 오히려 역효과를 가져올 수 있다는 사실을 인지하여 QA를 통해 목적에 부합하는 결과가 나오는지를 사전에 알아보아야 할 것이다.