• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1674-1685
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• 2022

The ball valve is an important device in the pipeline transportation system of nuclear power plants. Its operational stability and safety directly affect the normal working of nuclear power plants. In this study, the transient numerical simulation of the opening and closing process of a ball valve was conducted on the basis of the flow interruption capability experiment of the ball valve by using the moving mesh method and inlet and outlet variable boundary conditions. The flow rate and pressure difference with time of the opening and closing process of the ball valve were studied. The internal flow characteristics of the ball valve under different relative openings were analyzed in conjunction with the typical back-step flow structure. Results show that the transient numerical results agree well with the experimental results. The internal flow characteristics of the ball valve are similar at the same opening during opening and closing process. At small opening, the spool and outlet channels easily form a back-step flow structure. The disappearance and generation of backflow vortices during opening and closing occur at 85% opening and 75% opening, respectively. With the decrease in opening degree, the difference in vortex core area in the flow channel of the ball valve spool in the opening and closing process gradually appears. The research results provide some reference value for the design and optimization of ball valves.

• 한국항만경제학회지
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• 제37권3호
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• pp.75-91
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• 2021

최근 제4차산업 혁명의 적용으로 물류비 절감을 위한 공급사슬 측면의 경쟁이 더욱 치열해지면서 항만전문가들은 효율적인 항만운영 비즈니스모델을 개발에 관심이 집중되어 있다. 본 연구는 세계 여러 항만 중 미국 항만 물류량이 많은 항만을 분석하여 적용 모델을 구성하고자 한다. 본 연구는 주로 미국 항만의 생산성을 연구하기 위해 DEA(Data Enclapment Analysis) 기법을 사용하였으며 미국 항만 운영의 성장 동력을 추가 조사하기 위해 Simar & Wilson(2007)이 제안한 이중 부트스트래핑 DEA 알고리즘을 적용했다. 본 연구에 사용된 외부 변수는 항만의 길이, 항만의 심도, 위치, 면적, 에이커, 외화 비율 및 TEUChange에 포함되며, 이 중 항만의 길이, 에이커, 외화 비율 및 TEUChange에 유의했다. 최적 방법론 선택의 효과를 평가하기 위해 관측 중단 모형(Tobit)을 적용하여 동일한 분석을 수행하고 서로 다른 두 기법에서 도출된 결과를 대조하였다. 본 연구에서 얻은 결과를 바탕으로 경영상의 시사점을 제안하고 결론을 도출하였다.

• Ecology and Resilient Infrastructure
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• 제9권4호
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• pp.247-258
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• 2022

함평만은 좁은 만 입구와 복잡한 지형 구조로 인하여 비대칭적인 퇴적물 이동이 일어나기 때문에, 갯벌의 저질에는 모래 함량이 증가하는 것으로 연구되었다. 모래화 갯벌은 염습지 식생 분포를 변화시키는 것으로 현존식생도와 식생단면도 조사를 통해 분석되었다. 2016년과 2022년의 식생면적 비교에서 절대염생식물인 해홍나물군락은 74% 감소하였다. 반면 임의염생식물인 갯잔디군락은 75% 증가하였다. 특히 갯잔디는 지하경과 줄기의 밀도가 높게 발달하여, 군락 내 모래와 같은 퇴적물을 가둬서 견고한 사구환경을 조성하는 것으로 보인다. 함평만 갯벌의 효과적인 자연보전 관리 계획 수립을 위하여, 갯벌 토성 변화와 식생 군집의 상호작용이 향후 갯벌생태계에 미치는 영향에 대해 통합적 접근이 필요하다.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.1062-1070
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• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• 패션비즈니스
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• 제26권4호
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• pp.64-82
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• 2022

This study aimed to explore fashion technologies for small-scale designer brands and reveal the priorities of the derived fashion technologies. Interviews were conducted with owners of 15 designer brands to explore fashion technologies needed in the field based on the business operation stage (study 1), and an online survey of owners of 61 designer brands was conducted to verify their priorities (study 2). A total of 12 fashion technologies were derived from study 1, including 2 market analysis stages, 6 season planning stages, and 4 product operation stages. In study 2, importance and satisfaction were measured with 12 fashion techniques derived from study 1, and importance-performance analysis (IPA) was performed. The technologies of product management with image tagging and sales channel matching were considered to be the fashion technologies that should be developed first. Second, in the case of maintenance, demand prediction and price determination were applicable. Third, over-effort avoidance was revealed through market analysis and design generation. Finally, in automatic product detail page creation and digital marketing, development was the lowest priority. The results of this study are expected to provide insight into priority areas for fashion technology developers and policy departments providing emerging brand support.

• 한국응용과학기술학회지
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• 제39권3호
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• pp.433-441
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• 2022

MCN 스포츠 중계의 미디어 인게이지먼트, 미디어 공감, 그리고 미디어 가치와의 관계를 규명하기 위한 이 연구는 MCN 스포츠 중계 시청 경험을 가진 시청자 총 324명을 대상으로 비확률 표본 표집 중에서 목적 표집법을 통해 설문조사를 실시하였다. 탐색적 요인분석을 실시하여 타당도를 확인하였으며, Cronbach's α 검사를 실시하여 신뢰도를 조사하였다. 또한 상관관계분석을 실시하여 판별타당도를 검증하였으며, 연구가설을 검증하기 위해 선형 회귀분석을 실시하여 다음과 같은 결론을 도출하였다. 첫째, MCN 스포츠방송과 관련하여 미디어 인게이지먼트가 미디어 가치에 긍정적인 영향을 미치는 것으로 나타났다. 둘째, 미디어 인게이지먼트가 미디어 공감에 긍정적인 영향을 미치는 것으로 나타났다. 셋째, 미디어 공감이 미디어 가치에 긍정적인 영향을 미치는 것으로 나타났다.

• The Korean Journal of Physiology and Pharmacology
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• 제27권1호
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• pp.39-48
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• 2023

Spinal nerve injury causes mechanical allodynia and structural imbalance of neurotransmission, which were typically associated with calcium overload. Storeoperated calcium entry (SOCE) is considered crucial elements-mediating intracellular calcium homeostasis, ion channel activity, and synaptic plasticity. However, the underlying mechanism of SOCE in mediating neuronal transmitter release and synaptic transmission remains ambiguous in neuropathic pain. Neuropathic rats were operated by spinal nerve ligations. Neurotransmissions were assessed by whole-cell recording in substantia gelatinosa. Immunofluorescence staining of STIM1 with neuronal and glial biomarkers in the spinal dorsal horn. The endoplasmic reticulum stress level was estimated from qRT-PCR. Intrathecal injection of SOCE antagonist SKF96365 dose-dependently alleviated mechanical allodynia in ipsilateral hind paws of neuropathic rats with ED₅₀ of 18 ㎍. Immunofluorescence staining demonstrated that STIM1 was specifically and significantly expressed in neurons but not astrocytes and microglia in the spinal dorsal horn. Bath application of SKF96365 inhibited enhanced miniature excitatory postsynaptic currents in a dosage-dependent manner without affecting miniature inhibitory postsynaptic currents. Mal-adaption of SOCE was commonly related to endoplasmic reticulum (ER) stress in the central nervous system. SKF96365 markedly suppressed ER stress levels by alleviating mRNA expression of C/ EBP homologous protein and heat shock protein 70 in neuropathic rats. Our findings suggested that nerve injury might promote SOCE-mediated calcium levels, resulting in long-term imbalance of spinal synaptic transmission and behavioral sensitization, SKF96365 produces antinociception by alleviating glutamatergic transmission and ER stress. This work demonstrated the involvement of SOCE in neuropathic pain, implying that SOCE might be a potential target for pain management.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• 제55권8호
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• pp.498-507
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• 2012

Background and Objectives We aimed to develop a Korean version of the velopharyngeal insufficiency (VPI) speech corpus system. Subjects and Method After developing a 3-channel simultaneous speech recording device capable of recording nasal/oral and normal compound speech separately, voice data were collected from VPI patients aged more than 10 years with/without the history of operation or prior speech therapy. This was compared to a control group for which VPI was simulated by using a french-3 nelaton tube inserted via both nostril through nasopharynx and pulling the soft palate anteriorly in varying degrees. The study consisted of three transcriptors: a speech therapist transcribed the voice file into text, a second transcriptor graded speech intelligibility and severity and the third tagged the types and onset times of misarticulation. The database were composed of three main tables regarding (1) speaker's demographics, (2) condition of the recording system and (3) transcripts. All of these were interfaced with the Praat voice analysis program, which enables the user to extract exact transcribed phrases for analysis. Results In the simulated VPI group, the higher the severity of VPI, the higher the nasalance score was obtained. In addition, we could verify the vocal energy that characterizes hypernasality and compensation in nasal/oral and compound sounds spoken by VPI patients as opposed to that characgerizes the normal control group. Conclusion With the Korean version of VPI speech corpus system, patients' common difficulties and speech tendencies in articulation can be objectively evaluated. Comparing these data with those of the normal voice, mispronunciation and dysarticulation of patients with VPI can be corrected.

• 한국압력기기공학회 논문집
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• 제18권2호
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• pp.37-42
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• 2022

An influence analysis on multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout is performed to compare the plant responses according to the number of ruptured u-tubes under the assumption of a total of 10 ruptured u-tubes. In all calculation cases, the transient behaviour of major thermal-hydraulic parameters, such as the discharge flow rate through the ruptured u-tubes, reactor header pressure, and void fraction in the fuel channels is found to be overall similar to that of the base case having a single SG with 10 u-tubes ruptured. Additionally, as the conditions of low-flow coolant with high void fraction in the broken loop continued, causing the degradation of decay heat removal, the peak cladding temperature (PCT) would be expected to exceed the limit criteria for ensuring nuclear fuel integrity. However, despite the same total number of ruptured u-tubes, because of the different connection configuration between the SG and pressurizer, a difference is foud in time between the pressurizer low-level signal and reactor header low-pressure signal, affecting the time to trip the reactor and to reach the PCT limit. The present study is expected to provide the technical basis for the accident management strategy for mSGTR transient conditions of CANDU-6 plants.

• 대한토목학회논문집
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• 제30권6B호
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• pp.533-540
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• 2010

최근, 하천변에 분포된 식생관리는 하천의 안정성 뿐만 아니라 하천복원을 위해서도 매우 중요하다. 통상 하천변에 분포된 식생에 의하여 수리학적 저항이 증가되고 통수능이 감소되어 제방 범람을 초래한다. 본 논문에서는 1차원 및 2차원 수리해석 모형을 활용하여 소양강 댐 하류하천을 대상으로 서로 상이한 식생분포에 해당하는 조도계수를 적용함으로써 식생에 의한 제방월류 가능성을 검토하였다. 본 연구에서는 3가지 상이한 조도계수 즉, 관목부, 교목부, 그리고 주수로 부로 구분하여 해당되는 조도계수를 현장측정을 통해 작성한 식생도를 바탕으로 모형에 반영하여 이들에 의한 영향을 고려하였다. 전체적으로 식생에 의하여 약 0.1 m - 0.7 m 수위가 상승하는 것으로 모의되었으며 월류에 취약한 제방의 경우 범람방지를 위해 적절한 대책이 필요한 것으로 분석되었다.