• Journal of Astronomy and Space Sciences
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• 제26권2호
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• pp.237-266
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• 2009

1631년에 명(明)에 사신으로 다녀오던 정두원은 산둥(산동(山東)) 반도의 덩저우(등주(登州))에서 예수회 선교사인 조앙 로드리게스를 만났다. 로드리게스는 정두원에게 많은 다수의 서양 문물을 전해주었다. 정두원의 "서양국기별장계(西洋國奇別狀啓)"는 이 사건을 이해하는데 중요한 사료이다. 이 문헌은 고전 한문으로 되어 있으므로, 이 논문에서는 현대 한국어로 역주를 하였고, 그 과정에서 이전 연구자들이 오해한 여러 가지 사실들을 바로 잡았다. 이 문헌에 따르면, 정두원이 받아온 것은, 중국어로 저술된 서양 서적 네 권, 명(明) 조정에 홍이포(紅夷砲)를 바친 경위에 대한 보고서, 망원경, 수발총, 폴리오트식 기계 시계, 마테오 리치가 그린 세계지도, 천문도, 해시계 등이었다. 우리는 이 물품들이 한국 과학기술사 속에서 어떤 의미를 갖는지 논의한다. 특히 정두원의 서양 문물 전래는 한국 천문학사에서도 중요한데, 왜냐하면 그가 가져온 망원경이 한국사상 최초의 망원경이었기 때문이다. 당시 조선의 임금과 관리들은 망원경, 홍이포, 신식 조총과 같은 새로운 기술들이 군사적으로 유용함을 잘 알고 있었으나, 그럼에도 불구하고 결과적으로 이를 재빨리 수용하여 국방력을 강화하지 못했다. 우리는 당시 동아시아 과학기술사의 일반적인 역사에 비추어 보아 그 까닭을 재고해보려한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1478-1480
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• 1997

We investigated the breakdown characteristic of mineral oil according to applied voltage and tip radius. In this experiment, electrode system was point-plane geometry. The tip radius of needle was 5, 10, 20 and $25{\mu}m$, respectively. Applied voltage was AC and DC. We measured breakdown voltage for each tip radius with increasing electrode gap, 2mm to 10mm. Under nonuniform electric field, breakdown strength was higher when needle was negative than when needle was positive. Because it is polarity effects due to space charge. And the more sharp tip radius, whether we applied AC or DC, the higher breakdown strength. As tip radius increase, breakdown strength decreases exponentially.

• 한국가시화정보학회지
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• 제17권2호
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• pp.32-38
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• 2019

A comparison study between computational-fluid-dynamics simulation and wind tunnel test for a megawatt-class wind turbine is conducted. For the study, flow-field in wake, basic aerodynamic performance, and effect of the yaw error for a 1/86 scaled-down model of the NREL offshore 5 MW wind turbine are numerically calculated using commercial software "FloEFD" with $k-{\varepsilon}$ turbulence model. The computed results are compared to the wind tunnel test performed by the constant-velocity mode for the model. It is shown that discrepancy are found between the two results at lower tip-speed ratio and higher yaw angle, however, the velocity-defection distribution in the wake, the torque coefficient at moderated and high tip-speed ratios are in good agreement with the wind tunnel test.

• Journal of Oral Medicine and Pain
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• 제41권4호
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• pp.200-204
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• 2016

Numb chin syndrome, or mental neuropathy is a rare sensory neuropathy characterized by abnormal sensation such as hypoesthesia, paresthesia, or dysesthesia in the chin and lower lip innervated by the mental nerve. Sensory neuropathy of mental nerve is somewhat familiar to dentists because it can occur following nerve damage by trauma or dental treatment such as implant surgery or third molar extraction. It can also result from dental causes including abscess or osteomyelitis. However, it can be the first sign of the systemic disease or malignancy if it is not related to dental causes. In this study, we present the case of a patient who present with hypoesthesia and pain in chin area without other symptoms and is later diagnosed with diffuse large B-cell lymphoma.

• Journal of Oral Medicine and Pain
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• 제41권2호
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• pp.72-75
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• 2016

Lichen planus is a chronic disease characterized by bilateral and multiple lesions on the skin or oral mucosa. Lichen planus is caused by immune mediated degeneration along the border between epithelium and connective tissue. The incidence of oral squamous cell carcinoma in patients diagnosed with oral lichen planus (OLP) is reported to be between 0.4%-5.6% in different studies and the World Health Organization has categorized lichen planus as "a potentially malignant disorder". However, the correlation between OLP and oral cancer still remains controversial as some reported that the reason for increased incidence of squamous cell carcinoma in OLP patient is misdiagnosis of dysplastic lesion as OLP. This report aims to discuss the correlation between OLP and oral cancer through a case of middle aged woman diagnosed with OLP who was successfully treated but developed squamous cell carcinoma 8 years later.