• Nuclear Engineering and Technology
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• 제40권2호
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• pp.139-146
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• 2008

This paper presents two of the fuel channel designs being considered for the CANDU-SCWR, a pressure-tube type supercritical water cooled reactor. The first is an insulated pressure tube design. The pressure tube is thermally insulated from the hot coolant by a porous ceramic insulator. Each pressure tube is in direct contact with the moderator, which operates at an average temperature of about $80^{\circ}C$. The low temperature allows zirconium alloys to be used. A perforated metal liner protects the insulator from being damaged by the fuel bundles and erosion by the coolant. The coolant pressure is transmitted through the perforated metal liner and insulator and applied directly to the pressure tube. The second is a re-entrant design. The fuel channel consists of two concentric tubes, and a calandria tube that separates them from the moderator. The coolant enters between the annulus of the two concentric fuel channel tubes, then exits the fuel channel through the inner tube, where the fuel bundles reside. The outer tube bears the coolant pressure and its temperature will be the same as the coolant inlet temperature, ${\sim}350^{\circ}C$. Advantages and disadvantages of these designs and the material requirements are discussed.

• 한국지반공학회논문집
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• 제22권11호
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• pp.55-64
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• 2006

터널과 같은 지하 공동 굴착을 위한 발파로 주변에 손상이 발생하였을 경우, 암반의 역학적 및 수리적 불안정성을 유발하기 때문에 암반의 최종손상영역의 예측은 매우 중요하다 그러나 복잡한 발파거동으로 인해 손상영역을 적절히 예측하는 데에는 상당한 어려움이 따르고 있다. 이러한 어려움을 효과적으로 해결하기 위해 발파하중을 응력파와 가스압으로 분리한 많은 연구가 진행되었다. 응력파는 발파공 주위에 분쇄환(crushing annulus)과 파쇄균열대(fracture zone)를 형성시키며, 상당시간 지속되는 준정적인 가스는 파쇄균열대의 닫힌 균열내부에 침투하여 균열을 다시 진행시키는 역할을 하게 된다. 즉, 가스압은 최종적으로 암반에 손상을 가하는데 기여를 한다. 따라서 본 논문은 이러한 가스압에 의해 생성되는 균열의 최종 진행 길이를 예측함으로써 발파로 인한 최종 손상영역을 간단하게 예측할 수 있는 방법을 제시하고자 한다. 이를 위해 균질한 무한 탄성평면에서 발파공 주위에 대칭으로 형성되는 방사균열을 모델로 사용하였다. 이 모델에서 균열이 진행할 수 있는 조건과 가스의 질량이 일정하다는 두 가지 조건을 사용하였다. 그 결과 응력확대계수는 균열이 진행할수록 감소하여 최종균열의 길이를 산정하였으며, 또한 발파공에 작용하는 압력도 감소하는 것을 확인하였다.

• Annals of Clinical Neurophysiology
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• 제12권1호
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• pp.3-6
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• 2010

The British guideline for early management of persistent low back pain, published in 2009, indicated that physicians should offer exercise or medication, rather than radiological interventions or injections, as first choice of treatment in the patients with chronic low back pain (CLBP). However, there had been great controversies regarding the effectiveness of interventional treatment of patients with CLBP. Both somatic (discogenic, instability, etc) and psychosocial factors contribute to the pathophysiology of chronic low back pain (CLBP). Although it can be difficult in many occasions, thorough interview with the patients and specific diagnostic approaches can help us to identify which is the main etiology in individual patient. With the recent progress in medical radiology and development of new therapeutic modalities, some subgroups of patients of CLBP caused by somatic factors appear to be good candidates of interventional therapy. Interventional therapy can be considered in patients with CLBP caused by annulus rupture, facet joint degeneration, disc degeneration, and vertebral column instability. Among other subgroups of CLBP, carefully selected patients with disc degeneration show the most favorable result by interventional therapy. In this regard, discogenic pain, either as a form of CLBP or acute discogenic radiculopathy, seems to be a good indication of interventional therapy. Because many spine specialists generally consider those with radiculopathy are easier to be treated, patients with CLBP tend to be subjects of conventional conservative therapy. For these reasons, clinicians should make their best effort to identify every possible somatic cause in patients with CLBP before regarding them as hypochondriacs. In this review, some of the recent evidence on the role of interventional treatment in patients with CLBP will be discussed, and some of our cases who showed favorable results by interventional therapy will be presented.

• 한국수산과학회지
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• 제18권3호
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• pp.261-265
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• 1985

한국의 동해 남부 해역에서 1983년 12월에서 1984년 11월까지 채집한 문치가자미를 대상으로 성장${\cdot}$성숙 연령${\cdot}$포란수 및 사망에 대해서 조사하였다. 연륜 형성시의 전장을 보면 암수 각각 $l_{1.2}$가 15.54cm 및 14.78cm, $l_{2.2}$가 20.42cm 및 18.63cm, $l_{3.2}$가 25.10cm 및 21.40cm이고, 암컷의 경우에만 $l_{4.2}$가 29.85cm, $l_{5.2}$가 33.90cm로서 암컷의 성장이 수컷보다 좋았다. 성숙은 암수 모두 만 2세가 되면 절반 이상이 성숙하였고, 성숙 전장은 암컷에서 19.5 cm, 수컷에서 16.5 cm이었다. 성숙란의 포란수는 2세군이 $121{\times}10^3$개, 3세군이 $206{\times}10^3$개, 4세군이 $319{\times}10^3$개, 5세군이 $429{\times}10^3$개이었다. 연간 생잔율은 암컷이 0.435, 수컷이 0.335로 암컷의 수명이 수컷보다 길다.

• Mycobiology
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• 제38권4호
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• pp.249-255
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• 2010

We identified Lacrymaria velutina of the Coprinaceae in Korea. The unusually large and sturdy fruiting body, fibrillose to fibrillose-scaly cap and stalk without a volva with an obscure superior hairy ring zone or hairy annulus, and blackish brown, warted spores distinguished this species from closely related Psathyrella species. An illustrated account of the microscopic traits is presented. Fruiting bodies with obtusely hemispherical caps, 2.5~6 cm, becoming convex with age; surface dry, densely fibrillose-scaly with split margin; stipe, 4.5~6 cm, equal, hollow, fibrillose, dry, whitish above the superior ring zone, light brown below; crowded gills, adnexed, dark black at maturity. Pileipellis typically cellular with the gill edge appearing white and beaded. Blackish brown basidiospores that discolor in concentrated sulfuric acid. Spores elliptical, warted, $9\sim11{\times}6\sim8{\mu}m$, with prominent snout-like germpores. Cheilocystidia abundant, $57\sim68{\times}19\sim25{\mu}m$, and narrowly elongated clavate, often clustered in threes or fours. Pleurocystidia rarely present, $45\sim47.5{\times}12\sim13{\mu}m$, and clavate to utriform. This trait distinguishes our sample as L. velutina from other Psathyrella spp. of the Coprinaceae, which have smooth spores. This taxon was clarified by the observation that Psathyrella spores fade in concentrated sulfuric acid. A molecular phylogenetic study revealed that our specimen was Lacrymria velutipes, which is closely related to Lacrymaria lacrymabunda. Moreover, those two species are clearly distinguishable from other Psathyrella species, which agreed with the morphologically distinctive traits described above. We believe that this is the first report of this taxon, which has not been described in Korea.

• Mycobiology
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• 제47권4호
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• pp.368-377
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• 2019

The genus Macrolepiota (Agaricales, Basidiomycota) is easy to recognize at the genus level because of big, fleshy basidiocarps with squamules covering the pileus; a single or double annulus; and big, thick-walled basidiospores with a germ pore. However, morphological identification is often unreliable in Macrolepiota due to similar morphological features among species. Due to the uncertainty of previous morphological identification in the genus Macrolepiota, it is necessary to re-examine Korean Macrolepiota using molecular data. We reexamined 34 Macrolepiota specimens collected from 2012 to 2018 in Korea using a reverse taxonomic approach, whereby species identification was first done based on the internal transcribed spacer (ITS) region analysis, followed by morphological confirmation. We identified the presence of four species: M. detersa, M. mastoidea, M. procera, and M. umbonata sp. nov. Two species (M. detersa and M. mastoidea) were previously unrecorded from Korea and M. umbonata is a new species. Detailed descriptions of all four species and taxonomic key are provided in this study. Macrolepiota procera and M. umbonata are distributed through the country, but M. detersa and M. mastoidea are distributed only in limited areas. According to our results, the combination of ITS locus and morphology proved to be a robust approach to evaluate the taxonomic status of Macrolepiota species in Korea. Additional surveys are needed to verify the species diversity and clarify their geographic distribution.

• Journal of Chest Surgery
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• 제25권1호
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• pp.32-41
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• 1992

From August 1982 to December 1991, 58 consecutive infants with tetralogy of Fallot underwent primary repair. Age ranged from 22 days to twelve months [n=58, 8.7$\pm$2.7 months] and body weight from 3.1 to 13 kilograms [n=58, 7.8$\pm$1.7 kilograms]. Qne infant had absence of the pulmonary valve; one had Ebstein`s anomaly and one had supramitral ring. Thirty-two patients [56%] experienced anoxic spell. Preoperative pulmonary artery indices were measured in 38 cases, ranging 126-552mm2/M2BSA[n=38, 251$\pm$79mm2/M2BSA]. All infants required a right ventricular outflow tract patch; in 41, the patch extended across the pulmonary valve annulus, in 13 of them, monocusps were constructed. All had patch closure of ventricular septal defect. Two infants had REV operation for avoiding injury to the canal branch of the right coronary artery which cross the right ventricular out flow tract. Post repair PRV/LV were measured at operating room in 40 cases, which revealed mean value of 0.49$\pm$0.12 [range: 0.25-0.74]. The hospital mortality was 10.3% [6 patients], and causes of deaths were right heart failure due to sustained right ventricular hypertension[4] and right ventricular outflow tract obstruction, intractablesuraventricular tachyarrhythmia[1], hypoxia[1] due to residual right to left shunt across the atrial septal defect in patient associated with Ebstein`s anomaly. All infants were doing well at follow-up from 1 to 101 months[20.6 months /patient, 1, 072 patient-month] Serial postoperative echocardiograms revealed no residual ventricular septal defects and estimated RVOT gradients between 0 and 40 mmHg except 3 cases [50, 50, 60 mmHg]. There were no late deaths and late ventricular arrhythmias or congestive heart failure. Redo operations were done in 2 cases because of residual right ventricular outflow tract obstruction. This experience with infants with tetralogy of Fallot suggests that, if mortality is tolerable, eletive repair of tetralogy of Fallot could be reasonably undertaken during the first year of life, and even better results could be anticipated along with improvement of methods of myocardial protection and postoperative care.

• Journal of Chest Surgery
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• 제23권4호
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• pp.617-621
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• 1990

A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

• 터널과지하공간
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• 제32권5호
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• pp.285-297
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• 2022

본 고에서는 한반도 동남권에 분포하는 주요 단층대에 대한 장기 거동 및 미소진동 관찰을 목적으로 하는 시추공 기반 심부 복합지구물리 모니터링 시스템 구축의 일환으로 수행된 대구경 시추공 굴착 현장에서 이루어진 Extended Leak-Off Test (XLOT)에 대한 내용 및 결과를 보고한다. 다양한 시추공 센서 설치를 위한 모니터링공의 굴착은 ~1 km 깊이에서 최종 구경 200 mm 이상을 확보하는 것을 목표로 하여, 중간 깊이까지 12" 구경의 시추공 굴진 및 케이싱 설치, 이후 최종 심도까지 7-7/8" 구경의 시추공을 굴진하는 것으로 설계되었다. 현장 여건에 맞추어 약 504 m 깊이까지 12" 구경의 시추공이 굴착되었으며, API 규격의 8-5/8" 케이싱을 설치하고 배면과 암반 간의 틈새(annulus)에 대한 세멘팅 작업을 수행하였다. 이후 하부 구간 굴진(7-7/8")에 앞서 세멘팅 건정성 확인 및 암반 응력 측정 등을 목적으로 XLOT를 수행하였다. 약 4 m 길이의 나공 구간(open hole)을 확보하고, 상부에 설치된 케이싱을 이용해 물을 주입하여 시험 심도의 암반을 가압하였다. XLOT 수행 과정에서 주입 유량에 따른 시험 구간 내 압력 변화 양상을 실시간 모니터링 하였으며, 이 자료들을 일부 활용하여 현장 시추공 조건에서의 암반 투수율을 해석하였다.

• 한국수학교육학회지시리즈A:수학교육
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• 제59권2호
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• pp.131-146
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• 2020

원의 넓이를 구하는 공식을 보면, 일반적으로 원주율이 반지름의 길이의 제곱의 앞에 쓰여 지지만 독일과 프랑스에서 원주율이 뒤에 쓰여 진 경우가 있었다. 본 연구에서는 두 가지를 연구 한다: 첫째, 원주율을 뒤에 쓰는 학생이 얼마나 있는가? 둘째, 학생들이 원의 넓이를 구하는 공식에서 문자 표기 순서에 대해 어떻게 인식하는가? 국내의 만 14세에서 만 21세까지의 사람들 중 임의 추출한 201명에 대한 온라인 설문 조사 결과 둘 다 가능하다 또는 뒤에만 가능하다는 인식이 86% 이상 있었다. 본 연구에는 원의 넓이에 대한 일반적인 문자 표기 순서와 학교 교육을 통해 자연스럽게 형성된 학생들의 인식에 차이가 있음이 보여 진다. 덧붙여 만 14세에서 만 16세까지의 학생들은 원주율을 뒤에만 써야한다는 인식이 더 강했으나 그 연령대 이후로 둘 다 가능하다는 인식의 변화가 있었다. 이러한 관점에서 의미의 혼동이 없다면, 두 표기 모두 가능하다는 것이 가장 공통적인 인식이 될 수 있다. 그러므로 교과서에는 원주율을 뒤에 쓴 표현이 추가된 방식으로 표현되어야 학생들의 이해가 더 자연스러울 것이다.