• 한국해양학회지
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• 제9권1_2호
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• pp.52-58
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• 1974

한국동안의 해수의 물리의 특성 및 해수의 운동에 관하여는 오래 전부터 많은 연구가 행하여졌다. Nishida(1927)에 의하면, 대한해협을 통과한 Tsushima난류는 다시 세 지류로 나뉘어 지며 첫째가 한국동안을 따라 북상하는 북상류, 둘째로 울릉도를 지나는 북동류, 셋째는 일본 북안을 끼고 흐르는 Tsushima본류라 하였다. 또한 그 (1926)의 관측에 의하면 대한해협의 서측북안 즉 한국 남동안 근처에서 수년 주기로 냉수의 표면노출 현상이 나타나고 있으며, 남서향하는 저층냉수의 속도는 0.1-0.35 knot에 이르고 있다. 임과 장(1969)은 대한해협 서측의 남서향 하는 저층수를 냉수괴라 하여 3-1$0^{\circ}C$로 규정하고 있으며, 이러한 저층냉수는 동해에서 생성된 수괴로 여름철에 해저를 따라 남서 방향으로 흘러 나가기 시작한다 하였다. 임(1973)은 대한해협의 저층냉수에 대한 연구에서, 6월에 대한해협을 통과하는 저층냉수 양을 17,135㎥/sec로 추산하였다. 수괴에 대하여는 임(1971)이 대한해협을 통과하는 Tsushima난류의 수괴에 대하여, Abe와 Myazaki(1960), 그리고 Uda에 의하여 동해의 수괴가 연구되었다. 임은 Tsushima난수를 Kuroshio의 표면수와 동지나 연안수의 혼합체라 하였다. Abe와 Myazaki, 그리고 Uda에 의하면, 동해에는 동해중간수(Mid- Water)와 그 밑으로 동해고유수(Japan Sea Proper Water)가 존재하며, 북한한류(North Korea Cold Current)와 Tsushima난류의 극전선 형성으로, 한류를 형성하고 있는 냉수괴가 침강하여 이것이 Tsushima난수의 밑에 존재하게 된다 하였다.

• 한국방사선학회논문지
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• 제12권3호
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• pp.335-341
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• 2018

의료수준의 향상과 더불어 환자들의 첨단의료장비에 대한 기대수준이 증가하고 있으며 특히 자기공명영상(Magnetic Resonance Image : MRI)은 현재 모든 임상 분야에서 가장 핵심적인 영상진단 도구로서 사용되고 있다. 그러나 검사 중에 발생하는 심각한 소음으로 많은 환자가 심리적인 불안을 경험한다고 한다. 이에 본 연구에서는 자기공명영상검사실의 기존 헤드셋 흡음재에서 차음재를 추가한 헤드셋의 소음저감평가와 차음재별 영상 아티팩트(artifact) 유무를 알아보고자 하였다. 3D 프린팅한 헤드셋 내부에 흡음재(스펀지)와 차음재(아크릴판, 구리판, 3D copper plate)를 교차 배열하여 MRI 검사소음을 녹음하여 스피커로 같은 dB 값의 소음을 발생시키며 3D 프린팅 된 두부모형의 내부에 소음측정기로 dB 값을 측정하여 정량분석을 하며 자체 제작한 헤드셋을 물팬텀에 밀착시킨 후 MRI영상 아티팩트 유무를 검사한다. 드셋의 정량평가를 한 결과, 헤드셋 평균 dB 값은 81.8 dB로 나타났으며, 차음재를 추가한 헤드셋에서 가장 방음효과가 뛰어난 재료조합(구리, 아크릴판, 스펀지, 스펀지) 헤드셋의 평균 dB 값은 70.4 dB 값이 측정되었지만 MRI 시뮬레이션 결과 구리가 반자성체이기 때문에 아티팩트가 나타나 배제하였고 두 번째로 방음효과가 뛰어난 (스펀지, 아크릴판, e-copper plate, 스펀지) 헤드셋의 평균 dB 값은 70.6 dB 값이 측정되었고 MRI 시뮬레이션 결과 인공물 나타나지 않았다. 구리분말이 약 40%가 포함된 e-copper PLA로 출력한 재료를 동일하게 시뮬레이션을 한 결과 인공물 나타나지 않았으므로 3D 프린팅 재료의 사용이 적합하였고 구리보다 경제성이 우수하며 가공이 용이하므로 적합한 재료로 선정하였다. MRI관련 연구에 있어 3D 프린팅을 이용한 상호발전이 매우 기대된다.

• 한국토양비료학회지
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• 제45권4호
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• pp.628-634
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• 2012

Release of veterinary antibiotics (VSs) to agricultural environment through application of animal manure and/or animal manure-based composts to soils is of concern. The current study was conducted to examine decline of VAs during composting the chicken manure. For this, antibiotics free chicken manure (20 kg) and sawdust (10 kg) were added to the bench-scale composting apparatus and then the mixed material was spiked simultaneously with three VAs (chlortetracycline, CTC; sulfamethazine, SMZ; tylosin, TYL) at two different levels (10 and $20mg\;kg^{-1}$). Then the decline of VAs was determined using Charm II system during 53 composting period. For comparison, composting only chicken manure was included at VAs concentration of $10mg\;kg^{-1}$. During composting, the concentration of all three different VAs declined below the prospective guideline values ($0.8mg\;kg^{-1}$ for CTC, $0.2mg\;kg^{-1}$ for SMZ, and $1.0mg\;kg^{-1}$ for TYL) except CTC at $20mg\;kg^{-1}$ spiking when the chicken manure was composted together with sawdust. Interestingly, CTC at $10mg\;kg^{-1}$ spiking appeared to be declined under the guideline value without sawdust while SMZ was resistant to be declined without sawdust. Unlike CTC and SMZ, TYL showed immediate decline right after spiking TYL to composting materials regardless the spiking concentration and existence of sawdust. Appropriate composting procedure of chicken manure was able to decline the residual VAs in the manure below the prospective guideline value and the importance of organic substances on this decline was perceived.

• 한국자기학회지
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• 제19권6호
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• pp.209-215
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• 2009

M-type 바륨 페라이트(BaFe12O19)분말을 공침법을 이용하여 합성하였다. 출발물질의 조성은 $Fe^{3+}:\;Ba^{2+}$ 몰 비를 8로 고정하고 $Fe^{3+}$와 $Ba^{2+}$의 상대적인 양을 조절하였다. 열처리 방법과 pH의 차이에 의한 자기적 성질과 결정구조, 입자형상의 변화를 XRD(XRay Diffractometer), FESEM(Field Emission Scanning Electron Microscope), VSM(Vibrating Sample Magnetometer)을 이용하여 조사하였다. pH가 8이고 $Fe^{3+}:\;Ba^{2+}$의 비가 12 : 1.5 일 때 가장 큰 보자력 값을 얻었다. pH가 8일 때는 $Fe^{3+}$와 $Ba^{2+}$의 상대적인 양과 열처리 조건에 따라 보자력과 포화 자화 값의 변화가 크게 나타났다. 이것은 바륨 페라이트로 전이가 안 된 $\alpha$-$Fe_2O_3$ 상 때문이다. pH가 10일 때는 열처리 조건과 $Fe^{3+}$와 $Ba^{2+}$의 양과 상관없이 단일 상 M-type 바륨 페라이트를 얻을 수 있었으며 우수한 자화 값과 보자력을 나타내는 분말을 얻을 수 있었다. $Fe^{3+}$와 $Ba^{2+}$의 비가 13.6 : 1.7일 때 가장 큰 자화 값(55.7 emu/g)을 얻을 수 있었으며, 산소분위기에서 열처리 후 노냉한 분말이 높은 보자력과 자화 값을 나타내었다. FESEM으로 관찰된 입자의 크기는 50~200 nm이었다.

• 한방안이비인후피부과학회지
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• 제16권3호
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• pp.200-209
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• 2003

Objectives : The aim of this study was to investigate the relationship between atopic dermatitis and the Sasang constitution. Methods : I examined 64 patients with moderate to severe atopic dermatitis for a long time who visited Department of Dermatology in Kangnam Korean Hospital, Kyunghee University and classified them into 4 types according to Sasang constitution under consulting a Sasang specialist. 1. The Sasang specialist classified the patients using the Questionnaire for the Sasang Constitution Classification Ⅱ(QSCCⅡ), body components examination, facial morphology measurement and Meridian function examination. 2. I analyzed the distribution of sex and age, first onset age, history period, digestion condition, existences of past history and family history, basal material volume, immunoglobulin E and eosinophil. Results and Conclusions : 1. As the distribution of sex and age, 28 patients(pts) were male and 36 pts were female. 20's female group was the most common. 2. As the distribution of Sasang constitution types, Soeumin were 28(43.7$\%$) pts, Taeumin were 24(37.5$\%$) pts, Soyangin were 11(17.2$\%$) pts, and Taeyangin was 1(1.6$\%$) pI. 3. As the mean age at first visit, Soeumin's was 20yrs, Taeumin's and Soyangin's were 27yrs, and Taeyangin's was 15yrs. 4. As the mean onset age, Soeumin's was 7yrs the lowest, Taeumin's was 15.7yrs, Soyangin's was 10.54yrs and Taeyangin's was 15yrs. 5. As the history period. Soeumin's was 13.8yrs. Taeumin's was 11.8yrs. Soyangin's was 16.5yrs. Tae yangin's was 13yrs. 6. As the existence of past history of atopic diseases, Soeumin were 12(43$\%$) pts, Taeumin were 7(29$\%$) pts and Soyangin were 5(45$\%$) pts. 7. As immunoglobulin E, 21(75$\%$) pts of Soeumin were normal, 7(25$\%$) pts were abnormal.. 22(92$\%$) pts of Taeumin were normal, 2(8$\%$) pts were abnormal. 8(73$\%$) pts of Soyangin were normal, 3(27$\%$) pts were abnormal. As the defecation condition, 19(68$\%$) pts of Soeumin were normal, 9(32$\%$) pts were abnormal. 14(58$\%$) pts of Taeumin were normal, 10(42$\%$) pts were abnormal, 8(73$\%$) pts of Soyangin were normal, 3(27$\%$) pts were abnormal. 8. The mean value of immunoglobulin E of Soeumin was 1236, Taeeumin was 442, Soyangin was 2010, the mean value of eosinophil of Soeumin was 3.5, Taeeumin was 2.47, Soyangin was 4.28.

• 한국재료학회지
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• 제22권11호
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• pp.591-597
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• 2012

For heat exchanger applications, 2-ply clad materials were fabricated by rolling of aluminum (Al) and mild steel sheets. Effects of annealing temperature on interface properties, especially on inter-layer formation and softening of strain hardened mild-steel, for Al/mild steel clad materials, were investigated. To obtain optimum annealing conditions for the Al/mild steel clad materials, annealing temperature was varied from room temperature to $600^{\circ}C$. At the annealing temperature about $450^{\circ}C$, an inter-layer was formed in an island-shape at the interface of the Al/mild steel clad materials; this island expanded along the interface at higher temperature. By analyzing the X-ray diffraction (XRD) peaks and the energy dispersive X-ray spectroscopy (EDX) results, it was determined that the exact chemical stoichiometry for the inter-layer was that of $Fe_2Al_5$. In some samples, an X-layer was formed between the Al and the inter-layer of $Fe_2Al_5$ at high annealing temperature of around $550^{\circ}C$. The existence of an X-layer enhanced the growth of the inter-layer, which resulted in the delamination of the Al/mild-steel clad materials. Hardness tests were also performed to examine the influence of the annealing temperature on the cold deformability, which is a very important property for the deep drawing process of clad materials. The hardness value of mild steel gradually decreased with increasing annealing temperature. Especially, the value of hardness sharply decreased in the temperature range between $525^{\circ}C$ and $550^{\circ}C$. From these results, we can conclude that the optimum annealing temperature is around $550^{\circ}C$ under condition of there being no X-layer creation.

• 한국자기학회지
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• 제8권2호
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• pp.67-73
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• 1998

perovskite Gd1-xSrxFeO3-y(x=0.0, 0.5) 시료의 결정학적 및 자기적 성질을 X-ray 회절과 Mossbauer 분광법 및 VSM를 이용하여 연구하였다. 결정 구조는 모두 orthorhormcis 구조를 가지며 Gd0.5Sr0.5FeO3-y의 격자상수는 a0=5.53$\AA$, bo=5.608$\AA$, C0=7.724$\AA$이었다. Gd1-xSrxFeO3-y(x=0.0, 0.05,)의 Mossbauer 실험을 4.2K부터 690K 온도 영역에서 수행하였고 Neel 온도는 GdFeO3 는 690K로 Gd0.5Sr0.5FeO3-y는 515K로 결정 하였다. GdFeO3 시료의 이온 상태는 Fe3+임을 알 수 있었고 Brillouin 함수값S=5/2를 만족하며 팔면체 자리를 나타내고 있다. Mossbauer spectrum과 Mohrdua 분석에 의해 Gd0.5Sr0.5FeO3-y 시료는 Fe3+와 Fe4+이온이 공존하여 존재합을 알았다.

• 콘크리트학회논문집
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• 제14권3호
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• pp.357-364
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• 2002

CLWL-DCB 시험편에 대한 변위제어 파괴실험으로 381mm의 균열성장에 대한 저항곡선이 유도되었다. 변형률 게이지를 사용하여 측정된 평균 균열성장속도는 0.70 mm/sec와 55mm/sec이었다. 초기균열에서 측정된 회전각도는 0.70 mm/sec와 55mm/sec의 균열속도에 대해 각각 최소한 171mm와 93mm의 균열성장 이전에 특이성이 존재하는 것을 보여주었다. 저항곡선의 최대 기울기는 0.70mm/sec 균열속도에 대해 25.4mm와 88.9mm 그리고 55mm/sec 균열속도에 대해 50.8 mm와 127mm의 균열성장길이 사이에서 발생되며, 미소균열 국부화에 의한 것으로 판단된다. 빠른 균열속도에서 미소균열성장 구역은 보다 길게 형성되며, 미소균열의 국부화 동안에도 큰 균열성장을 보였다. 0.70mm/sec 균열속도의 파괴저항은 152.4mm의 균열성장 이후에 평균 파괴에너지율의 약 70%인 143N/m의 비교적 일정한 값을 유지하였다. 55mm/sec 균열속도는 254mm 균열성장에서 최대 파괴저항 245N/m까지 증가한 후 파괴저항의 감소되어 불안정 균열성장이 발생될 수 있음을 보여준다. 55mm/sec 균열속도의 저항곡선은 TPB 실험과 유사하여, 시험편의 크기가 작거나 균열의 속도가 빠른 경우에 취성거동을 할 수 있는 것을 보여준다.

• 대한치과보철학회지
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• 제43권2호
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• pp.248-257
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• 2005

Statement of problem. Cortical bone plays an important role in the primary implant stability, which is essential to immediate/early loading. However, immediate load-bearing capacity and primary implant stability according to the change of the cortical bone thickness have not been reported. Purpose. The objectives of this study were (1) to measure the immediate load-bearing capacity of implant and primary implant stability according to the change of cortical bone thickness, and (2) to evaluate the correlation between them. Material and methods.48, screw-shaped implants (3.75 mm$\times$7 mm) were placed into bovine rib bone blocks with different upper cortical bone thickness (0-2.5 mm) and resonance frequency (RF) values were measured subsequently. After fastening of healing abutment. implants were subjected to a compressive load until tolerated micromotion threshold known for the osseointegration and load values at threshold were recorded. Thereafter, RF measurement after loading, CT taking and image analysis were performed serially to evaluate the cortical bone quality and quantity. Immediate load-bearing capacity and RF values were analyzed statistically with ANOVA and post-hoc method at 95% confidence level (P<0.05). Regression analysis and correlation test were also performed. Results. Existence and increase of cortical bone thickness increased the immediate load-bearing capacity and RF value (P<0.05) With the result of regression analysis, all parameter's of cortical bone thickness to immediate load-bearing capacity and resonance frequency showed significant positive values (P<0.0001). A significant high correlation was observed between the cortical bone thickness and immediate load-beating capacity (r=0.706, P<0.0001), between the cortical bone thickness and resonance frequency (r=0.753, P<0.0001) and between the immediate load-bearing capacity and resonance frequency (r=0.755, P<0.0001). Conclusion. In summary, cortical bone thickness change affected the immediate load-baring capacity and the RF value. Although RF analysis (RFA) is based on the measurement of implant/bone interfacial stiffness, when the implant is inserted stably, RFA is also considered to reflect implant/bone interfacial strength of immediately after placement from high correlation with the immediate load-baring capacity. RFA and measuring the cortical bone thickness with X-ray before and during surgery could be an effective diagnosis tool for the success of immediate loading of implant.

• 대한치과보철학회지
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• 제41권2호
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• pp.223-231
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• 2003

Statement of problem : Little is known about the effect of a counter-torque device and the internal hexagon of abutment on the tightening torque transmitted to the implant. Purpose : The purpose of this study was to examine the effect of a counter-torque device and the internal hexagon of abutment on the tightening torque transmitted to the implant. Material and Methods : In this study, three types of abutment were used, (1) two-piece conical abutment with hexagon, (2) two-piece conical abutment without hexagon, and (3) one-piece conical abutment without hexagon. The experimental groups were divided into five groups according to the type of abutment and the usage of a counter-torque device. Group I : two-piece conical abutment with internal hexagon was tightened without the use of a counter-torque device. Group II : two-piece conical abutment without internal hexagon was tightened without the use of a counter-torque device. Group III : one-piece conical abutment without internal hexagon was tightened without the use of a counter-torque device. Group IV : two-piece conical abutment with internal hexagon was tightened with the use of a counter-torque device Group V : two-piece conical abutment without internal hexagon was tightened with the use of a counter-torque device. Abutments were tightened 20Ncm torque with the use of manual torque wrench and then torque values were measured by torque-gauge. After the measurement of torque values, all groups were loosened with the use of manual torque wrench and then detorque values were measured by torque-gauge. Results : The results were as follows. 1. There were no differences in torque values among three types of abutment. 2. Regardless of the existence of the internal hexagon of abutment, a counter-torque device decreased the tightening torque transmitted to the implant about 92% 3. In group III showed the highest detorque value, however there were no differences among group I, II, IV and V. Conclusion : Within the limitations of this study, it was concluded that the internal hexagon of abutment has no effect on the tightening torque transmitted to the implant and the detorque value of abutment screw. The use of a counter-torque device is essential to prevent microfracture on the implant-bone interface but has no effect on preload.