• 대한기계학회논문집A
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• 제27권1호
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• pp.8-17
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• 2003

Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear Power Plant. In Pipes of energy Plants, sometimes, the local wall thinning may result from severe erosion-corrosion (E/C) damage. However, the effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. From the tests, fracture behaviors and fracture strength of locally thinned pipe were manifested systematically. The observed failure modes were divided into four types; ovalization. crack initiation/growth after ovalization, local buckling and crack initiation/growth after local buckling. Also, the strength and the allowable limit of piping system with local wall thinning were evaluated.

• Journal of Dental Anesthesia and Pain Medicine
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• 제20권4호
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• pp.187-194
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• 2020

Background: The aim of the present systematic review was to evaluate and compare the efficacy of warmed and unwarmed local anesthesia solutions in reduction of pain during intraoral injection administration. Methods: PubMed, Ovid SP, and Cochrane Central Register of Controlled Trials were searched from publication years 1990 to 2020 with relevant MeSH terms. Studies were screened by titles and abstracts, followed by full-texts evaluation of the included studies. Results: A total of four studies were included in the systematic review. Outcomes evaluated were subjective and objective pain during administration of the warmed local anesthesia solution in comparison with the unwarmed local anesthesia solution. Among the four studies that evaluated the self-reported pain score, three studies showed significantly lower pain scores associated with warmed local anesthesia. Only two studies evaluated the observed pain score, and both of them reported a significantly lower pain reaction with the warmed local anesthesia solution. Conclusion: Within the limits of this systematic review, warming the local anesthesia solution to body temperature (37℃) before administration seemed to reduce the discomfort during intraoral local anaesthesia administration, and more high-quality studies should be carried out to validate the same.

• 한국토양비료학회지
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• 제6권4호
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• pp.231-237
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• 1973

Phytotron을 사용(使用) 열대형질(熱帶形質)인 IR667 계통(系統)(수원 213 및214)과 기존장려품종(진흥(振興) 및 팔달(八達))의 생육(生育) 시기별(時期別)(묘대말기(苗代末期), 최분기(最分期), 출수기(出穗期))로 저온처리(低溫處理)($15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$, 3일(日) 및 7일간(日間))를 하여 엽록소(葉綠素), 질소(窒素) 및 가리(加里) 함량(含量)의 변화(變化)를 상부제(上部第) 2엽신(葉身)에서 조사(調査)하였다. 1. chl. 함량이 $25^{\circ}C$ 에서는 IR667계통(系統)이 장여품종(奬勵品種)보다 크나 $20^{\circ}C$이하(以下)에서는 그 반대(反對)였으며 chi. a/b 값은 장려품종(奬勵品種)이 언제나 큰 경향이다. 2. 엽록소함량(葉綠素含量)은 생육(生育)에 따라 감소(減少)하며 chl.a가 b 보다 저온(低溫)에 의(依)한 감소(減少)가 크고 묘대기(苗代期)가 저온(低溫)의 영향(影響)을 가장 심히 받았다. 3. chl. 함량(含量)이 증가(增加)할수록 chl. a/b 값도 증가(增加)하는데 장해(障害)를 받으면 chi.당(當) a/b. 비율(比率) 증가(增加)가 감소(減少)하며 저온(低溫)에 약(弱)한 IR667이 장려품종보다 더욱 감소(減少)한다. 4. Chl. 잔존율(殘存率)로 보아 IR667계통(系統)이 장려품종(奬勵品種)보다 저온장해(低溫障害)를 크게 받는다. 5. 전질소(全窒素) 및 methanol 가용질소(可溶窒素)(S-N)는 저온(低溫)에 의(依)하여 감소(減少)하는 경향(傾向)이다. 6. chl. (a+b)/S-N 값은 생육(生育)에 따라 감소하며 온도(溫度)에 크게 영향(影響)받지 않으며 장려품종(奬勵品種)이 언제나 큰 경향(傾向)이다. 7. 저온(低溫)에 의하여 K함량(含量)은 감소(減少)하는 경향(傾向)이며 methanol 가용(可溶)K가 증가(增加)하면 chlorophyll 함량(含量)도 증가(增加)하는 경향(傾向)이다. 8. IR667이 고온(高溫)에서 생체당(生體當) chlorophyll 함량(含量)이 많은 것은 이의 다수성(多收性)의 한 원인(原因)이며 chl. /S-N가 적은것은 엽신(葉身)의 저온(低溫)이나 비절(肥切)에 의(依)한 적변(赤變)의 한 원인(原因)이 될 것으로 보였다.

• 한국전기전자재료학회논문지
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• 제22권8호
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• pp.632-636
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• 2009

The local oxidation using an atomic force microscopy (AFM) is useful for Si-based fabrication of nanoscale structures and devices. SiC is a wide band-gap material that has advantages such as high-power, high-temperature and high-frequency in applications, and among several SiC polytypes, 4H-SiC is the most attractive polytype due to the high electron mobility. However, the AFM local oxidation of 4H-SiC for fabrication is still difficult, mainly due to the physical hardness and chemical inactivity of SiC. In this paper, we investigated the local oxidation of 4H-SiC surface using an AFM. We fabricated oxide patterns using a contact mode AFM with a Pt/Ir-coated Si tip (N-type, 0.01-0.025 ${\Omega}cm$) at room temperature, and the relative humidity ranged from 40 to 50 %. The height of the fabricated oxide pattern (1-3 nm) on SiC is similar to that of typically obtained on Si ($10^{15}^{\sim}10^{17}$ $cm^{-3}$). We perform the 2-D simulation to further analyze the electric field between the tip and the surface. We demonstrated that a specific electric field (4 ${\times}$ $10^7\;V/m$) and a doping concentration ($^{\sim}10^{17}$ $cm^{-3}$) is sufficient to switch on/off the growth of the local oxide on SiC.

• 한국초전도ㆍ저온공학회논문지
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• 제16권4호
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• pp.21-25
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• 2014

In order to develop 2nd generation (2G) high-temperature superconducting (HTS) wires as commercial products, it is necessary to perform a high speed investigation of their superconducting performance. Room-temperature and non-contact optical scanning tools are necessary to verify the microstructure of the superconducting materials, the current flow below the critical temperature, and the critical current density. In this paper, we report our results of an inspection of the electrical transport properties of coated conductors. The samples that we used in our study were highly qualified rare-earth based coated conductors produced via co-evaporation, and $SmBa_2Cu_3O_{7-y}$ (SmBCO) was the superconducting materials used in our studies. A film grown on IBAD-MgO templates shows larger than 400 A/cm at 77 K and a self-field. The local transport properties of the films were investigated by room-temperature imaging by thermal heating. The room-temperature images show structural inhomogeneities on the surface of the films. Bolometric response imaging via low-temperature bolometric microscopy was used to construct the local current mapping at the surface. These results indicate that the non-uniform regions on the surface disturb the current flow, and laser scanning images at room-temperature and at a low-temperature suggest a correlation between the structural properties and transport properties. Thus this method can be effective to evaluate the quality of the coated conductors.

• Geomechanics and Engineering
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• 제32권2호
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• pp.137-144
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• 2023

The current article studied wave propagation in a nonlocal porous thermoelastic half-space with temperature-dependent properties. The problem is solved in the context of the Green-Lindsay theory (G-L) and the Lord- Shulman theory (L-S) based on thermoelasticity with memory-dependent derivatives. The governing equations of the porous thermoelastic solid are solved using normal mode analysis with an eigenvalue approach. In order to illustrate the analytical developments, the numerical solution is carried out, and the effect of local parameter and temperature-dependent properties on the physical fields are presented graphically.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.77-80
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• 2003

We design the local oscillator system of the 100 GHz band radio receiving system for a cosmic radio observation. We use the YIG oscillator with digital driver which is the main oscillator. This oscillator has a good frequency and phase stability at some temperature variation, and the easy computer aided control characteristics. This total system designed to two subsystem, first is the oscillator system include YIG oscillator, tripler, harmonic mixer and triplexer etc., second is the PLL system to supply the precise and stable local oscillator frequency to mixer. The proposed local oscillator system in this paper can be use a single or multi pixel receiver because this system can be lock the local oscillator frequency automatically using PC.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.655-663
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• 2024

In order to meet the technological demand for indoor heating systems that ensure winter thermal comfort during the transition from internal combustion engines to electrification, a localized proximity heating module using surface heating elements was developed. The operational performance of heating module was tested in the low temperature chamber. The experiment conditions were varied by changing the chamber temperature (-10, 0℃), the air flow rate (6.2, 6.0, 4.2m³/h), the heater power (100, 80, 60, 40W). Thermal comfort model was confirmed using the CBE Thermal Comfort Tool applying ASHRAE standard 55. Under -10℃ condition, thermal comfort was satisfied at 23.4, 23.2℃ at power of 100W and air flow rate 6.0, 4.6m³/h. Under 0℃ condition, at power of 80W, air flow rate 6.2, 6.0m³/h, and at power of 60W, air flow rate 4.6m³/h showed results of 25.7, 26.1, 23.0℃, respectively, satisfying thermal comfort. This study analyzed the operating performance of the local proximity heating module in the low temperature chamber and applied thermal comfort model to prove applicability of local proximity heating module using surface heating elements and how to utilize the thermal comfort model.

• 대한기계학회논문집A
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• 제33권12호
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• pp.1393-1400
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• 2009

The objective of this study is to validate local failure criteria, which were proposed based on the notched-bar specimen tests combining with finite element (FE) simulations, using the results of real-scale pipe failure tests. This study conducted burst test using wall-thinned pipe specimens, which were made of 4 inch Sch.80 ASTM A106 Gr.B carbon steel pipe, under simple internal pressure at ambient temperature and performed associated FE simulations. Failure pressures were estimated by applying the failure criteria to the results of FE simulations and were compared with experimental failure pressures. It showed that the local stress based criterion, given as true ultimate tensile stress of material, accurately estimated the failure pressure of wall-thinned pipe specimens. However, the local strain based criterion, which is fracture strain of material as a function of stress tri-axiality, could not predict the failure pressure. It was confirmed that the local stress based criterion is reliably applicable to estimation of failure pressure of local wall-thinned piping components.

• 대한토목학회논문집
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• 제29권2B호
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• pp.141-153
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• 2009

우리나라에서 발생하는 호우의 발생원인은 태풍과 집중호우로 구분할 수 있다. 태풍은 비정기적으로 우리나라에 영향을 끼치며 막대한 강우를 유발시키며, 집중호우는 전선형 호우와 같은 장마와 지형성 호우인 국지성 호우를 의미한다. 태풍과 집중호우는 매년 우리나라에 극한강우를 발생시킴으로써 침수 등의 재해를 유발시키고 있다. 따라서 본 연구에서는 호우의 원인을 태풍과 집중호우로 구분하여, 집중호우로 인한 강우자료를 이용하여 확률강우량을 산정하였다. 집중호우에 대한 평가는 돌발홍수와 같은 짧은 지속시간의 호우에 대한 분석에 활용할 수 있다. 확률강우량의 산정방법은 일반적인 매개변수적 지점빈도해석과 EST를 적용하였다. EST의 적용을 위하여 해수면온도 및 습윤지수와 같은 수문기상인자와 집중호우로 인한 연최대시간강수량과의 상관성 분석을 수행하였다. 상관성 분석 결과에서 우리나라의 집중호우로 인한 강우량은 해수면온도와 밀접한 관련이 있는 것으로 나타났다. 또한, EST에 의해 산정된 확률강우량은 빈도해석한 확률강우량에 비하여 경기도 등의 우리나라의 서중부 지역에서 보다 큰 결과를 나타내었다. 따라서 우리나라의 서중부 지역에서는 집중호우로 인한 극한강우 발생에 대비해야 할 필요성이 있다.