• 한국지반신소재학회논문집
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• 제16권4호
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• pp.57-66
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• 2017

준설 매립 부지의 최종 계획고를 얻기 위한 초기 준설 매립량과 매립두께를 결정하고 자중압밀에 소요되는 시간을 예측하기 위해 인천지역 항로 준설 시료에 대한 자중압밀시험과 공학적 특성을 분석하였다. 준설투기된 시료의 시간경과에 따른 함수비, 간극비 및 체적변화비에 관한 인자를 Yano의 경험식을 이용하여 평가하였다. 세립분 함유율이 낮은 경우 침강압밀계수의 변화폭이 작게 나타났으며, 세립분 함유율 50%에서 가장 크게 나타났다. 자중압밀에 따른 체적변화비를 이용하여 준설매립공사에 제시된 입도별 유보율의 포괄적인 측면을 보완할 수 있는 세립분 함유율에 따른 유보율을 산정하여 제시하였다.

• 분석과학
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• 제12권3호
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• pp.203-208
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• 1999

살리실산 및 그 유도체들의 이온쌍 고성능 액체크로마토그래피 용리거동을 이동상 중 이온쌍 시약(tetrabutylammonium chloride, TBACl)의 농도를 변화시키면서 용량인자, k'를 측정함으로서 고찰하였다. 이동상의 pH 및 TBACl의 농도가 증가함에 따라 시료들의 k'는 증가하였다. 살리실산 정량의 최적 이동상 조건은 pH 7.2에서 20 mM TBACl을 함유한 메탄올 용액($MeOH:H_2O$ 30:70), p-아미노살리실산(PAS)은 40 mM TBACl을 함유한 메탄올 용액($MeOH:H_2O$ 20:80) 이었다. 머무름 거동의 관찰로부터 발견한 최적 조건에서 몇 가지 유도체들을 분리하였으며 아울러 아스피린과 결핵 치료제 중 살리실산 유도체들의 함량을 조사하였다.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.1947-1953
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• 2022

As the plasma facing material in the nuclear fusion reactor, tungsten has to bear the irradiation impact of high energy particles. The surface quality of tungsten may affect its irradiation resistance, and even affect the service life of fusion reactor. In this paper, tungsten samples with different surface quality were polished by mechanical processing, subsequently conducted by D₂⁺ implantation and thermal desorption. D₂⁺ implantation was performed at room temperature (RT) with the irradiation dose of 1 × 10²¹ D₂⁺/m² by 5 keV D₂⁺ ions, and thermal desorption spectroscopy measurements were done from RT to 900 K. In addition, He irradiation was also performed by 50 eV He⁺ ions energy with the fluxes of 5.5 × 10²¹ m^-2s^-1 and 1.5 × 10²² m^-2s^-1, respectively. Results reveal that the hydrogen/helium irradiation behavior are both related to surface quality. Samples with high surface quality has superior D₂⁺ retention behavior with less D₂ retained after implantation. However, such samples are more likely to generate fuzzes on the surface after helium irradiation. Different morphologies (smooth, wavy, pyramids) after helium irradiation also demonstrates that the surface morphology is related to tungsten crystallographic orientation.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.306-311
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• 2002

This paper propose a personalized defection detection and prevention procedure based on the observation that potential defectors have tendency to take a couple of months or weeks. For this purpose, possible states of customer behavior are determined from past behavior data using SOM (Self-Organizing Map). For the evaluation of the proposed procedure, a case study has been conducted for a Korean online game site. The result demonstestes that the proposed procedure can assist defection prevention effectively and detect potential defectors without deterioration of prediction accuracy comparison to prediction by MLP. Our procedure can be applied to various service industries that can capture fluent customer behavior data such as telecommunications, internet access services, and content services, too.

• 한국토양환경학회지
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• 제2권1호
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• pp.21-34
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• 1997

고속도로변에 설치된 간이정화시설은 drainage system의 일부분으로 우기에 빗물의 양을 조절하고 고속도로 노면에서 운반되어 간이정화시설에 유입된 오염된 입자를 침전, 제거시키기 위해 설치되었다. 빗물에 입자상태로 이동된 납, 아연, 카드뮴를 제거하기 위해 설치된 간이정화시설의 효과를 평가하기 위해 수리지질학적 연구 및 부유퇴적물의 물리화학적 특성을 규명하기 위한 연구가 수행되었다. 부유퇴적물과 비교하기 위해 심하게 오염된 도로변토양과 오염되지 않은 background soil에 대해서도 연구가 수행되었다. 부유퇴적물의 중금속함량은 background Sologne soil에 비해 원소에 따라 2~8배 높게 나타났다. 그러나, 도로변토양의 중금속함량은 부유퇴적물에 비해 7~26배 높게 나타났다. Sequential extraction methods (Tessier et al., 1979)를 이용하여 분석한 결과 심하게 오염된 도로변토양에 존재하는 납, 아연, 카드뮴은 대부분 쉽게 용해될 수 있는 상태 (Fraction FII, FIII)로 존재하며 반면에 규산염광물과 수반되는 금속함량의 비율은 매우 낮았다. 부유퇴적물에서는 규산염광물과 수반되는 금속함량이 전체 금속함량의 113까지 크게 증가하였다. 납과 아연은 fraction FI에서 거의 용해되지 않았는 반면에 (전체 함량의 약 3%) 카드뮴은 가장 용해성이 높은 fraction FI("exchangeable" )에서 상당량이 용해되었으며 특히 도로변토양의 경우 전체 카드뮴 함량의 1/4을 차지하였다. 도로변토양과 부유퇴적물사이의 중금속함량 차이가 매우 큰 것은 중금속의 대부분이 간이정화시설에 이르기전에 고속도로변과 배수로 일부에 축적되어 모두 상실되었기 때문이다.

• 한국초전도ㆍ저온공학회논문지
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• 제9권2호
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• pp.11-14
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• 2007

The critical current, $I_c$, degradation behaviors with bending strain were investigated in a commercially available YBCO coated conductor tape. In particular, the strain reversibility of $I_c$ and the influence of repeated bending on $I_c$ have been studied. Also, repeated bending at 77 K was done in order to understand the Ie behavior under cyclic bending strains. A reversible behavior of $I_c$ has been found up to a high bending strain of 1.60% for the RABiTS/MOD processed CC sample with copper reinforcement. Under repeated bending, the Ie showed a 95% $I_c$ retention up to 100 cycles for bending strains of 1.0% or less. The n-value behavior showed a good agreement with the $I_c$ degradation behavior, representing that any cracking did not occur on the YBCO film resulting from the reinforcement provided by the copper stabilizers.

• Clinical and Experimental Pediatrics
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• 제48권4호
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• pp.355-362
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• 2005

Constipation is very common phenomenon during childhood that accounts approximately 3% of general pediatric outpatient visits and up to 25% of visit to the pediatric gastroenterologist. The diagnosis of functional constipation is based on the historical features and absence of physical abnormalities. Most infants and children with chronic constipation require no diagnostic tests. Constipation and subsequent fecal retention behavior often begins soon after experience of painful defecation. The effective management of childhood chronic constipation consist of education, prolonged support by physicians and parents, medications, and long term follow up.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.368.1-368.1
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• 2014

We proposed amorphous GeSe-based ReRAM device of metal-insulator-metal (M-I-M) structure. The operation characteristics of memory device occured unipolar switching characteristics. By introducing the concepts of valance-alternation-pairs (VAPs) and chalcogen vacancies, the unipolar resistive switching operation had been explained. In addition, the current transport behavior were analyzed with space charge effect of VAPs, Schottky emission in metal/GeSe interface and P-F emission by GeSe bulk trap in mind. The GeSe ReRAM device of M-I-M structure indicated the stable memory switching characteristics. Furthermore, excellent stability, endurance and retention characteristics were also verified.

• Computers and Concrete
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• 제4권3호
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• pp.187-206
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• 2007

A rational three-dimensional nonlinear finite element model is described and implemented for evaluating the behavior of high strength concrete slabs under transverse load. The concrete was idealized by using twenty-nodded isoparametric brick elements with embedded reinforcements. The concrete material modeling allows for normal (NSC) and high strength concrete (HSC), which was calibrated based on experimental data. The behavior of concrete in compression is simulated by an elastoplastic work-hardening model, and in tension a suitable post-cracking model based on tension stiffening and shear retention models are employed. The nonlinear equations have been solved using the incremental iterative technique based on the modified Newton-Raphson method. The FE formulation and material modeling is implemented into a finite element code in order to carry out the numerical study and to predict the behavior up to ultimate conditions of various slabs under transverse loads. The validity of the theoretical formulations and the program used was verified through comparison with available experimental data, and the agreement has proven to be very good. A parametric study has been also carried out to investigate the influence of different material and geometric properties on the behavior of HSC slabs. Influencing factors, such as concrete strength, steel ratio, aspect ratio, and support conditions on the load-deflection characteristics, concrete and steel stresses and strains were investigated.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1986년도 추계학술대회
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• pp.510.1-510
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• 1986

Many enzymes require the participation of readily dissociable coenzymes as NAD for thir catalytic activities. The continuous utilization of the enzymes requires the retention and regeneration of the coenzymes. For this purpose, several kinds of macromolecular NAD derivatives have been prepared by covalently attaching NAD to watersoluble polymers. We have prepared poly (ethylene glycol)-bound NAD (PEG-NAD) by coupling N$\^$6/-(2-carboxyethyl)-NAD to one terminal of ${\gamma}$ $\omega$-diaminoly (ethylene glycol) (Mr 3000) with water-soluble carbodiimide. PED-NAD thus obtained has one NAD moiety located at a terminal of the linear, flexible and hydrophilic chain of poly (ethylene glycol). PED-NAD has good coenzyme activity for various dehydrogenases and is applicable in a continuous enzyme reactor. To use these macromolecular NAD derivatives in an enzyme reactor, it si necessary to understand the behavior of the system in which the reactions of dehydrogenases are coupled by the recycling of the NAD derivative. We investigated the kinetic properties of a continuous enzyme reactor containing lactate dehydrogenase, alcohol dehydrogenase and PEG-NAD. The steady-state behavior of the enzyme reactor is explained by a simple kinetic model.