• 대한수학회논문집
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• 제12권2호
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• pp.479-490
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• 1997

We consider long nonlinear waves in the two-layer flow of an inviscid and incompressible fluid bounded above by a free surface and below by a rigid boundary. The flow is forced by a bump on the bottom. The derivation of the forced KdV equation fails when the density ratio h and the depth ratio $\rho$ yields a condition $1 + h\rho = (2-h)((1-h)^2 + 4\rho h)^{1/2}$. To overcome this difficulty we derive a forced modified KdV equation by a refined asymptotic method. Numerical solutions are given and hydraulic fall solution of a two layer fluid is expressed analytically in the case that derivation of the forced KdV (FKdV) equation fails.

• 산업기술연구
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• 제29권B호
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• pp.107-113
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• 2009

For the environmental safety of the operating room and patient healthcare, the closed type rebreathing system is widely adopted. In order to reduce the anesthesia gas during surgery, the mixing ratio of anesthesia gas with breathing air should be precisely controlled. Generally, the breathing air passes through the vaporizer to mix the anesthesia gas, but there is a difficulty in controlling the mixing ratio precisely. In this paper, the stand-alone style vaporizer is designed and the operating characteristics are investigated. The vaporizer measures the temperature and pressure in the vaporizing chamber and chamber temperature is precisely controlled by proportional controlled heater. Exact quantity of anesthesia media is feeded by PID controlled peristaltic pump and vaporized gas is mixed with breathing air flow by PWM controlled solenoid valve. The experimental result shows that the vaporizer has an excellent command following performances that it can be applied to the low flow anesthesia system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1777-1782
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• 2003

This paper presents the design, fabrication, and testing of the capillary-induced pressure drop valve, thermocapillary pumping of liquid droplet in hydrophilic channels and the splitting of droplet. The capillaryinduced pressure drop is derived with thermodynamic approach considering three-dimensional meniscus shape which is essential for calculating pressure drop in the diverging shape channel when the aspect ratio is close to one. The micro channel is fabricated via MEMS processes, which consists of the liquid stop valve to retard the liquid droplet, thermocapillary pumping region and the bifurcation region. Also the micro heaters are fabricated to drive the droplet by thermocapillary. The theoretical approaches agree well with the experimental data. The functionality of capillary valve is confirmed to be valid when the aspect ratio is smaller than one. To overcome the difficulty in splitting of the droplet due to the pressure drop in the general Y-shape channel, the protrusion shape is employed for easy splitting in the bifurcation channel.

• 한국전산유체공학회지
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• 제2권1호
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• pp.129-137
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• 1997

We consider long nonlinear waves in the two-layer flow of an inviscid and incompressible fluid bounded above by a free surface and below by a rigid boundary. The flow is forced by a bump on the bottom. The derivation of the forced KdV equation fails when the density ratio h and the depth ratio ρ yields a condition 1＋hρ=(2-h)((1-h)²＋4ρh)/sup 1/2/. To overcome this difficulty we derive a forced modified KdV equation by a refined asymptotic method. Numerical solutions are given and hydraulic fall solution of a two layer fluid is expressed analytically in the case that derivation of the forced KdV(FKdV) equaition fails.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.20-33
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• 2015

Spectrum sensing is a key component of cognitive radio. The prediction of the primary user status in a low signal-to-noise ratio is an important factor in spectrum sensing. However, because of noise uncertainty, secondary users have difficulty distinguishing between the primary signal and an unauthorized signal when an unauthorized user exists in a cognitive radio network. To resolve the sensitivity to the noise uncertainty problem, we propose an entropy-based spectrum sensing scheme to detect the primary signal accurately in the presence of an unauthorized signal. The proposed spectrum sensing uses the conditional entropy between the primary signal and the unauthorized signal. The ability to detect the primary signal is thus robust against noise uncertainty, which leads to superior sensing performance in a low signal-to-noise ratio. Simulation results show that the proposed spectrum sensing scheme outperforms the conventional entropy-based spectrum sensing schemes in terms of the primary user detection probability.

• ETRI Journal
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• 제46권1호
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• pp.106-117
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• 2024

Large language models (LLMs) have revolutionized various applications in natural language processing and exhibited proficiency in generating programming code. We propose a framework for evaluating the code generation ability of LLMs and introduce a new metric, pass-ratio@n, which captures the granularity of accuracy according to the pass rate of test cases. The framework is intended to be fully automatic to handle the repetitive work involved in generating prompts, conducting inferences, and executing the generated codes. A preliminary evaluation focusing on the prompt detail, problem publication date, and difficulty level demonstrates the successful integration of our framework with the LeetCode coding platform and highlights the applicability of the pass-ratio@n metric.

• 정보처리학회논문지D
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• 제9D권1호
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• pp.75-80
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• 2002

Putnam은 소프트웨어 프로젝트에 참여하는 인력이 Rayleigh 분포를 따르는 SLIM 모델을 제시하였다. 이 모델에서 인력분포를 얻기 위해서는 총 개발노력과 개발 난이도를 추정해야 한다. 프로젝트 개발에 참여할 것인지 여부를 결정하기 위해서는 소프트웨어 생명주기의 초기단계에서 이 모수들을 보다 적확히 추정하는 것이 필요하다. Putnam은 시스템 속성들 중 강한 상관관계가 있는 변량을 제거하고 나머지 변량들만으로 총 개발노력과 개발 난이도를 추정하였다. 그러나 통계적 방법에 따라 변량들이 다르게 선택되며 모델의 성능에 차이가 발생한다. 본 논문은 Putnam 방법 대신 주성분분석을 이용하여 최적의 시스템 속성을 선택하였다. 모델의 성능분석 결과 주성분분석 방법이 Putnam의 방법보다 9.85% 성능향상을 보였다. 또한, 제안된 모델은 단순하고 쉽게 구현할 수 있다.

• 과학교육연구지
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• 제36권2호
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• pp.293-302
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• 2012

이 연구는 중학교 1학년 과학과 총괄 지필평가 출제경향을 조사하기 지필평가 문항의 행동영역, 내용영역, 문항유형, 난이도에 대하여 조사 분석하였다. 10개의 중학교의 1차와 2차 지필평가 문항의 총 645개를 연구대상으로 하여 분석하였다. 연구결과는 다음과 같다. 첫째, 지필평가 문항의 행동영역은 '지식, 이해' 수준으로 편중되어 있으며, 적용, 분석, 종합, 평가 영역의 문항은 거의 출제가 되고 있지 않았다. 둘째, 내용영역은 기존의 연구의 결과에 비해 과학적 탐구과정의 출제 빈도수가 많아졌지만, 여전히 과학지식을 묻는 문항이 과학적 탐구과정의 문항과 비교하여 두 배 이상의 비율로 출제되고 있음을 알 수 있었다. 셋째, 문항유형은 선다형 문항 중심으로 출제 되고 있는 것으로 조사되었다. 넷째, 정답률을 기준으로 문항의 난이도를 분석한 결과, 전체적인 빈도수에서 '상'에 해당하는 문항의 비율은 교사가 목표로 하는 난이도 비율보다 낮았으며, '중'의 비율은 교사가 생각하는 난이도 비율보다 높은 것으로 조사되었다. 과학학습에 대한 다양한 영역의 총체적인 평가를 위해서는 교사의 평가 및 문항 개발의 전문성 신장에 대한 노력이 이루어져야 할 것이다.

• 대한간호학회지
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• 제46권3호
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• pp.400-408
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• 2016

Purpose: This study was done to identify frequency, intensity of urinary dysfunction and daily life distress in women after a radical hysterectomy for cervical cancer. Methods: One hundred and fifty seven women who had undergone a radical hysterectomy and one hundred and sixty five women as healthy controls completed questionnaires on intensity of urinary dysfunction and daily life distress caused by urinary dysfunction. Results: Women with cervical cancer showed higher frequency of urinary dysfunction than healthy controls. Major urinary dysfunction for women with cervical cancer in order of frequency were night-time incontinence (odds ratio=10.39, p<.001), difficulty in starting urination, weak urine stream and sense of incomplete emptying of bladder. The highest score on intensity was difficulty in starting urination, followed by urgency, weak urine stream, daytime frequency and sense of incomplete emptying. Night-time incontinence was the urinary symptom causing the most daily life distress for cervical cancer women followed by difficulty in starting urination, urgency, sense of incomplete emptying, and night-time frequency. Conclusion: Results suggest that nurses should address the potential postoperative urinary complications and develop long term interventions to decrease urinary dysfunction and daily life distress for women who have had a radical hysterectomy for cervical cancer.

• 음성과학
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• 제11권2호
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• pp.105-117
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• 2004

Recently, many scholars have emphasized the importance of English listening ability for smoother communication. Most audio materials, however, were recorded in a quiet sound-proof booth. Therefore, students who have spent so much time listening to the ideal audio materials are expected to have difficulty communicating with native speakers in the real life. In this study, we examined how well thirty three Korean university students and five native speakers will repeat the recorded English sentences under noise and speed conditions. The subjects' production was scored by listening to each recorded sentence and counting the number of words correctly produced and determined the percent ratios of correctly produced words to the total words in each sentence. Results showed that the student group correctly repeated around 65% of all the words in each sentence while the native speakers demonstrated almost perfect match. It seemed that the students had difficulty perceiving and repeating function words in various conditions. Also, high-proficiency student group outperformed the low-proficiency student group particularly in their repetition of function words. In addition, the student subjects' accuracy of repetition remarkably dropped when the normal sentences were both sped up and mixed with noise. Finally, it was observed that the Korean students' percent correct ratio fell down as the stimulus sentence became longer.