• 지질공학
• /
• 제29권4호
• /
• pp.509-529
• /
• 2019

본 연구는 강변여과수 취수를 위한 충적우물에서의 필터재의 역할과 이중필터 취수정의 적용성 및 개선효과를 평가할 목적으로 수행하였다. 토층으로 이루어진 하천변의 자유면대수층에서 필터 조건을 달리 하여 실규모의 이중필터 취수정과 단일필터 취수정을 각각 설치하고 설치된 우물에서 대수성 시험을 실시하여 필터재 조건에 따른 수위강하특성, 투수특성, 적정 양수량 및 우물 효율을 평가하였다. 결과적으로, 이중필터층을 형성시켜 주는 것은 대수층과 필터층의 경계부에서 지하수 유동의 완충작용을 하여 유입되는 지하수의 급격한 속도변화를 최소화하는 효과를 나타내는 것으로 추정된다. 이는 난류 발생을 최대한 억제하여 보다 넓은 범위의 지하수를 효과적으로 취수정 내부로 유입시키는 역할을 하고 이로 인하여 취수량이 단일필터 취수정에 비해 높음에도 불구하고 주변 지하수위의 변화를 줄일 수 있는 것으로 보인다. 또한, 이중필터의 설치만으로도 기존 시스템(단일필터 취수정) 대비 투수성, 적정 양수량, 우물 효율이 개선됨을 시험을 통해 확인할 수 있었다. 본 연구의 결과는 앞서 수행한 다양한 연구와 종합하여 충적대수층에서의 이중필터 취수정 우물의 설계 및 시공에 대한 표준화된 기준을 마련하는데 활용할 계획이다. 또한, 강변여과수에 주로 적용되고 있는 단일 필터 취수정 및 방사상집수정과 대비하여 이중필터 취수정 적용 효과에 대한 객관적 입증 자료로의 활용이 기대된다.

• 가정과삶의질연구
• /
• 제35권1호
• /
• pp.1-16
• /
• 2017

Using data from the 2015 Korea Welfare Panel Study, we examined the predictors of psychological well-being (life satisfaction and depression) of single elderly people living alone across development stages (young-old, mid-old, and old-old) and suggested implications for elderly policy. For this purpose, we selected 1,364 elderly people who lived alone but preserved their family relationships, and were 65 years of age or older. Separate analyses were conducted for the three groups of single elderly people living alone. Overall, the psychological well-being of single elderly people living alone was higher than moderate level, and they were generally satisfied with their everyday lives and less depressed. However, there were group differences: the young-old group was more satisfied than the old-old group with in their everyday lives and less depressed than the mid-old and old-old groups. In the young-old group, life satisfaction was significantly associated with subjective health, non-physical conflict with family, disposal income, house ownership, dietary deficiency, cost of living, and public pension. In addition, depression was significantly associated with subjective health, non-physical conflict with family, dietary deficiency, and physical conflict with family. In the mid-old group, life satisfaction was significantly associated with subjective health, housing non-physical conflict with family, disposal income, and dietary deficiency. Depression was significantly associated with subjective health, housing deficiency. In the old-old group, life satisfaction was significantly associated with subjective health and non-physical conflict with family. Depression was significantly associated with subjective health. Therefore, 'health'and 'family'are important key concepts to consider when making elderly policy.

• 한국전기전자재료학회논문지
• /
• 제11권9호
• /
• pp.693-699
• /
• 1998

In this work $Cd_4GeS_6:Co^{2+}$(0.5mole%) single crystals were grown by the chemical transporting reactiov(CTR) method using high purity(6N) elements. The grown single crystals crystallized in a monoclinic structure(space group Cc). The direct optical energy gap of this single crystals was found to be 2.445eV at 300K and the temperature dependence of optical energy gap was fitted well to Varshni equation. But at temperatures lower than 70K an anomalous temperature dependence of the optical energy gap was obtained. This anomalous temperature dependence accored well with the anomalous temperature dependence of the unit cell volume. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gaps.

• 한국전기전자재료학회논문지
• /
• 제16권1호
• /
• pp.77-82
• /
• 2003

The ac loss is an important issue in the design of high-Tc superconducting power devices such as transformers and cables. In these devices many Bi-2223 tapes are closely stacked together and exposed to alternating magnetic fields that can have different orientations with respect to a tape. In such arrangement the magnetization loss is influenced by the screening current induced in adjacent tapes and thus different from that in a single tape. This stacking effect was experimentally investigated by measuring the magnetization loss in a stack, which consists of a number of tapes. First the magnetization loss in the single tape was measured in order to confirm the reliability of the loss data measured in the stack. The results for the single tape coincide well will the loss characteristics described in other previous works. For the stack In parallel and longitudinal magnetic fields the measured loss is Independent of both the number of tapes and stacking type. The longitudinal magnetization loss Is well explained rather by the slab model for decoupled filaments. For the tall stack in perpendicular field the measured loss at low fields is greatly decreased, compared to the loss of the single tape. However the loss at high fields is unaffected. These loss behaviors in the tall stack are well described by the slab model for full coupling.

• 대한소아치과학회지
• /
• 제51권2호
• /
• pp.176-184
• /
• 2024

This study aimed to compare color matching between single-shade composite resin-restored teeth with various pulp capping materials and the dentin surrounding the restoration through instrumental analysis and visual evaluation of the color difference. Fifty maxillary right central incisor acrylic resin teeth were prepared with standardized Class III cavities on the proximal surfaces. These teeth were divided into five groups: restored with single-shade composite resin only; Ultra-Blend^TM plus followed by single-shade composite resin; TheraCal PT^TM followed by single-shade composite resin; Endocem^® MTA premixed followed by single-shade composite resin; and Well-root PT^TM followed by single-shade composite resin. The color difference (ΔE_ab^*) between the restored area and the center of the resin teeth was measured using a spectrophotometer. No significant color difference was observed in groups restored with only single-shade composite resin, Ultra-Blend^TM plus, and TheraCal PT^TM. The visual evaluation revealed that Ultra-Blend^TM plus exhibited the best color matching score, whereas the Endocem^® MTA premixed and Well-root PT^TM groups showed significantly lower color matching scores than the single-shade composite resin-only group. When opting for single-shade composite resin usage for anterior tooth restorations with the aim of reducing chair time, pulp capping materials Ultra-Blend^TM plus and TheraCal PT^TM provide esthetically pleasing results.

• Tuberculosis and Respiratory Diseases
• /
• 제87권2호
• /
• pp.194-199
• /
• 2024

Background: In recent years, medical thoracoscopy has been well established to play an important role in undiagnosed pleural effusion; however, this procedure is underutilized due to limited availability of the instruments it requires. This study analysed the outcome of single port rigid thoracoscopy in patients with undiagnosed pleural effusions. Methods: This study retrospectively analysed the outcomes of all patients with undiagnosed pleural effusion presenting to our centre between 2016 to 2020 who underwent single port rigid medical thoracoscopy as a diagnostic procedure. Results: In total, 92 patients underwent single port rigid medical thoracoscopy. The most common presenting symptom was shortness of breath. A majority of the patients had lymphocytic exudative pleural effusion. The average biopsy sample size was 18 mm, and no major complication was reported in any of the patients. Conclusion: Single port rigid thoracoscopy is a safe and well-tolerated procedure that yields a biopsy of a larger size with high diagnostic yield. Moreover, the low cost of the instruments required by this procedure makes it particularly suited for use in developing countries.

• 한국통신학회논문지
• /
• 제19권3호
• /
• pp.591-596
• /
• 1994

Gain-guided 구조를 갖는 단일양자우물 laser diode에서, stripe 폭에 따른 threshold의 변화를 복소수영역 유효굴적률방법을 이용하여 분석하였다. 분석결과 stripe 폭이 좁은 영역에서는, 측방향광집속률을 나타내기위하여 세롭게 도입된 변수 가 수직방향광집속률 가 감소함에따라 급격하게 감소하는 경향을 알아내었다. 따라서 일반적으로 매우작은 수직방향광집속률을 갖는 단일양자우물 laser diode에서는, stripe 폭의 크기에 따라서는 광집속률이 측방향은 물론 수직방향으로도 매우 나빠지게 됨으로 이득포와현상을 더욱 심하게시키게되며 경우에 따라서는 문턱전류가 비정상적으로 증가하는 현상으로 이어지게된다. 이와같은 문턱치의 stripe 폭에 대한 약간의 비정상적인 의존성을 이해하는 것은 양자우물 laser diode의 구조최적화에 있어서 매우 중요한 일이라고 판단된다.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2005년도 제16회 정기총회 및 동계학술발표회
• /
• pp.12-13
• /
• 2005

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 F
• /
• pp.1931-1933
• /
• 1998

In this paper, single-phase PWM AC to AC converter that operates with unit power factor and sinusoidal input line currents is presented. The output voltage of this converter is able to be obtain step up voltage as well as step down voltage. because the converter applies to operating method of buck-boost converter. The control of this converter is performed with PI control method. By using this control method low lipples in the output current and the voltage as well as fast dynamic response are achieved.

• 동력기계공학회지
• /
• 제3권4호
• /
• pp.69-78
• /
• 1999

In the single-input and single-output system, the parameter of plant is scalar polynomial, but in the multiple input and multiple output, it accompanies, being matrix polynomial, the consideration of observable controlability index or problems non-commutation in matrix polynomial as well as degree, and it is more complex to deal with. Therefore, it is thought that a full research on the single-input and single-output system is not sufficient. This paper proposes that problems of minimum variance self-tuning regulator by using numerical calculation example of multivariable system and pole assignment self-tuning regulator.