• Title/Summary/Keyword: cross sectional method

Search Result 1,324, Processing Time 0.025 seconds

Prediction of Curvature Effects on the Electromagnetic Flowmeter Characteristics with Numerical Simulation (Laminar flow) (곡관의 곡률에 따른 전자기유량계 설치효과의 수치모사에 의한 특성 예측(충류))

  • Lim, Ki Won;Choi, Sang Kyu;Chung, Myung Kyoon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.23 no.11
    • /
    • pp.1453-1463
    • /
    • 1999
  • An electromagnetic flowmeter, based on a magnetic induction principle; provides an obstructionless flowmeter that essentially averages the velocity distribution over the pipe cross-sectional area. To predict the installation effects, the flowmeter installed near $90^{\circ}$ elbow is simulated by using a commercial code FLUENT(ver. 4.48) for the laminar flow field and a code developed through this study for magnetic field. The installation effects of the flowmeter are estimated by varying a number of the dependent parameters such as the radius of the elbow(Rc=1D, 1.5D, 2D, 3D), the location, Reynolds number and the direction of electrodes plane(${\varphi}$). It was found that all these factors affect the performance of the electromagnetic flowmeter significantly. The longer installation distance from the elbow is not always optimal to minimize the error, and also there exists an optimal location to install the EMF for a minimum error. Especially the flow signal with the electrodes plane direction of ${\varphi}=45^{\circ}$ is shown to yield smallest measurement error regardless of the Reynolds number and the curvature of elbow.

Salt Preference and Sodium Intake among Pregnant Women (임부의 염분 기호도와 식이섭취, 소디움 섭취 실태)

  • Im, Mi Jeung;Cho, Dong Sook
    • Women's Health Nursing
    • /
    • v.22 no.4
    • /
    • pp.297-307
    • /
    • 2016
  • Purpose: This study was to estimate salt preference and sodium intake of pregnant women, and identify the relationship between salt preference and sodium intake. Methods: Research design was a cross sectional correlational survey with 197 pregnant women who visited outpatient clinics for antenatal care. The sodium intake levels were estimated by the amounts of sodium intake using the 24-hour recall method and sodium concentration in spot urine. The data were analyzed using descriptive statistics, t-test, ANOVA and Pearson's correlation. Results: Sodium intake using 24-hour recall method was $3,504{\pm}1,359mg$. Sodium intake levels had statistically significant differences depending on income. The average amount of sodium in spot urine was $2,882{\pm}878mg/day$. Sodium excretion levels had statistically significant differences depending on whether participants had preexisting hypertension in their family history and Body Mass Index (BMI) pre-conception. Salt preference was $62.61{\pm}20.96$ out of 180 points. Salt preference had significant differences depending on income, parity, gestational age, BMI pre-conception and showed negative correlation with sodium quantity in spot urine. Conclusion: Sodium intake in pregnant women recommended by World Health Organization recommended is 175%. Salt preference was not significantly different between sodium intake levels, however it was negatively correlated with sodium quantity in spot urine among pregnant women.

Iron Core Design of 3-Phase 40MVA HTS Power Transformer Considering Voltages per Turn

  • Lee, Chan-joo;Seok, Bok-yeol
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
    • /
    • v.4B no.2
    • /
    • pp.54-58
    • /
    • 2004
  • This paper presents the iron core design method of a high temperature superconducting (HTS) transformer considering voltages per turn (V/T). In this research, solenoid type HTS coils were selected for low voltage (LV) winding and double pancake coils for high voltage (HV) winding, just as in conventional large power transformers. V/T is one of the most fundamental elements used in designing transformers, as it decides the core cross sectional area and the number of primary and secondary winding turns. By controlling the V/T, the core dimension and core loss can be changed diversely. The leakage flux is another serious consideration in core design. The magnetic field perpendicular to the HTS wire causes its critical current to fall rapidly as the magnitude of the field increases slowly. Therefore in the design of iron core as well as superconducting windings, contemplation of leakage flux should be preceded. In this paper, the relationship between the V/T and core loss was observed and also, through computational calculations, the leakage magnetic fields perpendicular to the windings were found and their critical current decrement effects were considered in relation to the core design. The % impedance was calculated by way of the numerical method. Finally, various models were suggested.

Effect of Tunnel Entrance Hood on Entry Compression Wave (입구후드가 고속철도 터널입구의 압축파에 미치는 영향)

  • Kim, Heuy-Dong;Kim, Tae-Ho;Kim, Dong-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.23 no.1
    • /
    • pp.58-68
    • /
    • 1999
  • The entry compression wave, which forms at the entrance of a high-speed railway tunnel, is closely related to the pressure transients in the train/tunnel systems as well as an impulsive noise appearing at the exit of the tunnel. In order to alleviate such undesirable phenomena, some control strategies have been applied to the compression wave propagating inside the tunnel. The objective of the current work is to investigate the effect of tunnel entrance hoods on the entry compression wave at the vicinity of the tunnel entrance. Three types of entrance hoods were tested by the numerical method using the characteristics of method for a wide range of train speeds. The results show that the maximum pressure gradient of compression wave can be considerably reduced by the tunnel entrance hood. Optimum hood shape necessary to reduce the pressure transients and impulsive noise was found to be of an abrupt type hood with its cross-sectional area 2.5 times the tunnel area. It is believed that the current results are highly useful in predicting the effects of entrance hoods and in choosing the shape of proper hood.

A Study on Evaluation of an RN-BSN Program in a Nursing School (일 대학의 RN-BSN 교육과정 평가)

  • Oh, Ka-Sil;Lee, Kyung-Ja;Kim, In-Sook;Kim, Hee-Soon;Oh, Eui-Geum;Lee, Ju Hee
    • The Journal of Korean Academic Society of Nursing Education
    • /
    • v.14 no.1
    • /
    • pp.38-45
    • /
    • 2008
  • Purpose: The purpose of this study was to evaluate the overall RN-BSN program, current curriculum, and student outcomes in one nursing college. Method: A cross- sectional survey was used for current students (n=152) and graduates (n=54). Three different instruments were used in this study; K-Regis University RN-BSN Program Evaluation Tool, Curriculum Evaluation Tool, and Outcome Evaluation Tool. Result: Results showed that overall the program was satisfying to current students and graduates. However, curriculum evaluation showed that clinical practicum and nursing skill courses were generally unsatisfying, indicating further changes in these areas. Graduates showed higher leadership and professionalism than current students in the outcome evaluation. Conclusion: The current study indicates a need for further studies such as review of the RN-BSN program philosophy and education method, or program evaluation by periods. Additionally, there is a need for a strategic plan to develop the RN-BSN program in the future.

Status and Perception of Nursing Handover among Korean Nurses in Intensive Care Units (중환자실에서 이루어지는 간호사 인수인계 실태 및 인수인계에 대한 평가)

  • Kim, Chun Mi;Kim, Eun Man;Ko, Ji Woon
    • Journal of Korean Critical Care Nursing
    • /
    • v.8 no.2
    • /
    • pp.13-22
    • /
    • 2015
  • Purpose: This study identified the current status and perception of intensive care unit nurses' handover. Methods: A cross sectional descriptive survey was employed. The population included nurse managers and staff nurses who worked in intensive care units in hospitals with more than 500 beds and excluded nursing homes, psychiatric hospitals, and military hospitals. Results: Of the nurses, 61.7% were satisfied with the current handover method, 68.36% had no handover-related guidelines, and 83.2% of them perceived that the handover was important for patients' safety. The most frequent cause for errors related to handover was that the "nursing workload is heavy." The nurses perceived that their handover was informative ($5.62{\pm}0.79$) and efficient ($5.04{\pm}0.98$). The variables associated with their perception of the handover were the level of satisfaction with the current handover method, existence of handover guidelines, and importance of handover for patient safety. Conclusion: The development of standardized handover guidelines, especially for intensive care units, is necessary to reduce handover time and errors and to improve handover quality for patients'safety and high standards of nursing care.

CHARACTERISTICS OF THE FLOW AND HEAT TRANSFER AROUND A WAVY CYLINDER (삼차원 원형주상체의 축방향 직경변화가 열.유동장에 미치는 영향)

  • Lee, Chang-Yeol;Seo, Jang-Hoon;Yoon, Hyun-Sik;Chun, Ho-Hwan
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2008.03a
    • /
    • pp.131-136
    • /
    • 2008
  • Three-dimensional characteristics of fluid flow and heat transfer around a wavy circular cylinder having sinusoidal variation in cross sectional area along the spanwise direction are numerically investigated using the immersed boundary method. The three different wavelengths of ${\pi}/4$, ${\pi}/3$ and ${\pi}/2$ and at the fixed wavy amplitude of 0.1 have been considered to investigate the effects of waviness on especially the forced convection heat transfer around a wavy cylinder when the Reynolds and Prandtl numbers are 300 and 0.71, respectively. The present computational results for a wavy cylinder are compared with those for a smooth cylinder. The time- and total surface-averaged Nusselt number for a wavy cylinder with is larger than that for a smooth cylinder, whereas that with ${\lambda}={\pi}/4$ and ${\pi}/3$ is smaller than that for a smooth cylinder. However, because the surface area exposed to heat transfer for a wavy cylinder is larger than that for a smooth cylinder, the total heat transfer rate for a wavy cylinder with different wavelengths of ${\lambda}={\pi}/4$, ${\pi}/3$ and ${\pi}/2$ is larger than that for a smooth cylinder.

  • PDF

A study on the V and X shpe defects in I $n_{0.53}$GaTEX>$_{0.47}$As/InTEX>$_{0.52}$AlTEX>$_{0.48}$As/InP P-HEMT structure grown by molecular beam epitaxy method (分子線에피택셜 方法으로 成長한 I $n_{0.53}$GaTEX>$_{0.47}$As/InTEX>$_{0.52}$AlTEX>$_{0.48}$As/InP P-HEMT 構造內의 V 및 X字形 缺陷에 關한 硏究)

  • 이해권;홍상기;김상기;노동원;이재진;편광의;박형무
    • Journal of the Korean Institute of Telematics and Electronics D
    • /
    • v.34D no.7
    • /
    • pp.56-61
    • /
    • 1997
  • I $n_{0.53}$G $a_{0.47}$As/I $n_{0.52}$A $l_{0.48}$As pseudomorphic high electron mobility transistor (P-HEMT) structures were grown on semi-insulating InP substrates by molecular beam epitzxy method. The hall effect measuremetn was used to measure the electrical properties and the photoluminescence (PL) measurement was used to measure the electrical properties and the photoluminescence(PL) measurement for optical propety. By the cross-sectional transmission electron microscopy (XTEM) investigation of the V and X shape defects including slip with angle of 60.deg. C and 120.deg. C to surface in the sampel, the defects formation mecahnism in the I $n_{0.52}$A $l_{0.48}$As epilayers on InP substrates could be explained with the different thermal expansion coefficients between I $n_{0.52}$A $l_{0.48}$As epilayers and InP substrate.d InP substrate.

  • PDF

Flow and Heat/Mass Transfer Characteristics of Arrays of Impingement Jets with Effusion Holes (유출홀이 설치된 배열 충돌제트의 유동 및 열전달 특성)

  • Lee, Dong-Ho;Yun, Pil-Hyeon;Jo, Hyeong-Hui
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.25 no.11
    • /
    • pp.1606-1615
    • /
    • 2001
  • The present study has been conducted to investigate heat/mass transfer characteristics on a target plate fur arrays of circular impingement jets with and without effusion holes. A naphthalene sublimation method is employed to determine local heat/mass transfer coefficients on the target plate. The effusion holes are located at the center of four injection holes in the injection plate where the spent air is discharged through the effusion hole after impingement on the target plate. For the array jet impingement without effusion holes, the array jets are injected into the crossflow formed by upstream spent air because the impinged jets must flow to the open exit. For small gap distances, heat/mass transfer coefficients without effusion holes are very non-uniform due to crossflow effects and re-entrainments of spent air. However, uniform distributions and enhanced values of heat/mass transfer coefficients are obtained by installing the effusion holes. For large gap distances, the crossflow has little influence on heat/mass transfer characteristics on the target palate due to the large cross-sectional open area between the injection and target plates. Therefore, the distributions and levels of heat/mass transfer coefficients are almost the same for both cases.

Brand Distribution Service and Its Effect on Customer Value

  • Margaretha, Margaretha;Halim, Rizal Edy
    • Journal of Distribution Science
    • /
    • v.16 no.1
    • /
    • pp.29-36
    • /
    • 2018
  • Purpose - The purpose of the research is to further explore the understanding of the nature of the brand distribution service (i.e., service brand) by undertaking a quantitative investigation. We focus on the role of customer's perception of service brand on the customer value creation process. Research design, data, and methodology - This study used single cross-sectional design and 137 airline passengers as respondents using a convenience random sampling. We distributed the online questionnaires by email address. The empirical setting for this research is airline service in Indonesia with a consideration that airline service has the useful context for this research as the service delivery process involve extensive customer interactions with the airline and its employees. We then analyzed the data using multiple regression (step-wise) method to fulfill the research objectives. Results - Using the step-wise regression method, the result shows that the influential factors to create customer value are cost and company image. The result suggests a company to improve its costs components and its company image in order to increase the customer value. Conclusions - The research shows that costs play a critical role, and completed with the company image to form the customer value variable. This shows that mostly customer formed their value based on costs they sacrificed. Mainly, this evaluation is monetary cost based, while Indonesian customers tend to have a high value for money demands.