http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Development of Ergonomic Balance Seat(e-BASE) Chair
Jae Hee Park,Seung Hee Kim,Min Uk Kim,Hanbum Jung,Young Soo Shim,Taehee Ryu 대한인간공학회 2013 大韓人間工學會誌 Vol.32 No.1
Objective: The aim of this study is to develop an ergonomic office chair that has an alarm function for the unbalanced sitting postures. Background: Contrary to expectation, it is reported that office workers sit on their chairs much more in unbalanced postures during daily work. Even though an office worker uses an ergonomically good-designed chair and begins their work in a good sitting posture, his/her posture is likely to shift to the unbalanced bad posture. Therefore, a posture alarm system would be very helpful in keeping office workers" good postures. Method: We developed a prototype chair with four load cells under a seat pan and one load cell beneath a backrest. Through some experiments, we set the criteria for unbalanced bad postures then implemented the criteria into the alarm system of the prototype chair. The chair called e-BASE chair could detect unbalance postures and show alarms for chair users. We also enhanced back support by developing a step-wised folding backrest. Results: The e-BASE chair showed better performance in interface pressure distributions and balanced posture ratio in VDT work. Conclusion: The ergonomic chair with posture alarm function(e-BASE chair) was developed. It showed better performance in seat pressure distribution and in keeping good posture during office work. Application: The posture alarm system and folding backrest can be applied to the new models of office chair.
Seat pressure and subjective comfort for varying sponge hardness and thickness
Jae Hee Park,Seung Hee Kim,Min Uk Kim,Hanbum Jung,Jung Hwan Lee 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.5
Objective: The aim of this study is to find the proper hardness and thickness of sponge using in office chairs. Background: The comfort of a chair mainly depends on the physical attributes of sponge on a seatpan. However, the optimal values of hardness and thickness are not selected from the view of seat pressure and comfort, but selected from subjective experiences of chair designers. Therefore, it is needed to find the relationship between comfort and sponge thickness and hardness. Method: Sponges varied in hardness with 3 levels and sponges varied in thickness with 5 levels were prepared. Ten subjects were seated on the sponges topped on a table adjustable in height. A body pressure measurement system with 36 x 36 sensors was used to collect pressure and contact area data. Results: In sponge thickness, it is recommended to use the sponge thicker than 50cm. In sponge hardness, there was no significant difference in the hardness range, 17-24kgf/cm3. Conclusion: The optimal sponge thickness and hardness can be decided with relating to sitting pressure and comfort. Application: The result data can be referred in the design of a seatpan.
Body pressure distributions of the varying sitting postures in office work
Jae Hee Park,Inseok Lee,Min Uk Kim,Seung Hee Kim,Hanbum Jung 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.5
Objective: The aim of this study is to find the ratio of right sitting posture in office workers' daily job. Background: Although office workers know the right sitting posture, their postures observed are likely to be biased improperly. These behaviors are caused by bad design of chair or by task variables. To find the problem of bad postures, a body pressure mat can be used. Method: Three office workers' seat and back pressure during daily work were measured by using two 36 x 36 pressure mats. Then the average pressure of right/left and posterior/anterior area and back pressure were used to categorizing good and bad postures. Results: Office workers pose properly in only 3.2% of daily work. Most of time, 81.5%, their back were separated from seat back. Also they bent and twisted their back improperly to perform tasks. Conclusion: The result showed that office works pose improperly during work. To maintain the proper posture, ergonomic design in seat pressure is needed. Application: The evaluation method used in this study can be applied to evaluate chairs.
Choi, Hyejin,Jeong, Kwangsik,Chae, Jimin,Park, Hanbum,Baeck, Juheyuck,Kim, Tae Hyeon,Song, Jae Yong,Park, Jaehun,Jeong, Kwang-Ho,Cho, Mann-Ho Elsevier 2018 Nano energy Vol.47 No.-
<P><B>Abstract</B></P> <P>A comprehensive understanding of the nano-structural effects that cause reduction in thermal conductivity represents important challenges for the development of thermoelectric materials with an improved figure of merit ZT. Bismuth telluride (Bi<SUB>2</SUB>Te<SUB>3</SUB>)-based thermoelectric materials exhibit very low levels of thermal conductivity. In this study, a Te crystal-embedded Bi<SUB>2</SUB>Te<SUB>3</SUB> (Te–Bi<SUB>2</SUB>Te<SUB>3</SUB>) thin film was formed by establishing a specific annealing temperature for a Te-rich Bi/Te multilayered structure. Modulations in structure and composition were observed at the boundaries between the two phases of Te and Bi<SUB>2</SUB>Te<SUB>3</SUB>. Furthermore, the samples contained regularly shaped nanometer-scale Bi<SUB>2</SUB>Te<SUB>3</SUB> single grains. Therefore, we obtained a dramatic ZT value of 2.27 (+ 0.04, − 0.08) at 375 K from the Te–Bi<SUB>2</SUB>Te<SUB>3</SUB> thin film. Finally, we confirmed that interface phonon scattering between the Te–Bi<SUB>2</SUB>Te<SUB>3</SUB> boundaries plays an important role in inter-grain phonon transport, which results in a reduction in the lattice thermal conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Te-Bi<SUB>2</SUB>Te<SUB>3</SUB> nano-grain structure is synthesized by multi-layer deposition and simple annealing process. </LI> <LI> Obtain a dramatic zT value of 2.27 (+ 0.04 − 0.08) at 375 K in Te embedded-Bi<SUB>2</SUB>Te<SUB>3</SUB> thin film. </LI> <LI> The Te-Bi<SUB>2</SUB>Te<SUB>3</SUB> heterojunction has high electrical conductivity and low thermal conductivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Jeong, Jaehun,Choi, Yoon-Ho,Jeong, Kwangsik,Park, Hanbum,Kim, Dasol,Cho, Mann-Ho American Physical Society 2018 Physical Review B Vol.97 No.7
<P>The dependence of the optical and electrical properties of two-dimensional transition metal dichalcogenides on the number of layers has garnered significant interest. In particular, the indirect-to-direct band gap transition and the resulting changes, such as improved quantum yield, have been widely studied. However, an experimental investigation of the dependence of the optical transition for a wide range of photon energies is still lacking. Here, we report the broadband optical response of large-area MoSe2 grown from monolayer to pentalayer thicknesses by molecular beam epitaxy, for photon energies in the 0.9-5.5 eV range. We observed a dramatic evolution of the absorption spectrum that depends on the number of layers. Using the density functional theory, we show that this feature is related to a change in the energy and geometric shape of the band structure at the. point in the Brillouin zone. The dependence of these optical properties on the number of layers yields insights into the underlying physics and is promising for photonic and optoelectronic applications.</P>
Kim, Dae-Kyoung,Chae, Jimin,Hong, Seok-Bo,Park, Hanbum,Jeong, Kwang-Sik,Park, Hyun-Woo,Kwon, Se-Ra,Chung, Kwun-Bum,Cho, Mann-Ho The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.48
<P>We evaluated the change in the chemical structure between dielectrics (AlOx and HfOx) grown by atomic layer deposition (ALD) and oxidized black phosphorus (BP), as a function of air exposure time. Chemical and structural analyses of the oxidized phosphorus species (PxOy) were performed using atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, first-principles density functional theory calculations, and the electrical characteristics of field-effect transistors (FETs). Based on the combined experiments and theoretical investigations, we clearly show that oxidized phosphorus species (PxOy, until exposed for 24 h) are significantly decreased (self-reduction) during the ALD of AlOx. In particular, the field effect characteristics of a FET device based on Al2O3/AlOx/oxidized BP improved significantly with enhanced electrical properties, a mobility of ∼253 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and an on-off ratio of ∼10<SUP>5</SUP>, compared to those of HfO2/HfOx/oxidized BP with a mobility of ∼97 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and an on-off ratio of ∼10<SUP>3</SUP>-10<SUP>4</SUP>. These distinct differences result from a significantly decreased interface trap density (<I>D</I>it ∼ 10<SUP>11</SUP> cm<SUP>−2</SUP> eV<SUP>−1</SUP>) and subthreshold gate swing (SS ∼ 270 mV dec<SUP>−1</SUP>) in the BP device caused by the formation of stable energy states at the AlOx/oxidized BP interface, even with BP oxidized by air exposure.</P>