몽골 울란바토르시 게르촌 주택의 겨울철 실내 초미세먼지(PM 2.5 ) 농도의 시간적 변이

이보람(Boram Lee),이지영(Jiyoung Lee),장예림(Yelim Jang),김윤지(Yoonjee Kim),하헌성(Hunsung Ha),이우석(Wooseok Lee),최우석(Wooseok Choe),김규성(Kyusung Kim),우철운(Cheolwoon Woo),Chimedsuren Ochir,이기영(Kiyoung Lee) 한국환경보건학회 2018 한국환경보건학회지 Vol.44 No.1

Objectives: In Mongolian housing, they use coal as a fuel for indoor heating and cooking. The combustion of coal releases particulate matter, which can affect indoor air quality. The purpose of this study was to analyze the concentrations of indoor PM 2.5 Methods: In this study, indoor PM 2.5 concentrations, temperature and humidity in houses were measured by a real-time PM monitor, while the time activity patternsof the residents were also observed. Results: The correlation between factors that may affect the indoor air quality was analyzed.The indoor PM 2.5 concentrations were 178.4±152.7 µg/m 3 (n=37). Five types of indoor PM 2.5 concentrations have been classified, which were associated with indoor activity. The stove type, fuel types and indoor activities such as cleaning, cooking and opening the stoves were not significantly associated with indoor PM 2.5 levels. Conclusions: Further study is needed to determine the effect of stove type through 24hours of indoor air quality monitoring.

Small-Cell 기지국 시스템을 위한 2.6 GHz GaN-HEMT Doherty 전력증폭기 집적회로 설계

이휘섭(Hwiseob Lee),임원섭(Wonseob Lim),강현욱(Hyunuk Kang),이우석(Wooseok Lee),이형준(Hyoungjun Lee),윤정상(Jeongsang Yoon),이동우(Dongwoo Lee),양영구(Youngoo Yang) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.2

본 논문에서는 2.6 GHz에서 동작하는 Doherty 전력증폭기 집적회로를 설계 및 제작하여 평균 전력에서의 효율을 개선하였다. Small-cell 기지국 시스템에 적합하도록 전력 밀도가 높은 GaN-HEMT 공정을 사용하여 설계하였으며, 제작된 Doherty 전력증폭기 집적회로를 QFN 패키지 내부에 수용하여 시스템 적용에 용이하도록 하였다. 제작된 GaN-HEMT Doherty 전력증폭기 집적회로는 10 MHz의 대역폭 및 6.5 dB의 PAPR 특성을 갖는 2.6 GHz LTE 신호에 대하여 평균 전력 33.9 dBm에서 15.8 dB의 전력 이득, 43.0%의 효율 및 —30.0 dBc의 ACLR 특성을 나타낸다. This paper presents a 2.6 GHz Doherty power amplifier IC to enhance the back-off efficiency. In order to apply to small-cell base stations, the Doherty power amplifier was fabricated using GaN-HEMT process for high power density. In addition, the implemented Doherty power amplifier was mounted on a QFN package. The implemented GaN-HEMT Doherty power amplifier was measured using LTE downlink signal with 10 MHz bandwidth and 6.5 dB PAPR for verification. A power gain of 15.8 dB, a drain efficiency of 43.0 %, and an ACLR of —30.0 dBc were obtained at an average output power level of 33.9 dBm.

Distribution of phthalate esters in air, water, sediments, and fish in the Asan Lake of Korea

Lee, Young-Min,Lee, Jung-Eun,Choe, Wooseok,Kim, Taeyeon,Lee, Ji-Young,Kho, Younglim,Choi, Kyungho,Zoh, Kyung-Duk Elsevier 2019 Environment international Vol.126 No.-

<P><B>Abstract</B></P> <P>Phthalate esters (PEs) are the most commonly used plasticizers and one of the endocrine disrupting chemicals (EDCs) which are extensively present in various environment. Therefore, it is important to examine the levels and distribution of phthalates in multimedia environment. This study investigated the seasonal and spatial variation of 14 PEs in air, water, sediments, and fish in the Asan Lake. Asan Lake is one of the largest artificial lakes in Korea, and is surrounded by industrial complex and farmlands. The PEs were found to be present throughout the study area. The mean concentration of total PEs (∑<SUB>14</SUB> PEs) was 3.92–33.09 ng/m<SUP>3</SUP> in air, not detected (n.d.)-2.29 μg/L in water, 3.6–8973 μg/kg dry weight (dw) in sediment, and n.d.-1081 μg/kg dw in fish, respectively. The most frequently detected phthalate in the samples was di(2-ethylhexyl) phthalate (DEHP), and followed by di-n-butyl phthalate (DBP). The concentrations of PEs in water and sediment samples tended to decrease moving downstream of Asan Lake. Bioaccumulation of PEs showed that benthic feeding fish such as crucian carp or skygager contained higher levels of DEHP. Partitioning of DEHP and DBP between water and sediment was calculated using paired sediment/water samples and fugacity fraction (<I>ff</I>). High <I>ff</I> value (<I>ff</I> = 0.89 ± 0.1) of DBP and low <I>ff</I> value of DEHP (<I>ff</I> = 0.24 ± 0.1) confirmed that DEHP is the most abundant PEs in the sediment, and DBP is the second most abundant PEs except DEHP in water. Our results can provide important information of the distribution and behavior of PEs in the lake environment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 14 phthalates were measured in air, water, sediment, and fish in Asan lake areas. </LI> <LI> Among phthalates, 2. DEHP and DBP were most frequently detected in all media. </LI> <LI> Phthalate levels in water and sediment increased moving downstream of the lake. </LI> <LI> Benthic feeding fish such as crucian carp or skygazer contained high level of DEHP. </LI> <LI> Sediment was a sink of DEHP and the potential secondary source of DBP in the lake. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The distributed characteristics of fish schools on the Marine Ranching Area around the Ulleung-do

Wooseok Oh,Geunchang Park,Euna Yoon,Yongseok Choi,Byungho Lee,Sungho Suh,Inwoo Han,Doojin Hwang,Kyounghoon Lee 한국수산해양기술학회(구 한국어업기술학회) 2018 한국수산해양기술학회 학술발표대회 Vol.2018 No.11

Retarding Crystallization during Facile Single Coating of NaCl-Incorporated Precursor Solution for Efficient Large-Area Uniform Perovskite Solar Cells

Lee, Hongseuk,Kim, Areum,Kwon, Hyeok-Chan,Yang, Wooseok,Oh, Yunjung,Lee, Daehee,Moon, Jooho American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.43

<P>We demonstrated crystallization retardation of CH3NH3PbI3 thin film during single coating of precursor solution by simple addition of NaCl. NaCl was codissolved into a precursor mixture solution containing PbI2 and methylammonium iodide (MAI). Dissolved NaCl interacted with the PbI2 in solution and produced a stable intermediate phase, which was converted to a full coverage uniform perovskite absorber layer via reaction with MAI during a single spin-coating. The resulting planar-structure perovskite solar cell made from NaCl-supplemented precursor solution showed a 48% improvement in power conversion efficiency (PCE) (maximum value 15.16%) over the device fabricated without the additive. Our NaCl-supplemented single coating represents an easy approach to effectively obtain highly reproducible uniform performance at an overall position in 5 cm x 5 cm sized cells (divided into 20 subcells with an active area of 0.06 cm(2)) with average PCEs of 12.00 +/- 0.48%.</P>

Improvement of facial asymmetry using high intensity focused ultrasound (HIFU) in a Ramsay Hunt syndrome patient

( Wooseok Jeong ),( Woojung Jin ),( Seunghyun Moon ),( Taekgeun Lee ),( Jongkeun Seo ),( Taegwang Kwon ),( Sookkyung Lee ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.1

Ramsay Hunt syndrome (herpes zoster oticus) is characterized by vesicles on the pinna, otalgia, facial nerve palsy and hearing loss. The most common clinical appearance was vesicular eruptions and facial nerve palsy including change in nasolabial fold and location of the lip. Although early systemic steroid is administered, facial nerve palsy persists in more than 50% of the patients. High intensity focused ultrasound (HIFU) has become one of the most popular non-invasive technologies for skin tightening and face lifting. HIFU is a highly precise medical procedure that delivers high-intensity focused ultrasound to the deeper layers of the skin. A 42-year-old man who had been diagnosed as Ramsay Hunt syndrome 4 years ago presented with facial asymmetry due to left facial palsy. Left eyebrow, left eyelid and left angle of mouth were sagging down. 2 months after a single session of HIFU treatment, left eyebrow and left angle of mouth were lifting. The patient was satisfied with improvement of facial asymmetry. We report the application of HIFU as a treatment tool to the face in a patient with facial asymmetry due to left facial palsy by Ramsay Hunt syndrome.

Long-term air-stable Au doping of graphene by layer-by-layer assembly with graphene oxide for flexible transparent electrodes

Lee, Su Jin,Lim, Yi Rang,Ji, Seulgi,Kim, Seong Ku,Yoon, Yeoheung,Song, Wooseok,Myung, Sung,Lim, Jongsun,An, Ki-Seok,Park, Jin-Seong,Lee, Sun Sook Elsevier 2018 Carbon Vol.126 No.-

<P><B>Abstract</B></P> <P>In order to realize the most suitable hybrid structure for air-stable graphene-based transparent and flexible electrodes, we systematically compared graphene oxide (GO)/Au/graphene and graphene/Au/GO hybrid films fabricated by layer-by-layer assembly. The sheet resistance of graphene/Au/GO was proportional to the concentration of AuCl<SUB>3</SUB> (1–5 mg/ml), which can be understood by a significant blue-shift in the G-band associated with the phonon stiffening. The size and density of formed Au nanoparticles strongly influenced their reduction reaction, which is a crucial factor for maximizing the doping effects. The optimized optical transmittance and sheet resistance of GO/Au/graphene were 94.9% and 198 ± 29 Ohm/sq, respectively. Furthermore, the hybrid films revealed stable doping effects (sheet resistance variation: 23–55%) against ambient conditions after 1 month. The variation in sheet resistance for GO/Au/graphene hybrid films corresponds to 30% with a bending radius of 10 mm after repeated bending tests (bending cycles of 10<SUP>5</SUP>).</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhance Charge Cycle Efficiency of Lead-acid Battery using Solar Power System

Wooseok Lee(이우석),Hanmil Park(박한밀),Eunsonn Justin Shin(신은수) 적정기술학회 2018 적정기술학회지(Journal of Appropriate Technology) Vol.4 No.2

In developing countries, many areas are not supplied with electricity due to lack of electric power infrastructure, and many others are suffering from unstable power quality and frequent power outages. As an alternative, power supply using renewable energy, such as solar, wind, and small hydro power, is being activated. Among these, the most widely used source is photovoltaic power generation system, which is easy to install and maintain. In developed countries where power supply is smooth, grid connected photovoltaic systems that use conventional electricity together are generally used for the purpose of reducing electricity bill. However, in developing countries, because conventional electricity supply is unstable, independent solar power generation systems using batteries are mainly used. Among these, a solar panel is a semi-permanent product that can be used for more than 20 years, whereas a typical battery is a consumable with a maximum life span of less than five years, accounting for most maintenance cost of solar power systems. In addition, in the case of a lead storage cell, which is readily available in developing countries and therefore is most widely used, lifespan has been drastically reduced depending on environmental conditions such as pre-charge method, temperature, and humidity, which frequently makes it replaced in six months. For these reasons, management methods to extend lifespan of lead storage cell have become an important research topic. In this study, a voltage level was set as a measure value to identify and manage the characteristics of charging and discharging of lead storage batteries, and standardized discharge curves were created using LED lamps that consume the most stable power. Based on this, the discharging characteristics for different kinds of DC and AC products were identified. Also, the proper isolation voltage level to extend the battery lifespan was verified. The study will be used to design an optimized solar power system along with the further study on charging efficiency of solar power systems in developing countries.

Optimized Current of the Peaking Amplifier for Two-Stage Doherty Power Amplifier

Lee, Hwiseob,Kwon, Jinhee,Lim, Wonseob,Lee, Wooseok,Kang, Hyunuk,Hwang, Keum Cheol,Lee, Kang-Yoon,Park, Cheon-seok,Yang, Youngoo Professional Technical Group on Microwace Theory a 2017 IEEE Transactions on Microwave Theory and Techniqu Vol. No.

<P>This paper presents a method of improving efficiency for the two-stage Doherty power amplifier (DPA) using the optimized current of the peaking amplifier. The DPA has a two-stage structure for both the carrier and peaking amplifiers. The first stage of the peaking amplifier has an adjusted bias condition for a near Class-B operation, while the first stage of the carrier amplifier has a higher Class-AB operation. The gain expansion of the first stage due to its lower gate bias helps the second stage of the peaking amplifier to be biased for light Class-C operation and to have steeper turn-ON characteristics, which leads higher peak output power and higher back-off efficiency. The two-stage DPA was designed for the 2.655-GHz band. Using a downlink long-term evolution signal with a signal bandwidth of 10 MHz and a peak-to-average power ratio of 6.5 dB, the overall power gain of 25 dB and a peak output power of 54.2 dBm are experimentally obtained. Using an optimized shape of the peaking amplifier's current, a drain efficiency (DE) of 53% and an adjacent channel leakage power ratio of -30 dBc were obtained at an average output power of 47.8 dBm. A DE of 56.8% and an adjacent channel leakage power ratio of -25 dBc were also obtained at an average output power of 49.5 dBm.</P>

A clinical and histopathologic study of 24 cases of lichen striatus

( Wooseok Jeong ),( Taekgeun Lee ),( Seunghyun Moon ),( Hyun Hwangbo ),( Sewon Jung ),( Sookkyung Lee ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.2

Background: Lichen striatus(LS) is a self-limiting inflammatory condition of unknown etiology in which the lesions follow the lines of Blaschko. LS can usually be identified by clinical history and histopathology of typical lesions. However, the histopathologic features are diverse and have not been studied sufficiently yet. Objectives: To investigate the histopathologic characteristics according to the clinical manifestation of LS: age of patients, duration, site, symptom, color and morphology of the lesions. Methods: We have reviewed the medical records, photographs and histopathologic slides of 24 patients diagnosed with LS at our clinic between 2005 and 2015. Results: Under the age of 18, the number of patients with histopathologic findings of spongiosis was significantly increased. In the group of more than 6 months duration of the lesions, the number of patients with perieccrine infiltration was significantly increased. If the lesions were pruritic or tingling sensed, the number of patients with acanthosis, lichenoid infiltration and perieccrine infiltration were significantly increased. There were no statistically significant histopathologic differences according to the color and morphology of the lesions. Conclusion: The histopathologic features of LS are variable and may be nonspecific, but there are distinctive microscopic findings according to the age of the patients, duration and symptom of the lesions.