부산대학교 도서관
검색
통합검색
소장자료
학술논문
전자저널
학술DB
전자책
교내접속
OFF
로그인
커뮤니티
공지 및 행사
게시판문의
자주묻는질문
전화/이메일 문의
도서관 일정
영문 바로가기
로그인
자료검색
통합검색
소장자료
학술논문
전자저널
학술DB
전자책
온라인강좌
컬렉션
인기도서
신착도서
책 읽는 대학
테마도서
교수저작물 컬렉션
PNU 생산자료
도서관 소식지
연구·학습지원
연구지원
논문작성지원
연구정보가이드
이용교육
학습정보가이드
수업교재정보
자료이용안내
대출/반납
희망도서 신청
원문복사/상호대차
소장학술지 원문제공
외국학술지지원센터
협력기관
자료배달
SDI서비스
교외접속
시설이용안내
개관시간/층별
이용자별안내
열람실
그룹스터디룸
매체 제작/편집실
시설대관
PC/Wi-Fi/모바일
출력/복사/스캔
도서관소개
사명과 비전
역대 도서관장
연혁
조직 및 부서
통계
규정/운영세칙
오시는길
기증/기부
커뮤니티
공지 & 행사
게시판 문의
자주묻는 질문
전화/이메일 문의
도서관 일정
My Library
내서재
대출중인 도서
연체/제재
예약도서
원문복사(상호대차)
이용교육
정보 변경
전체메뉴 열기
로그인하세요
부산대학교 도서관
자료검색
통합검색
소장자료
학술논문
전자저널
학술DB
전자책
온라인강좌
컬렉션
인기도서
신착도서
책 읽는 대학
테마도서
교수저작물 컬렉션
PNU 생산자료
도서관 소식지
연구·학습지원
연구지원
논문작성지원
연구정보가이드
이용교육
학습정보가이드
수업교재정보
자료이용안내
대출/반납
희망도서 신청
원문복사/상호대차
소장학술지 원문제공
외국학술지지원센터
협력기관
자료배달
SDI서비스
교외접속
시설이용안내
개관시간/층별
이용자별안내
열람실
그룹스터디룸
매체 제작/편집실
시설대관
PC/Wi-Fi/모바일
출력/복사/스캔
도서관소개
사명과 비전
역대 도서관장
연혁
조직 및 부서
통계
규정/운영세칙
오시는길
기증/기부
커뮤니티
공지 & 행사
게시판 문의
자주묻는 질문
전화/이메일 문의
도서관 일정
My Library
내서재
대출중인 도서
연체/제재
예약도서
원문복사(상호대차)
이용교육
정보 변경
clear
교내접속
OFF
영문 바로가기
Home
통합검색
학술논문
학술논문
arrow_drop_down
통합검색
ISSN
논문명
저널명
저자명
다국어
세부검색
히라가나
가타가나
독일,프랑스,스페인
그리스
라틴
러시아
로마자
한글고어
단위기호
학술기호
타이어
몽골어
o
ㅋ
ㄱ
ㅅ
ㅈ
ㅌ
ㄷ
촉
ㄴ
ㅎ
ㅂ
ㅃ
ㅁ
야
ㄹ
와
ㅏ
あ
a
ぁ
か
ka
が
ga
さ
sa
ざ
za
た
ta
だ
da
な
na
は
ha
ば
ba
ぱ
pa
ま
ma
や
ya
ゃ
lya
ら
ra
わ
wa
ゎ
lwa
ん
n
l
い
i
ぃ
き
ki
ぎ
gi
し
si
じ
zi
ち
ti
ぢ
di
に
ni
ひ
hi
び
bi
ぴ
pi
み
mi
り
ri
ㅜ
う
u
ぅ
く
ku
ぐ
gu
す
su
ず
zu
つ
tu
づ
du
っ
ぬ
nu
ふ
hu
ぶ
bu
ぷ
pu
む
mu
ゆ
yu
ゅ
lyu
る
ru
ㅔ
え
e
ぇ
け
ke
げ
ge
せ
se
ぜ
ze
て
te
で
de
ね
ne
へ
he
べ
be
ぺ
pe
め
me
れ
re
ㅗ
お
o
ぉ
こ
ko
ご
go
そ
so
ぞ
zo
と
to
ど
do
の
no
ほ
ho
ぼ
bo
ぽ
po
も
mo
よ
yo
ょ
lyo
ろ
ro
を
wo
o
ㅋ
ㄱ
ㅅ
ㅈ
ㅌ
ㄷ
촉
ㄴ
ㅎ
ㅂ
ㅃ
ㅁ
야
ㄹ
와
ㅏ
ア
a
ァ
カ
ka
ガ
ga
サ
sa
ザ
za
タ
ta
ダ
da
ナ
na
ハ
ha
バ
ba
パ
pa
マ
ma
ヤ
ya
ャ
lya
ラ
ra
ワ
wa
ヮ
lwa
ン
n
l
イ
i
ィ
キ
ki
ギ
gi
シ
si
ジ
zi
チ
ti
ヂ
di
ニ
ni
ヒ
hi
ビ
bi
ピ
pi
ミ
mi
リ
ri
ㅜ
ウ
u
ゥ
ク
ku
グ
gu
ス
su
ズ
zu
ツ
tu
ヅ
du
ッ
ヌ
nu
フ
hu
ブ
bu
プ
pu
ム
mu
ユ
yu
ュ
lyu
ル
ru
ヴ
vu
ㅔ
エ
e
ェ
ケ
ke
ゲ
ge
セ
se
ゼ
ze
テ
te
デ
de
ネ
ne
ヘ
he
ベ
be
ぺ
pe
メ
me
レ
re
ㅗ
オ
o
ォ
コ
ko
ゴ
go
ソ
so
ゾ
zo
ト
to
ド
do
ノ
no
ホ
ho
ボ
bo
ポ
po
モ
mo
ヨ
yo
ョ
lyo
ロ
ro
ヲ
wo
ー
ー
독일어
ä
Ä
ö
Ö
ü
Ü
ß
프랑스어
á
à
Á
À
é
è
É
È
ç
Ç
ê
스페인어
à
á
Á
é
É
í
Í
Ó
ó
Ú
ú
Ñ
ñ
ä
Ä
Α
Β
Γ
Δ
Ε
Ζ
Η
Θ
Ι
Κ
Λ
Μ
Ν
Ξ
Ο
Π
Ρ
Σ
Τ
Υ
Φ
Χ
Ψ
Ω
α
β
γ
δ
ε
ζ
η
θ
ι
κ
λ
μ
ν
ξ
ο
π
ρ
ς
σ
τ
υ
φ
χ
ψ
ω
À
Á
Â
Ã
Ä
Å
Æ
Ç
È
É
Ê
Ë
Ì
Í
Î
Ï
Ð
Ñ
Ò
Ó
Ô
Õ
Ö
Ø
Ù
Ú
Û
Ü
Ý
Þ
ß
à
á
â
ã
ä
å
æ
ç
è
é
ê
ë
ì
í
î
ï
ð
ñ
ò
ó
ô
õ
ö
ø
ù
ú
û
ü
ý
þ
ÿ
А
Б
В
Г
Д
Е
Ё
Ж
З
И
Й
К
Л
М
Н
О
П
Р
С
Т
У
Ф
Х
Ц
Ч
Ш
Щ
Ъ
Ы
Ь
Э
Ю
Я
а
б
в
г
д
е
ё
ж
з
и
й
к
л
м
н
о
п
р
с
т
у
ф
х
ц
ч
ш
щ
ъ
ы
ь
э
ю
я
ⅰ
ⅱ
ⅲ
ⅳ
ⅴ
ⅵ
ⅶ
ⅷ
ⅸ
ⅹ
Ⅰ
Ⅱ
Ⅲ
Ⅳ
Ⅴ
Ⅵ
Ⅶ
Ⅷ
Ⅸ
Ⅹ
ㅥ
ㅦ
ㅧ
ㅨ
ㅩ
ㅪ
ㅫ
ㅬ
ㅭ
ㅮ
ㅯ
ㅰ
ㅱ
ㅲ
ㅳ
ㅴ
ㅵ
ㅶ
ㅷ
ㅸ
ㅹ
ㅺ
ㅻ
ㅼ
ㅽ
ㅾ
ㅿ
ㆀ
ㆁ
ㆂ
ㆃ
ㆄ
ㆅ
ㆆ
ㆇ
ㆈ
ㆉ
ㆊ
ㆋ
ㆌ
ㆍ
ㆎ
′
″
℃
Å
¢
£
¥
¤
℉
‰
$
%
F
₩
㎕
㎖
㎗
ℓ
㎘
㏄
㎣
㎤
㎥
㎦
㎙
㎚
㎛
㎜
㎝
㎞
㎟
㎠
㎡
㎢
㏊
㎍
㎎
㎏
㏏
㎈
㎉
㏈
㎧
㎨
㎰
㎱
㎲
㎳
㎴
㎵
㎶
㎷
㎸
㎹
㎀
㎁
㎂
㎃
㎄
㎺
㎻
㎽
㎾
㎿
㎐
㎑
㎒
㎓
㎔
Ω
㏀
㏁
㎊
㎋
㎌
㏖
㏅
㎭
㎮
㎯
㏛
㎩
㎪
㎫
㎬
㏝
㏐
㏓
㏃
㏉
㏜
㏆
±
×
÷
≠
≤
≥
∞
∴
∠
⊥
⌒
∂
∇
≡
≒
≪
≫
√
∽
∝
∵
∫
∬
∈
∋
⊆
⊇
⊂
⊃
∪
∩
∧
∨
¬
⇒
⇔
∀
∃
∮
∑
∏
+
-
<
=
>
ก
ข
ฃ
ค
ฅ
ฆ
ง
จ
ฉ
ช
ซ
ฌ
ญ
ฎ
ฏ
ฐ
ฑ
ฒ
ณ
ด
ต
ถ
ท
ธ
น
บ
ป
ผ
ฝ
พ
ฟ
ภ
ม
ย
ร
ฤ
ล
ฦ
ว
ศ
ษ
ส
ห
ฬ
อ
ฮ
ฯ
ะ
ั
า
ำ
ิ
ี
ึ
ื
ุ
ู
ฺ
฿
เ
แ
โ
ใ
ไ
ๅ
ๆ
็
่
้
๊
๋
์
ํ
๎
๏
᠀
᠁
᠂
᠃
᠄
᠅
᠆
᠇
᠈
᠉
᠊
᠐
᠑
᠒
᠓
᠔
᠕
᠖
᠗
᠘
᠙
ᠠ
ᠡ
ᠢ
ᠣ
ᠤ
ᠥ
ᠦ
ᠧ
ᠨ
ᠩ
ᠪ
ᠫ
ᠬ
ᠭ
ᠮ
ᠯ
ᠰ
ᠱ
ᠲ
ᠳ
ᠴ
ᠵ
ᠶ
ᠷ
ᠸ
ᠹ
ᠺ
ᠻ
ᠼ
ᠽ
ᠾ
ᠿ
ᡀ
ᡁ
ᡂ
ᡃ
ᡄ
ᡅ
ᡆ
ᡇ
ᡈ
ᡉ
ᡊ
ᡋ
ᡌ
ᡍ
ᡎ
ᡏ
발행년
-
(예 : 2010-2015)
'학술논문'
에서 검색결과
286
건 | 목록
1~10
전체선택
내보내기
Relevance
arrow_drop_down
Relevance
DateNewest
Date Oldest
10
arrow_drop_down
5
10
20
30
40
50
format_list_bulleted
format_list_bulleted
E-mail
EndNote
RefWorks
The influence of organizational caring on mobile phone addiction in undergraduate nursing students: The chain mediating role of perceived stress and self-control
Academic Journal
Zheng, W.
;
Fang, J.
;
Tan, Y.
;
Chen, W.
;
Li, N.
;
Huang, J.
;
Wang, L.
;
Wang, M.
;
Feng, X.
;
Heng, C.
In:
Heliyon
. (Heliyon, 30 September 2024, 10(18))
Full Text (ScienceDirect 종량제)
Full Text (ScienceDirect O/A)
Web of Science
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
Performance Analysis of Combined Medical Waste-Waste Tire Resource Utilization System Based on Gasification and Pyrolysis
Academic Journal
Fuyuan, F.
;
Tongyu, L.
;
Bo, L.
;
Heng, C.
;
Peiyuan, P.
;
Gang, X.
;
Tong, L.
In:
Power Generation Technology
. (Power Generation Technology, 31 August 2024, 45(4):611-621)
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
Restorabite™: Phase II trial of jaw stretching exercises using a novel device for patients with trismus following head and neck cancer
Academic Journal
Charters, E.
;
Cheng, K.
;
Dunn, M.
;
Heng, C.
;
Loy, J.
;
Ricketts, V.
;
Luo, A.
;
Aung, Y.M.
;
Howes, D.
;
Manzie, T.
;
Clark, J.
;
Lewin, W.
;
Wan, B.
In:
International Journal of Cancer
. (International Journal of Cancer, 15 August 2024, 155(4):731-741)
Full Text (Wiley Journals)
Full Text (Wiley-DB)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
Research on Support Technology of a Soil-Rock Combination Deep Excavation in Qingdao
Academic Journal
Zhang, W.
;
Heng, C.
;
Xu, C.
;
Mao, L.
;
Zhou, Z.
In:
KSCE Journal of Civil Engineering
. (KSCE Journal of Civil Engineering, August 2024, 28(8):3208-3223)
Full Text (ScienceDirect 종량제)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
Integrated Waverider Forebody/Inlet Fusion Method Based on Discrete Point Cloud Reconstruction
Academic Journal
Liu, Z.
;
Luo, M.
;
Zhang, J.
;
Heng, C.
;
Yin, G.
In:
Aerospace
. (Aerospace, July 2024, 11(7))
Full Text (ProQuest Central)
Full Text (Gale Academic Onefile)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
A 26.6–119.3-μW 101.9-dB SNR Direct Digitization Bio-Impedance Readout IC
Academic Journal
Zhang, T.
;
Son, H.
;
Zhao, J.
;
Heng, C.
;
Gao, Y.
IEEE Journal of Solid-State Circuits IEEE J. Solid-State Circuits Solid-State Circuits, IEEE Journal of. 58(9):2619-2631 Sep, 2023
Full Text (IEEE)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
The mediating role of psychological capital on the relationship between perceived stress and self-directed learning ability in nursing students
Academic Journal
Yang, D.
;
Zhang, Q.
;
Yan, Y.
;
Zheng, W.
;
Fang, J.
;
Wen, H.
;
Li, N.
;
Wang, X.
;
Chen, W.
;
Liu, Z.
;
Feng, X.
;
Wang, M.
;
Heng, C.
In:
BMC Nursing
. (BMC Nursing, December 2024, 23(1))
EBSCOHost PDF
Full Text (ProQuest Central)
Full Text (Gale Academic Onefile)
Open Access (BioMed Central)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
Effect of raw material, moisture and high-temperature tertiary air on a coal gasifier for cement precalciation
Academic Journal
Leyu, Z.
;
Qingqing, C.
;
Xiaolin, W.
;
Heng, C.
;
Sen, L.
In:
Fuel Processing Technology
. (Fuel Processing Technology, 15 October 2024, 262)
Full Text (ScienceDirect 종량제)
Full Text (ScienceDirect O/A)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
A 107 pJ/b TX 260 pJ/b RX Ultralow-Power MEMS-Based Transceiver With Wake-Up in ISM-Bands for IoT Applications
Academic Journal
Tang, K.
;
Yang, C.
;
Guo, Y.
;
Wang, N.
;
Zhu, Y.
;
Zhang, Y.
;
Ng, E.J.
;
Lee, J.E.
;
Fang, Z.
;
Wang, W.
;
Jiang, H.
;
Heng, C.
;
Zheng, Y.
IEEE Journal of Solid-State Circuits IEEE J. Solid-State Circuits Solid-State Circuits, IEEE Journal of. 58(5):1337-1349 May, 2023
Full Text (IEEE)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
Coupling relationship between molecule structure at silica/silicone gel interfaces and ionic conductivity in polymer composites
Academic Journal
Lin, Y.
;
Dong, L.
;
Heng, C.
;
Chen, K.
;
Liu, Y.
In:
Composites Science and Technology
. (Composites Science and Technology, 12 April 2024, 249)
Full Text (ScienceDirect 종량제)
Web of Science
JCR 저널정보
Scopus
Find it@PNU
playlist_add_check
요약보기
open_in_browser
내보내기
E-mail
EndNote
RefWorks
1
2
3
4
…
17
18
19
20
다음
검색 결과 제한하기
arrow_forward
제한된 항목
[AR] Heng, C.
clear
발행연도 제한
-
재검색
학술DB(Database Provider)
Scopus®
(208)
IEEE Xplore Digital Library
(43)
Science Citation Index Expanded
(14)
Academic Search Complete
(5)
Complementary Index
(4)
Social Sciences Citation Index
(4)
Business Source Complete
(2)
Gale Academic OneFile
(2)
ScienceDirect
(2)
Supplemental Index
(2)
Gale General OneFile
(1)
add
remove
더보기
zoom_in
재검색
저널명(출판물, Title)
ieee transactions on nuclear science
(11)
ieee journal of solid-state circuits, solid-state circuits, ieee journal of, ieee j. solid-state circuits
(10)
value in health
(10)
ieee transactions on biomedical circuits and systems, biomedical circuits and systems, ieee transactions on, ieee trans. biomed. circuits syst.
(7)
dianli xitong zidonghue/automation of electric power systems
(6)
ieee transactions on circuits and systems ii: express briefs, circuits and systems ii: express briefs, ieee transactions on, ieee trans. circuits syst. ii
(5)
oncogene
(5)
ieee microwave and wireless components letters, microwave and wireless components letters, ieee, ieee microw. wireless compon. lett.
(4)
malaria journal
(4)
applied microbiology and biotechnology
(3)
applied surface science
(3)
ieee transactions on circuits and systems i: regular papers, circuits and systems i: regular papers, ieee transactions on, ieee trans. circuits syst. i
(3)
ieee transactions on very large scale integration (vlsi) systems, very large scale integration (vlsi) systems, ieee transactions on, ieee trans. vlsi syst.
(3)
international journal of speech-language pathology
(3)
journal of luminescence
(3)
ksce journal of civil engineering
(3)
metabolism: clinical and experimental
(3)
2022 7th international conference on intelligent computing and signal processing, icsp 2022
(2)
2023 8th international conference on power and renewable energy, icpre 2023
(2)
anz journal of surgery
(2)
atherosclerosis
(2)
biochimica et biophysica acta - biomembranes
(2)
cell adhesion and migration
(2)
ceramics international
(2)
food and function
(2)
global nest journal
(2)
hydraulic engineering iii - proceedings of the 3rd technical conference on hydraulic engineering, che 2014
(2)
journal of industrial microbiology and biotechnology
(2)
materials science and engineering c
(2)
materials science forum
(2)
military medicine
(2)
poultry science
(2)
proceedings - 2023 8th asia conference on power and electrical engineering, acpee 2023
(2)
proceedings of 2024 ieee 7th international electrical and energy conference, cieec 2024
(2)
rsc advances
(2)
textile research journal
(2)
tumu gongcheng xuebao/china civil engineering journal
(2)
zhongguo jixie gongcheng/china mechanical engineering
(2)
2007 9th european conference on radiation & its effects on components & systems
(1)
2009 joint urban remote sensing event
(1)
2009 wri world congress on computer science and information engineering, csie 2009
(1)
2011 ieee international conference on automatic face and gesture recognition and workshops, fg 2011
(1)
2014 6th international conference on communication systems and networks, comsnets 2014
(1)
2021 ieee international conference on artificial intelligence and computer applications, icaica 2021
(1)
2023 ieee 3rd international conference on electronic technology, communication and information, icetci 2023
(1)
atherosclerosis (00219150)
(1)
biomedical microdevices
(1)
glia
(1)
journal of peptide science
(1)
pediatric pulmonology
(1)
add
remove
더보기
zoom_in
재검색
출판사(Publisher)
ieee
(50)
institute of electrical and electronics engineers inc.
(24)
elsevier b.v.
(13)
elsevier ltd
(10)
elsevier science inc
(7)
royal society of chemistry
(7)
chinese medical journals publishing house co.ltd
(5)
american chemical society
(4)
elsevier inc.
(4)
john wiley and sons inc
(4)
biomed central ltd
(3)
institute of physics publishing
(3)
springer nature
(3)
springer verlag
(3)
w.b. saunders
(3)
biomed central ltd.
(2)
crc press/balkema
(2)
editorial office of china civil engineering journal
(2)
elsevier ireland ltd
(2)
ieee-inst electrical electronics engineers inc
(2)
john wiley and sons ltd
(2)
mdpi
(2)
mdpi ag
(2)
nature publishing group
(2)
oxford university press
(2)
sage publications ltd
(2)
taylor & francis ltd
(2)
taylor and francis inc.
(2)
taylor and francis ltd.
(2)
wiley-blackwell
(2)
academic press inc.
(1)
american academy of family physicians
(1)
american institute of aeronautics and astronautics inc.
(1)
american society of tropical medicine and hygiene
(1)
asian journal of pharmaceutical and clinical research
(1)
asme
(1)
association for computing machinery
(1)
association of military surgeons of the us
(1)
autom electr power syst press
(1)
blackwell munksgaard
(1)
blackwell publishing ltd
(1)
cailiao daobaoshe/ materials review
(1)
cambridge university press
(1)
china biotechnology press
(1)
china mechanical engineering magazine office
(1)
china translation and publishing corporation
(1)
chinese academy of fishery sciences
(1)
global network environmental science & technology
(1)
institute of electrical and electronics engineers, inc.
(1)
john wiley & sons ltd
(1)
add
remove
더보기
zoom_in
재검색
자료유형(Source Type)
Academic Journals
(232)
Conference Materials
(55)
Books
(6)
Reviews
(2)
Magazines
(2)
Reports
(1)
add
remove
더보기
zoom_in
재검색
주제어
components, circuits, devices and systems
(33)
computing and processing
(16)
engineered materials, dielectrics and plasmas
(13)
single event transient (set)
(12)
cmos
(10)
fields, waves and electromagnetics
(10)
bioengineering
(8)
let
(8)
temperature dependence
(8)
electrodes
(7)
phase locked loops
(7)
sensitivity
(7)
bandwidth
(6)
communication, networking and broadcast technologies
(6)
signal processing and analysis
(6)
technology computer-aided design (tcad) simulation
(6)
wireless communication
(6)
apoptosis
(5)
cambodia
(5)
clocks
(5)
delays
(5)
electrocardiography
(5)
heavy ion
(5)
phase noise
(5)
resistance
(5)
cell stress
(4)
chirp
(4)
dysphagia
(4)
frequency shift keying
(4)
integrated circuit modeling
(4)
magnetic tunneling
(4)
malaria
(4)
modulation
(4)
musca sep3
(4)
oscillators
(4)
sensors
(4)
single event upset (seu)
(4)
transistors
(4)
wireless sensor networks
(4)
capacitance
(3)
capacitors
(3)
cmos integrated circuits
(3)
complementary metal oxide semiconductors
(3)
computer architecture
(3)
data corruption
(3)
deglutition disorders
(3)
demodulation
(3)
electric inverters
(3)
energy transfer
(3)
feature extraction
(3)
add
remove
더보기
zoom_in
재검색
언어
english
(241)
chinese
(14)
french
(1)
add
remove
더보기
zoom_in
재검색
메일 발송
이메일
취소
확인
팝업 닫기
폴더 추가
팝업 닫기